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class <tt class="descclassname">sqlalchemy.orm.instrumentation.</tt><tt class="descname">ClassManager</tt><big>(</big>class_<big>)</big><a class="headerlink" href="#sqlalchemy.orm.instrumentation.ClassManager" title="Permalink to this definition">¶</a></dt>

<dd>Bases: <tt class="xref py py-class docutils literal">dict</tt>

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tracks state information at the class level.

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<tt class="descname">dispose</tt><big>(</big><big>)</big><a class="headerlink" href="#sqlalchemy.orm.instrumentation.ClassManager.dispose" title="Permalink to this definition">¶</a></dt>

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<dd>Dissasociate this manager from its class.

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</dd></dl>

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<tt class="descname">has_parent</tt><big>(</big>state, key, optimistic=False<big>)</big><a class="headerlink" href="#sqlalchemy.orm.instrumentation.ClassManager.has_parent" title="Permalink to this definition">¶</a></dt>

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<dd>TODO

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</dd></dl>

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<tt class="descname">manage</tt><big>(</big><big>)</big><a class="headerlink" href="#sqlalchemy.orm.instrumentation.ClassManager.manage" title="Permalink to this definition">¶</a></dt>

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<dd>Mark this instance as the manager for its class.

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</dd></dl>

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<tt class="descname">original_init</tt><a class="headerlink" href="#sqlalchemy.orm.instrumentation.ClassManager.original_init" title="Permalink to this definition">¶</a></dt>

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<dd>x.__init__(...) initializes x; see help(type(x)) for signature

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</dd></dl>

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<tt class="descname">state_getter</tt><big>(</big><big>)</big><a class="headerlink" href="#sqlalchemy.orm.instrumentation.ClassManager.state_getter" title="Permalink to this definition">¶</a></dt>

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<dd>Return a (instance) -> InstanceState callable.

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“state getter” callables should raise either KeyError or

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AttributeError if no InstanceState could be found for the

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instance.

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</dd></dl>

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<tt class="descname">unregister</tt><big>(</big><big>)</big><a class="headerlink" href="#sqlalchemy.orm.instrumentation.ClassManager.unregister" title="Permalink to this definition">¶</a></dt>

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<dd>remove all instrumentation established by this ClassManager.

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</dd></dl>

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</dd></dl>

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class <tt class="descclassname">sqlalchemy.orm.properties.</tt><tt class="descname">ColumnProperty</tt><big>(</big>*columns, **kwargs<big>)</big><a class="headerlink" href="#sqlalchemy.orm.properties.ColumnProperty" title="Permalink to this definition">¶</a></dt>

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<dd>Bases: <tt class="xref py py-class docutils literal">sqlalchemy.orm.interfaces.StrategizedProperty</tt>

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Describes an object attribute that corresponds to a table column.

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Public constructor is the <a class="reference internal" href="mapper_config.html#sqlalchemy.orm.column_property" title="sqlalchemy.orm.column_property"><tt class="xref py py-func docutils literal">orm.column_property()</tt></a> function.

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<tt class="descname">__init__</tt><big>(</big>*columns, **kwargs<big>)</big><a class="headerlink" href="#sqlalchemy.orm.properties.ColumnProperty.__init__" title="Permalink to this definition">¶</a></dt>

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<dd>Construct a ColumnProperty.

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Note the public constructor is the <a class="reference internal" href="mapper_config.html#sqlalchemy.orm.column_property" title="sqlalchemy.orm.column_property"><tt class="xref py py-func docutils literal">orm.column_property()</tt></a> function.

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<tr class="field"><th class="field-name">Parameters:</th><td class="field-body"><ul class="first last simple">

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<li>*columns – The list of <cite>columns</cite> describes a single

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object property. If there are multiple tables joined

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together for the mapper, this list represents the equivalent

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column as it appears across each table.</li>

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<li>group – </li>

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<li>deferred – </li>

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<li>comparator_factory – </li>

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<li>descriptor – </li>

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<li>extension – </li>

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</ul>

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</td>

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</tr>

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</tbody>

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</table>

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</dd></dl>

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</dd></dl>

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class <tt class="descclassname">sqlalchemy.orm.descriptor_props.</tt><tt class="descname">CompositeProperty</tt><big>(</big>class_, *attrs, **kwargs<big>)</big><a class="headerlink" href="#sqlalchemy.orm.descriptor_props.CompositeProperty" title="Permalink to this definition">¶</a></dt>

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<dd>Bases: <tt class="xref py py-class docutils literal">sqlalchemy.orm.descriptor_props.DescriptorProperty</tt>

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<dd>Initialization which occurs after the <a class="reference internal" href="#sqlalchemy.orm.descriptor_props.CompositeProperty" title="sqlalchemy.orm.descriptor_props.CompositeProperty"><tt class="xref py py-class docutils literal">CompositeProperty</tt></a>

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has been associated with its parent mapper.

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</dd></dl>

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<tt class="descname">get_history</tt><big>(</big>state, dict_, passive=<symbol 'PASSIVE_OFF><big>)</big><a class="headerlink" href="#sqlalchemy.orm.descriptor_props.CompositeProperty.get_history" title="Permalink to this definition">¶</a></dt>

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<dd>Provided for userland code that uses attributes.get_history().

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</dd></dl>

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</dd></dl>

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class <tt class="descclassname">sqlalchemy.orm.state.</tt><tt class="descname">InstanceState</tt><big>(</big>obj, manager<big>)</big><a class="headerlink" href="#sqlalchemy.orm.state.InstanceState" title="Permalink to this definition">¶</a></dt>

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<dd>Bases: <tt class="xref py py-class docutils literal">object</tt>

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tracks state information at the instance level.

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<tt class="descname">commit</tt><big>(</big>dict_, keys<big>)</big><a class="headerlink" href="#sqlalchemy.orm.state.InstanceState.commit" title="Permalink to this definition">¶</a></dt>

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<dd>Commit attributes.

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This is used by a partial-attribute load operation to mark committed

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those attributes which were refreshed from the database.

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Attributes marked as “expired” can potentially remain “expired” after

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this step if a value was not populated in state.dict.

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</dd></dl>

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<tt class="descname">commit_all</tt><big>(</big>dict_, instance_dict=None<big>)</big><a class="headerlink" href="#sqlalchemy.orm.state.InstanceState.commit_all" title="Permalink to this definition">¶</a></dt>

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<dd>commit all attributes unconditionally.

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This is used after a flush() or a full load/refresh

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to remove all pending state from the instance.

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<li>all attributes are marked as “committed”</li>

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<li>the “strong dirty reference” is removed</li>

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<li>the “modified” flag is set to False</li>

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<li>any “expired” markers/callables for attributes loaded are removed.</li>

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</ul>

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</div></blockquote>

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Attributes marked as “expired” can potentially remain “expired” after this step

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if a value was not populated in state.dict.

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</dd></dl>

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<tt class="descname">expire_attribute_pre_commit</tt><big>(</big>dict_, key<big>)</big><a class="headerlink" href="#sqlalchemy.orm.state.InstanceState.expire_attribute_pre_commit" title="Permalink to this definition">¶</a></dt>

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<dd>a fast expire that can be called by column loaders during a load.

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The additional bookkeeping is finished up in commit_all().

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This method is actually called a lot with joined-table

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loading, when the second table isn’t present in the result.

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</dd></dl>

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<tt class="descname">expired_attributes</tt><a class="headerlink" href="#sqlalchemy.orm.state.InstanceState.expired_attributes" title="Permalink to this definition">¶</a></dt>

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<dd>Return the set of keys which are ‘expired’ to be loaded by

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the manager’s deferred scalar loader, assuming no pending

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changes.

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see also the <tt class="docutils literal">unmodified</tt> collection which is intersected

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against this set when a refresh operation occurs.

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</dd></dl>

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<tt class="descname">initialize</tt><big>(</big>key<big>)</big><a class="headerlink" href="#sqlalchemy.orm.state.InstanceState.initialize" title="Permalink to this definition">¶</a></dt>

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<dd>Set this attribute to an empty value or collection,

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based on the AttributeImpl in use.

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</dd></dl>

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<tt class="descname">reset</tt><big>(</big>dict_, key<big>)</big><a class="headerlink" href="#sqlalchemy.orm.state.InstanceState.reset" title="Permalink to this definition">¶</a></dt>

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<dd>Remove the given attribute and any

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callables associated with it.

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</dd></dl>

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<tt class="descname">set_callable</tt><big>(</big>dict_, key, callable_<big>)</big><a class="headerlink" href="#sqlalchemy.orm.state.InstanceState.set_callable" title="Permalink to this definition">¶</a></dt>

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<dd>Remove the given attribute and set the given callable

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as a loader.

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</dd></dl>

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<tt class="descname">unloaded</tt><a class="headerlink" href="#sqlalchemy.orm.state.InstanceState.unloaded" title="Permalink to this definition">¶</a></dt>

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<dd>Return the set of keys which do not have a loaded value.

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This includes expired attributes and any other attribute that

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was never populated or modified.

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</dd></dl>

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<tt class="descname">unmodified</tt><a class="headerlink" href="#sqlalchemy.orm.state.InstanceState.unmodified" title="Permalink to this definition">¶</a></dt>

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<dd>Return the set of keys which have no uncommitted changes

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</dd></dl>

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<tt class="descname">unmodified_intersection</tt><big>(</big>keys<big>)</big><a class="headerlink" href="#sqlalchemy.orm.state.InstanceState.unmodified_intersection" title="Permalink to this definition">¶</a></dt>

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<dd>Return self.unmodified.intersection(keys).

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</dd></dl>

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<tt class="descname">value_as_iterable</tt><big>(</big>dict_, key, passive=<symbol 'PASSIVE_OFF><big>)</big><a class="headerlink" href="#sqlalchemy.orm.state.InstanceState.value_as_iterable" title="Permalink to this definition">¶</a></dt>

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<dd>Return a list of tuples (state, obj) for the given

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key.

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returns an empty list if the value is None/empty/PASSIVE_NO_RESULT

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</dd></dl>

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</dd></dl>

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class <tt class="descclassname">sqlalchemy.orm.interfaces.</tt><tt class="descname">MapperProperty</tt><a class="headerlink" href="#sqlalchemy.orm.interfaces.MapperProperty" title="Permalink to this definition">¶</a></dt>

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<dd>Bases: <tt class="xref py py-class docutils literal">object</tt>

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Manage the relationship of a <tt class="docutils literal">Mapper</tt> to a single class

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attribute, as well as that attribute as it appears on individual

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instances of the class, including attribute instrumentation,

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attribute access, loading behavior, and dependency calculations.

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<tt class="descname">cascade</tt><a class="headerlink" href="#sqlalchemy.orm.interfaces.MapperProperty.cascade" title="Permalink to this definition">¶</a></dt>

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<dd>The set of ‘cascade’ attribute names.

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This collection is checked before the ‘cascade_iterator’ method is called.

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</dd></dl>

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<tt class="descname">cascade_iterator</tt><big>(</big>type_, state, visited_instances=None, halt_on=None<big>)</big><a class="headerlink" href="#sqlalchemy.orm.interfaces.MapperProperty.cascade_iterator" title="Permalink to this definition">¶</a></dt>

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<dd>Iterate through instances related to the given instance for

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a particular ‘cascade’, starting with this MapperProperty.

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Return an iterator3-tuples (instance, mapper, state).

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Note that the ‘cascade’ collection on this MapperProperty is

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checked first for the given type before cascade_iterator is called.

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See PropertyLoader for the related instance implementation.

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</dd></dl>

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<tt class="descname">class_attribute</tt><a class="headerlink" href="#sqlalchemy.orm.interfaces.MapperProperty.class_attribute" title="Permalink to this definition">¶</a></dt>

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<dd>Return the class-bound descriptor corresponding to this

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MapperProperty.

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</dd></dl>

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<tt class="descname">compare</tt><big>(</big>operator, value, **kw<big>)</big><a class="headerlink" href="#sqlalchemy.orm.interfaces.MapperProperty.compare" title="Permalink to this definition">¶</a></dt>

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<dd>Return a compare operation for the columns represented by

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this <tt class="docutils literal">MapperProperty</tt> to the given value, which may be a

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column value or an instance. ‘operator’ is an operator from

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the operators module, or from sql.Comparator.

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By default uses the PropComparator attached to this MapperProperty

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under the attribute name “comparator”.

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</dd></dl>

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<tt class="descname">create_row_processor</tt><big>(</big>context, path, reduced_path, mapper, row, adapter<big>)</big><a class="headerlink" href="#sqlalchemy.orm.interfaces.MapperProperty.create_row_processor" title="Permalink to this definition">¶</a></dt>

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<dd>Return a 3-tuple consisting of three row processing functions.

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</dd></dl>

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<dd>Perform subclass-specific initialization post-mapper-creation

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steps.

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This is a template method called by the <tt class="docutils literal">MapperProperty</tt>

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object’s init() method.

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</dd></dl>

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<dd>Called after all mappers are created to assemble

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relationships between mappers and perform other post-mapper-creation

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initialization steps.

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</dd></dl>

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<tt class="descname">is_primary</tt><big>(</big><big>)</big><a class="headerlink" href="#sqlalchemy.orm.interfaces.MapperProperty.is_primary" title="Permalink to this definition">¶</a></dt>

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<dd>Return True if this <tt class="docutils literal">MapperProperty</tt>‘s mapper is the

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primary mapper for its class.

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This flag is used to indicate that the <tt class="docutils literal">MapperProperty</tt> can

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define attribute instrumentation for the class at the class

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level (as opposed to the individual instance level).

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</dd></dl>

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<tt class="descname">merge</tt><big>(</big>session, source_state, source_dict, dest_state, dest_dict, load, _recursive<big>)</big><a class="headerlink" href="#sqlalchemy.orm.interfaces.MapperProperty.merge" title="Permalink to this definition">¶</a></dt>

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<dd>Merge the attribute represented by this <tt class="docutils literal">MapperProperty</tt>

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from source to destination object

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</dd></dl>

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<tt class="descname">post_instrument_class</tt><big>(</big>mapper<big>)</big><a class="headerlink" href="#sqlalchemy.orm.interfaces.MapperProperty.post_instrument_class" title="Permalink to this definition">¶</a></dt>

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<dd>Perform instrumentation adjustments that need to occur

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after init() has completed.

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</dd></dl>

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<tt class="descname">setup</tt><big>(</big>context, entity, path, reduced_path, adapter, **kwargs<big>)</big><a class="headerlink" href="#sqlalchemy.orm.interfaces.MapperProperty.setup" title="Permalink to this definition">¶</a></dt>

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<dd>Called by Query for the purposes of constructing a SQL statement.

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Each MapperProperty associated with the target mapper processes the

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statement referenced by the query context, adding columns and/or

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criterion as appropriate.

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</dd></dl>

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</dd></dl>

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class <tt class="descclassname">sqlalchemy.orm.interfaces.</tt><tt class="descname">PropComparator</tt><big>(</big>prop, mapper, adapter=None<big>)</big><a class="headerlink" href="#sqlalchemy.orm.interfaces.PropComparator" title="Permalink to this definition">¶</a></dt>

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<dd>Bases: <a class="reference internal" href="../core/expression_api.html#sqlalchemy.sql.operators.ColumnOperators" title="sqlalchemy.sql.operators.ColumnOperators"><tt class="xref py py-class docutils literal">sqlalchemy.sql.operators.ColumnOperators</tt></a>

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Defines comparison operations for MapperProperty objects.

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User-defined subclasses of <a class="reference internal" href="#sqlalchemy.orm.interfaces.PropComparator" title="sqlalchemy.orm.interfaces.PropComparator"><tt class="xref py py-class docutils literal">PropComparator</tt></a> may be created. The

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built-in Python comparison and math operator methods, such as

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<tt class="docutils literal">__eq__()</tt>, <tt class="docutils literal">__lt__()</tt>, <tt class="docutils literal">__add__()</tt>, can be overridden to provide

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new operator behavior. The custom <a class="reference internal" href="#sqlalchemy.orm.interfaces.PropComparator" title="sqlalchemy.orm.interfaces.PropComparator"><tt class="xref py py-class docutils literal">PropComparator</tt></a> is passed to

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the mapper property via the <tt class="docutils literal">comparator_factory</tt> argument. In each case,

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the appropriate subclass of <a class="reference internal" href="#sqlalchemy.orm.interfaces.PropComparator" title="sqlalchemy.orm.interfaces.PropComparator"><tt class="xref py py-class docutils literal">PropComparator</tt></a> should be used:

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<div class="highlight-python"><div class="highlight"><pre>from sqlalchemy.orm.properties import \

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ColumnProperty,\

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CompositeProperty,\

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RelationshipProperty

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class MyColumnComparator(ColumnProperty.Comparator):

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pass

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class MyCompositeComparator(CompositeProperty.Comparator):

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pass

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class MyRelationshipComparator(RelationshipProperty.Comparator):

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pass</pre></div>

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</div>

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<tt class="descname">adapted</tt><big>(</big>adapter<big>)</big><a class="headerlink" href="#sqlalchemy.orm.interfaces.PropComparator.adapted" title="Permalink to this definition">¶</a></dt>

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<dd>Return a copy of this PropComparator which will use the given

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adaption function on the local side of generated expressions.

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</dd></dl>

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<tt class="descname">any</tt><big>(</big>criterion=None, **kwargs<big>)</big><a class="headerlink" href="#sqlalchemy.orm.interfaces.PropComparator.any" title="Permalink to this definition">¶</a></dt>

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<dd>Return true if this collection contains any member that meets the

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given criterion.

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<dt>criterion</dt>

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<dd>an optional ClauseElement formulated against the member class’ table

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or attributes.</dd>

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<dt>**kwargs</dt>

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<dd>key/value pairs corresponding to member class attribute names which

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will be compared via equality to the corresponding values.</dd>

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</dl>

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</dd></dl>

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<tt class="descname">has</tt><big>(</big>criterion=None, **kwargs<big>)</big><a class="headerlink" href="#sqlalchemy.orm.interfaces.PropComparator.has" title="Permalink to this definition">¶</a></dt>

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<dd>Return true if this element references a member which meets the

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given criterion.

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<dt>criterion</dt>

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<dd>an optional ClauseElement formulated against the member class’ table

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or attributes.</dd>

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<dt>**kwargs</dt>

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<dd>key/value pairs corresponding to member class attribute names which

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will be compared via equality to the corresponding values.</dd>

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</dl>

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</dd></dl>

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<tt class="descname">of_type</tt><big>(</big>class_<big>)</big><a class="headerlink" href="#sqlalchemy.orm.interfaces.PropComparator.of_type" title="Permalink to this definition">¶</a></dt>

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<dd>Redefine this object in terms of a polymorphic subclass.

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Returns a new PropComparator from which further criterion can be

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evaluated.

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e.g.:

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<div class="highlight-python"><div class="highlight"><pre>query.join(Company.employees.of_type(Engineer)).\

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filter(Engineer.name=='foo')</pre></div>

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</div>

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<dt>class_</dt>

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<dd>a class or mapper indicating that criterion will be against

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this specific subclass.</dd>

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</dl>

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</dd></dl>

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</dd></dl>

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class <tt class="descclassname">sqlalchemy.orm.properties.</tt><tt class="descname">RelationshipProperty</tt><big>(</big>argument, secondary=None, primaryjoin=None, secondaryjoin=None, foreign_keys=None, uselist=None, order_by=False, backref=None, back_populates=None, post_update=False, cascade=False, extension=None, viewonly=False, lazy=True, collection_class=None, passive_deletes=False, passive_updates=True, remote_side=None, enable_typechecks=True, join_depth=None, comparator_factory=None, single_parent=False, innerjoin=False, doc=None, active_history=False, cascade_backrefs=True, load_on_pending=False, strategy_class=None, _local_remote_pairs=None, query_class=None<big>)</big><a class="headerlink" href="#sqlalchemy.orm.properties.RelationshipProperty" title="Permalink to this definition">¶</a></dt>

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<dd>Bases: <tt class="xref py py-class docutils literal">sqlalchemy.orm.interfaces.StrategizedProperty</tt>

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Describes an object property that holds a single item or list

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of items that correspond to a related database table.

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Public constructor is the <a class="reference internal" href="relationships.html#sqlalchemy.orm.relationship" title="sqlalchemy.orm.relationship"><tt class="xref py py-func docutils literal">orm.relationship()</tt></a> function.

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Of note here is the <a class="reference internal" href="#sqlalchemy.orm.properties.RelationshipProperty.Comparator" title="sqlalchemy.orm.properties.RelationshipProperty.Comparator"><tt class="xref py py-class docutils literal">RelationshipProperty.Comparator</tt></a>

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class, which implements comparison operations for scalar-

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and collection-referencing mapped attributes.

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class <tt class="descname">Comparator</tt><big>(</big>prop, mapper, of_type=None, adapter=None<big>)</big><a class="headerlink" href="#sqlalchemy.orm.properties.RelationshipProperty.Comparator" title="Permalink to this definition">¶</a></dt>

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<dd>Bases: <a class="reference internal" href="#sqlalchemy.orm.interfaces.PropComparator" title="sqlalchemy.orm.interfaces.PropComparator"><tt class="xref py py-class docutils literal">sqlalchemy.orm.interfaces.PropComparator</tt></a>

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Produce comparison operations for <a class="reference internal" href="relationships.html#sqlalchemy.orm.relationship" title="sqlalchemy.orm.relationship"><tt class="xref py py-func docutils literal">relationship()</tt></a>-based

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attributes.

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<tt class="descname">__eq__</tt><big>(</big>other<big>)</big><a class="headerlink" href="#sqlalchemy.orm.properties.RelationshipProperty.Comparator.__eq__" title="Permalink to this definition">¶</a></dt>

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<dd>Implement the <tt class="docutils literal">==</tt> operator.

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In a many-to-one context, such as:

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<div class="highlight-python"><pre>MyClass.some_prop == <some object></pre>

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</div>

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this will typically produce a

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clause such as:

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<div class="highlight-python"><pre>mytable.related_id == <some id></pre>

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</div>

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Where <tt class="docutils literal"><some id></tt> is the primary key of the given

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object.

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The <tt class="docutils literal">==</tt> operator provides partial functionality for non-

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many-to-one comparisons:

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<li>Comparisons against collections are not supported.

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Use <a class="reference internal" href="#sqlalchemy.orm.properties.RelationshipProperty.Comparator.contains" title="sqlalchemy.orm.properties.RelationshipProperty.Comparator.contains"><tt class="xref py py-meth docutils literal">contains()</tt></a>.</li>

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<li>Compared to a scalar one-to-many, will produce a

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clause that compares the target columns in the parent to

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the given target.</li>

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<li>Compared to a scalar many-to-many, an alias

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of the association table will be rendered as

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well, forming a natural join that is part of the

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main body of the query. This will not work for

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queries that go beyond simple AND conjunctions of

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comparisons, such as those which use OR. Use

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explicit joins, outerjoins, or

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<a class="reference internal" href="#sqlalchemy.orm.properties.RelationshipProperty.Comparator.has" title="sqlalchemy.orm.properties.RelationshipProperty.Comparator.has"><tt class="xref py py-meth docutils literal">has()</tt></a> for

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more comprehensive non-many-to-one scalar

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membership tests.</li>

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<li>Comparisons against <tt class="xref docutils literal">None</tt> given in a one-to-many

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or many-to-many context produce a NOT EXISTS clause.</li>

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</ul>

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</dd></dl>

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<tt class="descname">__init__</tt><big>(</big>prop, mapper, of_type=None, adapter=None<big>)</big><a class="headerlink" href="#sqlalchemy.orm.properties.RelationshipProperty.Comparator.__init__" title="Permalink to this definition">¶</a></dt>

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<dd>Construction of <a class="reference internal" href="#sqlalchemy.orm.properties.RelationshipProperty.Comparator" title="sqlalchemy.orm.properties.RelationshipProperty.Comparator"><tt class="xref py py-class docutils literal">RelationshipProperty.Comparator</tt></a>

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is internal to the ORM’s attribute mechanics.

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</dd></dl>

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<tt class="descname">__ne__</tt><big>(</big>other<big>)</big><a class="headerlink" href="#sqlalchemy.orm.properties.RelationshipProperty.Comparator.__ne__" title="Permalink to this definition">¶</a></dt>

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<dd>Implement the <tt class="docutils literal">!=</tt> operator.

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In a many-to-one context, such as:

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<div class="highlight-python"><pre>MyClass.some_prop != <some object></pre>

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</div>

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This will typically produce a clause such as:

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<div class="highlight-python"><pre>mytable.related_id != <some id></pre>

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</div>

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Where <tt class="docutils literal"><some id></tt> is the primary key of the

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given object.

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The <tt class="docutils literal">!=</tt> operator provides partial functionality for non-

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many-to-one comparisons:

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<li>Comparisons against collections are not supported.

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Use

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<a class="reference internal" href="#sqlalchemy.orm.properties.RelationshipProperty.Comparator.contains" title="sqlalchemy.orm.properties.RelationshipProperty.Comparator.contains"><tt class="xref py py-meth docutils literal">contains()</tt></a>

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in conjunction with <a class="reference internal" href="../core/expression_api.html#sqlalchemy.sql.expression.not_" title="sqlalchemy.sql.expression.not_"><tt class="xref py py-func docutils literal">not_()</tt></a>.</li>

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<li>Compared to a scalar one-to-many, will produce a

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clause that compares the target columns in the parent to

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the given target.</li>

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<li>Compared to a scalar many-to-many, an alias

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of the association table will be rendered as

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well, forming a natural join that is part of the

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main body of the query. This will not work for

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queries that go beyond simple AND conjunctions of

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comparisons, such as those which use OR. Use

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explicit joins, outerjoins, or

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conjunction with <a class="reference internal" href="../core/expression_api.html#sqlalchemy.sql.expression.not_" title="sqlalchemy.sql.expression.not_"><tt class="xref py py-func docutils literal">not_()</tt></a> for

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more comprehensive non-many-to-one scalar

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membership tests.</li>

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<li>Comparisons against <tt class="xref docutils literal">None</tt> given in a one-to-many

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or many-to-many context produce an EXISTS clause.</li>

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</ul>

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</dd></dl>

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<tt class="descname">adapted</tt><big>(</big>adapter<big>)</big><a class="headerlink" href="#sqlalchemy.orm.properties.RelationshipProperty.Comparator.adapted" title="Permalink to this definition">¶</a></dt>

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<dd>Return a copy of this PropComparator which will use the

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given adaption function on the local side of generated

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expressions.

584

</dd></dl>

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<tt class="descname">any</tt><big>(</big>criterion=None, **kwargs<big>)</big><a class="headerlink" href="#sqlalchemy.orm.properties.RelationshipProperty.Comparator.any" title="Permalink to this definition">¶</a></dt>

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<dd>Produce an expression that tests a collection against

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particular criterion, using EXISTS.

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An expression like:

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<div class="highlight-python"><div class="highlight"><pre>session.query(MyClass).filter(

593

MyClass.somereference.any(SomeRelated.x==2)

594

)</pre></div>

595

</div>

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Will produce a query like:

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<div class="highlight-python"><pre>SELECT * FROM my_table WHERE

598

EXISTS (SELECT 1 FROM related WHERE related.my_id=my_table.id

599

AND related.x=2)</pre>

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</div>

601

Because <a class="reference internal" href="#sqlalchemy.orm.properties.RelationshipProperty.Comparator.any" title="sqlalchemy.orm.properties.RelationshipProperty.Comparator.any"><tt class="xref py py-meth docutils literal">any()</tt></a> uses

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a correlated subquery, its performance is not nearly as

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good when compared against large target tables as that of

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using a join.

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<a class="reference internal" href="#sqlalchemy.orm.properties.RelationshipProperty.Comparator.any" title="sqlalchemy.orm.properties.RelationshipProperty.Comparator.any"><tt class="xref py py-meth docutils literal">any()</tt></a> is particularly

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useful for testing for empty collections:

607

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~MyClass.somereference.any()

609

)</pre></div>

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</div>

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will produce:

612

<div class="highlight-python"><pre>SELECT * FROM my_table WHERE

613

NOT EXISTS (SELECT 1 FROM related WHERE related.my_id=my_table.id)</pre>

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</div>

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valid for collections, i.e. a <a class="reference internal" href="relationships.html#sqlalchemy.orm.relationship" title="sqlalchemy.orm.relationship"><tt class="xref py py-func docutils literal">relationship()</tt></a>

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that has <tt class="docutils literal">uselist=True</tt>. For scalar references,

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use <a class="reference internal" href="#sqlalchemy.orm.properties.RelationshipProperty.Comparator.has" title="sqlalchemy.orm.properties.RelationshipProperty.Comparator.has"><tt class="xref py py-meth docutils literal">has()</tt></a>.

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</dd></dl>

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<tt class="descname">contains</tt><big>(</big>other, **kwargs<big>)</big><a class="headerlink" href="#sqlalchemy.orm.properties.RelationshipProperty.Comparator.contains" title="Permalink to this definition">¶</a></dt>

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<dd>Return a simple expression that tests a collection for

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containment of a particular item.

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<a class="reference internal" href="#sqlalchemy.orm.properties.RelationshipProperty.Comparator.contains" title="sqlalchemy.orm.properties.RelationshipProperty.Comparator.contains"><tt class="xref py py-meth docutils literal">contains()</tt></a> is

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only valid for a collection, i.e. a

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<a class="reference internal" href="relationships.html#sqlalchemy.orm.relationship" title="sqlalchemy.orm.relationship"><tt class="xref py py-func docutils literal">relationship()</tt></a> that implements

629

one-to-many or many-to-many with <tt class="docutils literal">uselist=True</tt>.

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When used in a simple one-to-many context, an

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expression like:

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<div class="highlight-python"><div class="highlight"><pre>MyClass.contains(other)</pre></div>

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</div>

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Produces a clause like:

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<div class="highlight-python"><pre>mytable.id == <some id></pre>

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</div>

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Where <tt class="docutils literal"><some id></tt> is the value of the foreign key

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attribute on <tt class="docutils literal">other</tt> which refers to the primary

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key of its parent object. From this it follows that

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very useful when used with simple one-to-many

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operations.

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For many-to-many operations, the behavior of

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has more caveats. The association table will be

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rendered in the statement, producing an “implicit”

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join, that is, includes multiple tables in the FROM

648

clause which are equated in the WHERE clause:

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<div class="highlight-python"><div class="highlight"><pre>query(MyClass).filter(MyClass.contains(other))</pre></div>

650

</div>

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Produces a query like:

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<div class="highlight-python"><pre>SELECT * FROM my_table, my_association_table AS

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my_association_table_1 WHERE

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my_table.id = my_association_table_1.parent_id

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AND my_association_table_1.child_id = <some id></pre>

656

</div>

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Where <tt class="docutils literal"><some id></tt> would be the primary key of

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<tt class="docutils literal">other</tt>. From the above, it is clear that

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will not work with many-to-many collections when

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used in queries that move beyond simple AND

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conjunctions, such as multiple

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expressions joined by OR. In such cases subqueries or

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explicit “outer joins” will need to be used instead.

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See <a class="reference internal" href="#sqlalchemy.orm.properties.RelationshipProperty.Comparator.any" title="sqlalchemy.orm.properties.RelationshipProperty.Comparator.any"><tt class="xref py py-meth docutils literal">any()</tt></a> for

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a less-performant alternative using EXISTS, or refer

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to <a class="reference internal" href="query.html#sqlalchemy.orm.query.Query.outerjoin" title="sqlalchemy.orm.query.Query.outerjoin"><tt class="xref py py-meth docutils literal">Query.outerjoin()</tt></a> as well as <a class="reference internal" href="tutorial.html#ormtutorial-joins">Querying with Joins</a>

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for more details on constructing outer joins.

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</dd></dl>

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<tt class="descname">has</tt><big>(</big>criterion=None, **kwargs<big>)</big><a class="headerlink" href="#sqlalchemy.orm.properties.RelationshipProperty.Comparator.has" title="Permalink to this definition">¶</a></dt>

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<dd>Produce an expression that tests a scalar reference against

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particular criterion, using EXISTS.

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An expression like:

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MyClass.somereference.has(SomeRelated.x==2)

680

)</pre></div>

681

</div>

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Will produce a query like:

683

<div class="highlight-python"><pre>SELECT * FROM my_table WHERE

684

EXISTS (SELECT 1 FROM related WHERE related.id==my_table.related_id

685

AND related.x=2)</pre>

686

</div>

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Because <a class="reference internal" href="#sqlalchemy.orm.properties.RelationshipProperty.Comparator.has" title="sqlalchemy.orm.properties.RelationshipProperty.Comparator.has"><tt class="xref py py-meth docutils literal">has()</tt></a> uses

688

a correlated subquery, its performance is not nearly as

689

good when compared against large target tables as that of

690

using a join.

691

<a class="reference internal" href="#sqlalchemy.orm.properties.RelationshipProperty.Comparator.has" title="sqlalchemy.orm.properties.RelationshipProperty.Comparator.has"><tt class="xref py py-meth docutils literal">has()</tt></a> is only

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valid for scalar references, i.e. a <a class="reference internal" href="relationships.html#sqlalchemy.orm.relationship" title="sqlalchemy.orm.relationship"><tt class="xref py py-func docutils literal">relationship()</tt></a>

693

that has <tt class="docutils literal">uselist=False</tt>. For collection references,

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use <a class="reference internal" href="#sqlalchemy.orm.properties.RelationshipProperty.Comparator.any" title="sqlalchemy.orm.properties.RelationshipProperty.Comparator.any"><tt class="xref py py-meth docutils literal">any()</tt></a>.

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</dd></dl>

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<tt class="descname">in_</tt><big>(</big>other<big>)</big><a class="headerlink" href="#sqlalchemy.orm.properties.RelationshipProperty.Comparator.in_" title="Permalink to this definition">¶</a></dt>

700

<dd>Produce an IN clause - this is not implemented

701

for <a class="reference internal" href="relationships.html#sqlalchemy.orm.relationship" title="sqlalchemy.orm.relationship"><tt class="xref py py-func docutils literal">relationship()</tt></a>-based attributes at this time.

702

</dd></dl>

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<dd>Produce a construct that represents a particular ‘subtype’ of

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attribute for the parent class.

709

Currently this is usable in conjunction with <a class="reference internal" href="query.html#sqlalchemy.orm.query.Query.join" title="sqlalchemy.orm.query.Query.join"><tt class="xref py py-meth docutils literal">Query.join()</tt></a>

710

and <a class="reference internal" href="query.html#sqlalchemy.orm.query.Query.outerjoin" title="sqlalchemy.orm.query.Query.outerjoin"><tt class="xref py py-meth docutils literal">Query.outerjoin()</tt></a>.

711

</dd></dl>

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</dd></dl>

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<tt class="descclassname">RelationshipProperty.</tt><tt class="descname">mapper</tt><a class="headerlink" href="#sqlalchemy.orm.properties.RelationshipProperty.mapper" title="Permalink to this definition">¶</a></dt>

718

<dd>Return the targeted <a class="reference internal" href="mapper_config.html#sqlalchemy.orm.mapper.Mapper" title="sqlalchemy.orm.mapper.Mapper"><tt class="xref py py-class docutils literal">Mapper</tt></a> for this

719

<a class="reference internal" href="#sqlalchemy.orm.properties.RelationshipProperty" title="sqlalchemy.orm.properties.RelationshipProperty"><tt class="xref py py-class docutils literal">RelationshipProperty</tt></a>.

720

This is a lazy-initializing static attribute.

721

</dd></dl>

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<tt class="descclassname">RelationshipProperty.</tt><tt class="descname">table</tt><a class="headerlink" href="#sqlalchemy.orm.properties.RelationshipProperty.table" title="Permalink to this definition">¶</a></dt>

726

<dd>Return the selectable linked to this

727

728

Deprecated since version 0.7: Use .target

729

<a class="reference internal" href="#sqlalchemy.orm.properties.RelationshipProperty" title="sqlalchemy.orm.properties.RelationshipProperty"><tt class="xref py py-class docutils literal">RelationshipProperty</tt></a> object’s target

730

<a class="reference internal" href="mapper_config.html#sqlalchemy.orm.mapper.Mapper" title="sqlalchemy.orm.mapper.Mapper"><tt class="xref py py-class docutils literal">Mapper</tt></a>.

731

</dd></dl>

732

733

</dd></dl>

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class <tt class="descclassname">sqlalchemy.orm.descriptor_props.</tt><tt class="descname">SynonymProperty</tt><big>(</big>name, map_column=None, descriptor=None, comparator_factory=None, doc=None<big>)</big><a class="headerlink" href="#sqlalchemy.orm.descriptor_props.SynonymProperty" title="Permalink to this definition">¶</a></dt>

738

<dd>Bases: <tt class="xref py py-class docutils literal">sqlalchemy.orm.descriptor_props.DescriptorProperty</tt>

739

</dd></dl>

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class <tt class="descclassname">sqlalchemy.orm.query.</tt><tt class="descname">QueryContext</tt><big>(</big>query<big>)</big><a class="headerlink" href="#sqlalchemy.orm.query.QueryContext" title="Permalink to this definition">¶</a></dt>

744

<dd>Bases: <tt class="xref py py-class docutils literal">object</tt>

745

</dd></dl>

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</div>

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</div>

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</div>

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<a href="exceptions.html" title="previous chapter">ORM Exceptions</a>

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<a href="../core/index.html" title="next chapter">SQLAlchemy Core</a>

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