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  • Committer: Gustavo Niemeyer
  • Date: 2007-08-07 23:15:09 UTC
  • mfrom: (156.1.8 preset-primary-key)
  • Revision ID: gustavo@niemeyer.net-20070807231509-iw58uiygzuef5wth
Merged preset-primary-key branch [r=radix,jkakar] [f=126080]

This branch introduces a new hook which allows backends to modify
variables which are part of the primary key of an object before
they are inserted in the database.  Also, lazy values may now be
used in the primary key, which means that it's possible to set these
primary variables to SQL expressions if needed.

Other minor changes include an optimization in Result: it will
preset the raw cursor's arraysize to a better value if it's found
to be 1.  Result.__iter__() was also fixed to parse rows through
the from_database hook.

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Lines of Context:
storm/store.py
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            del obj_info["store"]
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        elif pending is PENDING_ADD:
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            columns = []
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            variables = []
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            for column in cls_info.columns:
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                variable = obj_info.variables[column]
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                if variable.is_defined():
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                    columns.append(column)
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                    variables.append(variable)
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                else:
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                    lazy_value = variable.get_lazy()
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                    if isinstance(lazy_value, Expr):
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                        columns.append(column)
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                        variables.append(lazy_value)
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            expr = Insert(columns, variables, cls_info.table)
 
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            # Give a chance to the backend to process primary variables.
 
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            self._connection.preset_primary_key(cls_info.primary_key,
 
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                                                obj_info.primary_vars)
 
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            changes = self._get_changes_map(obj_info, True)
 
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            expr = Insert(changes, cls_info.table,
 
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                          primary_columns=cls_info.primary_key,
 
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                          primary_variables=obj_info.primary_vars)
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            result = self._connection.execute(expr)
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            cached_primary_vars = obj_info["primary_vars"]
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            primary_key_idx = cls_info.primary_key_idx
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            changes = {}
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            for column in cls_info.columns:
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                variable = obj_info.variables[column]
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                if variable.has_changed():
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                    if variable.is_defined():
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                        changes[column] = variable
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                    else:
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                        lazy_value = variable.get_lazy()
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                        if isinstance(lazy_value, Expr):
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                            changes[column] = lazy_value
 
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            changes = self._get_changes_map(obj_info)
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            if changes:
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                expr = Update(changes,
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        obj_info.event.emit("flushed")
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    def _get_changes_map(self, obj_info, adding=False):
 
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        """Return a {column: variable} dictionary suitable for inserts/updates.
 
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        @param obj_info: ObjectInfo to inspect for changes.
 
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        @param adding: If true, any defined variables will be considered
 
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                       a change and included in the returned map.
 
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        """
 
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        cls_info = obj_info.cls_info
 
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        changes = {}
 
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        select_variables = []
 
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        for column in cls_info.columns:
 
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            variable = obj_info.variables[column]
 
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            if adding or variable.has_changed():
 
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                if variable.is_defined():
 
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                    changes[column] = variable
 
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                else:
 
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                    lazy_value = variable.get_lazy()
 
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                    if isinstance(lazy_value, Expr):
 
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                        if id(column) in cls_info.primary_key_idx:
 
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                            select_variables.append(variable) # See below.
 
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                            changes[column] = variable
 
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                        else:
 
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                            changes[column] = lazy_value
 
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        # If we have any expressions in the primary variables, we
 
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        # have to resolve them now so that we have the identity of
 
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        # the inserted object available later.
 
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        if select_variables:
 
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            resolve_expr = Select([variable.get_lazy()
 
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                                   for variable in select_variables])
 
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            result = self._connection.execute(resolve_expr)
 
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            for variable, value in zip(select_variables, result.get_one()):
 
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                result.set_variable(variable, value)
 
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        return changes
 
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    def _fill_missing_values(self, obj_info, primary_vars, result=None,
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                             checkpoint=True, replace_lazy=False):
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        """Query retrieve from the database any missing values in obj_info.