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  • Committer: Rick Harding
  • Date: 2013-01-10 17:33:50 UTC
  • mto: This revision was merged to the branch mainline in revision 102.
  • Revision ID: rick.harding@canonical.com-20130110173350-fz1z91843morskow
Initial migrations code with a couple passing tests

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migrations/migrate.py
 
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"""Migrate data for the mongodb instance.
 
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Loads migrations from the latest available in the versions directory.
 
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"""
 
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import os
 
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import re
 
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class DataStore(object):
 
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    """Communicate with the data store to determine version status."""
 
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    def __init__(self, db):
 
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        """Talk to the data store
 
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        :param db: The mongo db connection.
 
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        """
 
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        self.db = db
 
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    def current_version(self):
 
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        """Return the current version of the data store."""
 
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        return self.db.version.find_one({
 
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            '_id': 'version'
 
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        })
 
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    def version_datastore(self):
 
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        """Init the data to track the current version in the datastore.
 
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        The data store starts out with version 0.
 
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        Raises exception if the store is already versioned.
 
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        """
 
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        if self.current_version:
 
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            raise('Data store is already versioned: ' + self.current_version)
 
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        self.db.version.insert({'_id': 'version', 'version': 0})
 
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class Versions(object):
 
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    FILENAME_WITH_VERSION = re.compile(r'^(\d{3,}).*')
 
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    def _next_ver_num(self, use_timestamp_numbering):
 
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        return self.latest + 1
 
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    def _version_path(self, ver):
 
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        """Returns path of file in versions repository"""
 
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        return os.path.join(self.path, str(ver))
 
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    def __init__(self, path):
 
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        """Collect version scripts and store them in self.versions
 
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        """
 
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        # Create temporary list of files, allowing skipped version numbers.
 
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        files = os.listdir(path)
 
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        versions = {}
 
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        for name in files:
 
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            match = self.FILENAME_WITH_VERSION.match(name)
 
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            if match:
 
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                num = int(match.group(1))
 
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                versions[num] = name
 
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            else:
 
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                pass  # Must be a helper file or something, let's ignore it.
 
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        self.versions = {}
 
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        version_numbers = versions.keys()
 
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        version_numbers.sort()
 
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        self.version_indexes = version_numbers
 
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        for idx in version_numbers:
 
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            self.versions[idx] = versions[idx]
 
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    def create_new_python_version(self, description, **k):
 
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        """Create Python files for new version"""
 
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        ver = self._next_ver_num(k.pop('use_timestamp_numbering', False))
 
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        extra = str_to_filename(description)
 
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        if extra:
 
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            if extra == '_':
 
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                extra = ''
 
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            elif not extra.startswith('_'):
 
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                extra = '_%s' % extra
 
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        filename = '%03d%s.py' % (ver, extra)
 
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        filepath = self._version_path(filename)
 
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        script.PythonScript.create(filepath, **k)
 
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        self.versions[ver] = Version(ver, self.path, [filename])
 
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    @property
 
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    def latest(self):
 
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        """:returns: Latest version in Collection"""
 
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        return self.version_indexes[-1]