path: root/mediagoblin/db/sql/util.py

# GNU MediaGoblin -- federated, autonomous media hosting
# Copyright (C) 2011, 2012 MediaGoblin contributors.  See AUTHORS.
#
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU Affero General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU Affero General Public License for more details.
#
# You should have received a copy of the GNU Affero General Public License
# along with this program.  If not, see <http://www.gnu.org/licenses/>.


import sys
from mediagoblin.db.sql.base import Session
from mediagoblin.db.sql.models import MediaEntry, Tag, MediaTag, Collection

from mediagoblin.tools.common import simple_printer


class MigrationManager(object):
    """
    Migration handling tool.

    Takes information about a database, lets you update the database
    to the latest migrations, etc.
    """

    def __init__(self, name, models, migration_registry, session,
                 printer=simple_printer):
        """
        Args:
         - name: identifier of this section of the database
         - session: session we're going to migrate
         - migration_registry: where we should find all migrations to
           run
        """
        self.name = unicode(name)
        self.models = models
        self.session = session
        self.migration_registry = migration_registry
        self._sorted_migrations = None
        self.printer = printer

        # For convenience
        from mediagoblin.db.sql.models import MigrationData

        self.migration_model = MigrationData
        self.migration_table = MigrationData.__table__

    @property
    def sorted_migrations(self):
        """
        Sort migrations if necessary and store in self._sorted_migrations
        """
        if not self._sorted_migrations:
            self._sorted_migrations = sorted(
                self.migration_registry.items(),
                # sort on the key... the migration number
                key=lambda migration_tuple: migration_tuple[0])

        return self._sorted_migrations

    @property
    def migration_data(self):
        """
        Get the migration row associated with this object, if any.
        """
        return self.session.query(
            self.migration_model).filter_by(name=self.name).first()

    @property
    def latest_migration(self):
        """
        Return a migration number for the latest migration, or 0 if
        there are no migrations.
        """
        if self.sorted_migrations:
            return self.sorted_migrations[-1][0]
        else:
            # If no migrations have been set, we start at 0.
            return 0

    @property
    def database_current_migration(self):
        """
        Return the current migration in the database.
        """
        # If the table doesn't even exist, return None.
        if not self.migration_table.exists(self.session.bind):
            return None

        # Also return None if self.migration_data is None.
        if self.migration_data is None:
            return None

        return self.migration_data.version

    def set_current_migration(self, migration_number=None):
        """
        Set the migration in the database to migration_number
        (or, the latest available)
        """
        self.migration_data.version = migration_number or self.latest_migration
        self.session.commit()

    def migrations_to_run(self):
        """
        Get a list of migrations to run still, if any.
        
        Note that this will fail if there's no migration record for
        this class!
        """
        assert self.database_current_migration is not None

        db_current_migration = self.database_current_migration
        
        return [
            (migration_number, migration_func)
            for migration_number, migration_func in self.sorted_migrations
            if migration_number > db_current_migration]


    def init_tables(self):
        """
        Create all tables relative to this package
        """
        # sanity check before we proceed, none of these should be created
        for model in self.models:
            # Maybe in the future just print out a "Yikes!" or something?
            assert not model.__table__.exists(self.session.bind)

        self.migration_model.metadata.create_all(
            self.session.bind,
            tables=[model.__table__ for model in self.models])

    def create_new_migration_record(self):
        """
        Create a new migration record for this migration set
        """
        migration_record = self.migration_model(
            name=self.name,
            version=self.latest_migration)
        self.session.add(migration_record)
        self.session.commit()

    def dry_run(self):
        """
        Print out a dry run of what we would have upgraded.
        """
        if self.database_current_migration is None:
            self.printer(
                    u'~> Woulda initialized: %s\n' % self.name_for_printing())
            return u'inited'

        migrations_to_run = self.migrations_to_run()
        if migrations_to_run:
            self.printer(
                u'~> Woulda updated %s:\n' % self.name_for_printing())

            for migration_number, migration_func in migrations_to_run():
                self.printer(
                    u'   + Would update %s, "%s"\n' % (
                        migration_number, migration_func.func_name))

            return u'migrated'
        
    def name_for_printing(self):
        if self.name == u'__main__':
            return u"main mediagoblin tables"
        else:
            # TODO: Use the friendlier media manager "human readable" name
            return u'media type "%s"' % self.name

    def init_or_migrate(self):
        """
        Initialize the database or migrate if appropriate.

        Returns information about whether or not we initialized
        ('inited'), migrated ('migrated'), or did nothing (None)
        """
        assure_migrations_table_setup(self.session)

        # Find out what migration number, if any, this database data is at,
        # and what the latest is.
        migration_number = self.database_current_migration

        # Is this our first time?  Is there even a table entry for
        # this identifier?
        # If so:
        #  - create all tables
        #  - create record in migrations registry
        #  - print / inform the user
        #  - return 'inited'
        if migration_number is None:
            self.printer(u"-> Initializing %s... " % self.name_for_printing())

            self.init_tables()
            # auto-set at latest migration number
            self.create_new_migration_record()  
            
            self.printer(u"done.\n")
            self.set_current_migration()
            return u'inited'

        # Run migrations, if appropriate.
        migrations_to_run = self.migrations_to_run()
        if migrations_to_run:
            self.printer(
                u'-> Updating %s:\n' % self.name_for_printing())
            for migration_number, migration_func in migrations_to_run:
                self.printer(
                    u'   + Running migration %s, "%s"... ' % (
                        migration_number, migration_func.func_name))
                migration_func(self.session)
                self.printer('done.\n')

            self.set_current_migration()
            return u'migrated'

        # Otherwise return None.  Well it would do this anyway, but
        # for clarity... ;)
        return None


class RegisterMigration(object):
    """
    Tool for registering migrations

    Call like:

    @RegisterMigration(33)
    def update_dwarves(database):
        [...]

    This will register your migration with the default migration
    registry.  Alternately, to specify a very specific
    migration_registry, you can pass in that as the second argument.

    Note, the number of your migration should NEVER be 0 or less than
    0.  0 is the default "no migrations" state!
    """
    def __init__(self, migration_number, migration_registry):
        assert migration_number > 0, "Migration number must be > 0!"
        assert migration_number not in migration_registry, \
            "Duplicate migration numbers detected!  That's not allowed!"

        self.migration_number = migration_number
        self.migration_registry = migration_registry

    def __call__(self, migration):
        self.migration_registry[self.migration_number] = migration
        return migration


def assure_migrations_table_setup(db):
    """
    Make sure the migrations table is set up in the database.
    """
    from mediagoblin.db.sql.models import MigrationData

    if not MigrationData.__table__.exists(db.bind):
        MigrationData.metadata.create_all(
            db.bind, tables=[MigrationData.__table__])


##########################
# Random utility functions
##########################


def atomic_update(table, query_dict, update_values):
    table.find(query_dict).update(update_values,
    	synchronize_session=False)
    Session.commit()


def check_media_slug_used(dummy_db, uploader_id, slug, ignore_m_id):
    filt = (MediaEntry.uploader == uploader_id) \
        & (MediaEntry.slug == slug)
    if ignore_m_id is not None:
        filt = filt & (MediaEntry.id != ignore_m_id)
    does_exist = Session.query(MediaEntry.id).filter(filt).first() is not None
    return does_exist


def media_entries_for_tag_slug(dummy_db, tag_slug):
    return MediaEntry.query \
        .join(MediaEntry.tags_helper) \
        .join(MediaTag.tag_helper) \
        .filter(
            (MediaEntry.state == u'processed')
            & (Tag.slug == tag_slug))


def clean_orphan_tags():
    q1 = Session.query(Tag).outerjoin(MediaTag).filter(MediaTag.id==None)
    for t in q1:
        Session.delete(t)

    # The "let the db do all the work" version:
    # q1 = Session.query(Tag.id).outerjoin(MediaTag).filter(MediaTag.id==None)
    # q2 = Session.query(Tag).filter(Tag.id.in_(q1))
    # q2.delete(synchronize_session = False)

    Session.commit()


def check_collection_slug_used(dummy_db, creator_id, slug, ignore_c_id):
    filt = (Collection.creator == creator_id) \
        & (Collection.slug == slug)
    if ignore_c_id is not None:
        filt = filt & (Collection.id != ignore_c_id)
    does_exist = Session.query(Collection.id).filter(filt).first() is not None
    return does_exist


if __name__ == '__main__':
    from mediagoblin.db.sql.open import setup_connection_and_db_from_config

    conn,db = setup_connection_and_db_from_config({'sql_engine':'sqlite:///mediagoblin.db'})

    clean_orphan_tags()