Python DBSession.begin_nested方法代码示例

# 需要导入模块: from mediacore.model.meta import DBSession [as 别名]
# 或者: from mediacore.model.meta.DBSession import begin_nested [as 别名]
    def increment_views(self):
        """Increment the number of views in the database.

        We avoid concurrency issues by incrementing JUST the views and
        not allowing modified_on to be updated automatically.

        """
        if self.id is None:
            self.views += 1
            return self.views

        # Don't raise an exception should concurrency problems occur.
        # Views will not actually be incremented in this case, but thats
        # relatively unimportant compared to rendering the page for the user.
        # We may be able to remove this after we improve our triggers to not
        # issue an UPDATE on media_fulltext unless one of its columns are
        # actually changed. Even when just media.views is updated, all the
        # columns in the corresponding media_fulltext row are updated, and
        # media_fulltext's MyISAM engine must lock the whole table to do so.
        transaction = DBSession.begin_nested()
        try:
            DBSession.query(self.__class__)\
                .filter(self.__class__.id == self.id)\
                .update({self.__class__.views: self.__class__.views + 1})
            transaction.commit()
        except exc.OperationalError, e:
            transaction.rollback()
            # (OperationalError) (1205, 'Lock wait timeout exceeded, try restarting the transaction')
            if not '1205' in e.message:
                raise

# 需要导入模块: from mediacore.model.meta import DBSession [as 别名]
# 或者: from mediacore.model.meta.DBSession import begin_nested [as 别名]
def insert_settings(defaults):
    """Insert the given setting if they don't exist yet.

    XXX: Does not include any support for MultiSetting. This approach
         won't work for that. We'll need to use sqlalchemy-migrate.

    :type defaults: list
    :param defaults: Key and value pairs
    :rtype: list
    :returns: Any settings that have just been created.
    """
    inserted = []
    existing_settings = set(x[0] for x in DBSession.query(Setting.key) \
                                     .filter(Setting.key \
                                     .in_(key for key, value in defaults)))

    for key, value in defaults:
        if key in existing_settings:
            continue
        transaction = DBSession.begin_nested()
        try:
            s = Setting(key, value)
            DBSession.add(s)
            transaction.commit()
            inserted.append(s)
        except IntegrityError:
            transaction.rollback()
    if inserted:
        DBSession.commit()
    return inserted

# 需要导入模块: from mediacore.model.meta import DBSession [as 别名]
# 或者: from mediacore.model.meta.DBSession import begin_nested [as 别名]
def insert_settings(defaults):
    """Insert the given setting if they don't exist yet.

    XXX: Does not include any support for MultiSetting. This approach
         won't work for that. We'll need to use sqlalchemy-migrate.

    :type defaults: list
    :param defaults: Key and value pairs
    :rtype: list
    :returns: Any settings that have just been created.
    """
    inserted = []
    try:
        settings_query = DBSession.query(Setting.key)\
            .filter(Setting.key.in_([key for key, value in defaults]))
        existing_settings = set(x[0] for x in settings_query)
    except ProgrammingError:
        # If we are running paster setup-app on a fresh database with a
        # plugin which tries to use this function every time the
        # Environment.loaded event fires, the settings table will not
        # exist and this exception will be thrown, but its safe to ignore.
        # The settings will be created the next time the event fires,
        # which will likely be the first time the app server starts up.
        return inserted
    for key, value in defaults:
        if key in existing_settings:
            continue
        transaction = DBSession.begin_nested()
        try:
            s = Setting(key, value)
            DBSession.add(s)
            transaction.commit()
            inserted.append(s)
        except IntegrityError:
            transaction.rollback()
    if inserted:
        DBSession.commit()
    return inserted