Load :class:`mongomock.database.Database` from dict data.

def _load(db_data, db):
    """
    Load :class:`mongomock.database.Database` from dict data.
    """
    if db.name != db_data["name"]:
        raise ValueError("dbname doesn't matches! Maybe wrong database data.")

    db.__init__(client=db._client, name=db.name)
    for col_name, col_data in iteritems(db_data["_collections"]):
        collection = db.get_collection(col_name)
        collection._documents = col_data["_documents"]
        collection._uniques = col_data["_uniques"]
        db._collections[col_name] = collection

    return db