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author | Damian Dimmich <damian@tauri-tec.com> | 2014-06-24 11:23:21 +0400 |
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committer | Damian Dimmich <damian@tauri-tec.com> | 2014-06-24 11:23:21 +0400 |
commit | 01cc8fbacce8f571a47a3617b913e579bd666f97 (patch) | |
tree | 25428147b849bc3498be322619d819687ee813e6 /lib/sqlalchemy/dialects/postgresql/json.py | |
parent | f10eb28d90cbf73f4757897f52bf26722f98372e (diff) | |
download | sqlalchemy-01cc8fbacce8f571a47a3617b913e579bd666f97.tar.gz |
initial support for JSONB - this only allows you to define the JSONB
datatype - this does not add any of the additional support for
querying/indexing yet.
Diffstat (limited to 'lib/sqlalchemy/dialects/postgresql/json.py')
-rw-r--r-- | lib/sqlalchemy/dialects/postgresql/json.py | 113 |
1 files changed, 112 insertions, 1 deletions
diff --git a/lib/sqlalchemy/dialects/postgresql/json.py b/lib/sqlalchemy/dialects/postgresql/json.py index 2e29185e8..37196dfb1 100644 --- a/lib/sqlalchemy/dialects/postgresql/json.py +++ b/lib/sqlalchemy/dialects/postgresql/json.py @@ -14,7 +14,7 @@ from ... import sql from ...sql import elements from ... import util -__all__ = ('JSON', 'JSONElement') +__all__ = ('JSON', 'JSONElement', 'JSONB') class JSONElement(elements.BinaryExpression): @@ -197,3 +197,114 @@ class JSON(sqltypes.TypeEngine): ischema_names['json'] = JSON + + + +class JSONB(sqltypes.TypeEngine): + """Represent the Postgresql JSONB type. + + The :class:`.JSONB` type stores arbitrary JSONB format data, e.g.:: + + data_table = Table('data_table', metadata, + Column('id', Integer, primary_key=True), + Column('data', JSONB) + ) + + with engine.connect() as conn: + conn.execute( + data_table.insert(), + data = {"key1": "value1", "key2": "value2"} + ) + + :class:`.JSONB` provides several operations: + + * Index operations:: + + data_table.c.data['some key'] + + * Index operations returning text (required for text comparison):: + + data_table.c.data['some key'].astext == 'some value' + + * Index operations with a built-in CAST call:: + + data_table.c.data['some key'].cast(Integer) == 5 + + * Path index operations:: + + data_table.c.data[('key_1', 'key_2', ..., 'key_n')] + + * Path index operations returning text (required for text comparison):: + + data_table.c.data[('key_1', 'key_2', ..., 'key_n')].astext == 'some value' + + Index operations return an instance of :class:`.JSONElement`, which represents + an expression such as ``column -> index``. This element then defines + methods such as :attr:`.JSONElement.astext` and :meth:`.JSONElement.cast` + for setting up type behavior. + + The :class:`.JSON` type, when used with the SQLAlchemy ORM, does not detect + in-place mutations to the structure. In order to detect these, the + :mod:`sqlalchemy.ext.mutable` extension must be used. This extension will + allow "in-place" changes to the datastructure to produce events which + will be detected by the unit of work. See the example at :class:`.HSTORE` + for a simple example involving a dictionary. + + Custom serializers and deserializers are specified at the dialect level, + that is using :func:`.create_engine`. The reason for this is that when + using psycopg2, the DBAPI only allows serializers at the per-cursor + or per-connection level. E.g.:: + + engine = create_engine("postgresql://scott:tiger@localhost/test", + json_serializer=my_serialize_fn, + json_deserializer=my_deserialize_fn + ) + + When using the psycopg2 dialect, the json_deserializer is registered + against the database using ``psycopg2.extras.register_default_json``. + + .. versionadded:: 0.9.7 + + """ + + __visit_name__ = 'JSONB' + + class comparator_factory(sqltypes.Concatenable.Comparator): + """Define comparison operations for :class:`.JSON`.""" + + def __getitem__(self, other): + """Get the value at a given key.""" + + return JSONElement(self.expr, other) + + def _adapt_expression(self, op, other_comparator): + if isinstance(op, custom_op): + if op.opstring == '->': + return op, sqltypes.Text + return sqltypes.Concatenable.Comparator.\ + _adapt_expression(self, op, other_comparator) + + def bind_processor(self, dialect): + json_serializer = dialect._json_serializer or json.dumps + if util.py2k: + encoding = dialect.encoding + def process(value): + return json_serializer(value).encode(encoding) + else: + def process(value): + return json_serializer(value) + return process + + def result_processor(self, dialect, coltype): + json_deserializer = dialect._json_deserializer or json.loads + if util.py2k: + encoding = dialect.encoding + def process(value): + return json_deserializer(value.decode(encoding)) + else: + def process(value): + return json_deserializer(value) + return process + + +ischema_names['jsonb'] = JSONB
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