sqlalchemy.dialects.postgresql.json.JSON

class documentation

class JSON(sqltypes.JSON): (source)

Known subclasses: sqlalchemy.dialects.postgresql.asyncpg.AsyncpgJSON, sqlalchemy.dialects.postgresql.json.JSONB, sqlalchemy.dialects.postgresql.pg8000._PGJSON, sqlalchemy.dialects.postgresql.psycopg._PGJSON, sqlalchemy.dialects.postgresql.psycopg2._PGJSON

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Represent the PostgreSQL JSON type. :class:`_postgresql.JSON` is used automatically whenever the base :class:`_types.JSON` datatype is used against a PostgreSQL backend, however base :class:`_types.JSON` datatype does not provide Python accessors for PostgreSQL-specific comparison methods such as :meth:`_postgresql.JSON.Comparator.astext`; additionally, to use PostgreSQL ``JSONB``, the :class:`_postgresql.JSONB` datatype should be used explicitly. .. seealso:: :class:`_types.JSON` - main documentation for the generic cross-platform JSON datatype. The operators provided by the PostgreSQL version of :class:`_types.JSON` include: * Index operations (the ``->`` operator):: data_table.c.data['some key'] data_table.c.data[5] * Index operations returning text (the ``->>`` operator):: data_table.c.data['some key'].astext == 'some value' Note that equivalent functionality is available via the :attr:`.JSON.Comparator.as_string` accessor. * Index operations with CAST (equivalent to ``CAST(col ->> ['some key'] AS <type>)``):: data_table.c.data['some key'].astext.cast(Integer) == 5 Note that equivalent functionality is available via the :attr:`.JSON.Comparator.as_integer` and similar accessors. * Path index operations (the ``#>`` operator):: data_table.c.data[('key_1', 'key_2', 5, ..., 'key_n')] * Path index operations returning text (the ``#>>`` operator):: data_table.c.data[('key_1', 'key_2', 5, ..., 'key_n')].astext == 'some value' .. versionchanged:: 1.1 The :meth:`_expression.ColumnElement.cast` operator on JSON objects now requires that the :attr:`.JSON.Comparator.astext` modifier be called explicitly, if the cast works only from a textual string. Index operations return an expression object whose type defaults to :class:`_types.JSON` by default, so that further JSON-oriented instructions may be called upon the result type. Custom serializers and deserializers are specified at the dialect level, that is using :func:`_sa.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+psycopg2://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``. .. seealso:: :class:`_types.JSON` - Core level JSON type :class:`_postgresql.JSONB` .. versionchanged:: 1.1 :class:`_postgresql.JSON` is now a PostgreSQL- specific specialization of the new :class:`_types.JSON` type.

Class Comparator Define comparison operations for :class:`_types.JSON`.
Method __init__ Construct a :class:`_types.JSON` type.
Instance Variable astext_type Undocumented

Inherited from JSON:

Class JSONElementType Common function for index / path elements in a JSON expression.
Class JSONIndexType Placeholder for the datatype of a JSON index value.
Class JSONIntIndexType Placeholder for the datatype of a JSON index value.
Class JSONPathType Placeholder type for JSON path operations.
Class JSONStrIndexType Placeholder for the datatype of a JSON index value.
Method bind_processor Return a conversion function for processing bind values.
Method result_processor Return a conversion function for processing result row values.
Method should_evaluate_none.setter Undocumented
Constant NULL Describe the json value of NULL.
Class Variable __visit_name__ Undocumented
Class Variable hashable Flag, if False, means values from this type aren't hashable.
Instance Variable none_as_null Undocumented
Property python_type Return the Python type object expected to be returned by instances of this type, if known.
Property should_evaluate_none Alias of :attr:`_types.JSON.none_as_null`
Method _make_bind_processor Undocumented
Property _str_impl Undocumented

Inherited from TypeEngineMixin (via JSON, Indexable):

Method adapt Undocumented
Method dialect_impl Undocumented
Class Variable __slots__ Undocumented
Property _static_cache_key Undocumented

Inherited from TypeEngine (via JSON, Indexable, TypeEngineMixin):

Method __repr__ Undocumented
Method __str__ Undocumented
Method as_generic Return an instance of the generic type corresponding to this type using heuristic rule. The method may be overridden if this heuristic rule is not sufficient.
Method bind_expression Given a bind value (i.e. a :class:`.BindParameter` instance), return a SQL expression in its place.
Method coerce_compared_value Suggest a type for a 'coerced' Python value in an expression.
Method column_expression Given a SELECT column expression, return a wrapping SQL expression.
Method compare_against_backend Compare this type against the given backend type.
Method compare_values Compare two values for equality.
Method compile Produce a string-compiled form of this :class:`.TypeEngine`.
Method copy Undocumented
Method copy_value Undocumented
Method evaluates_none Return a copy of this type which has the :attr:`.should_evaluate_none` flag set to True.
Method get_dbapi_type Return the corresponding type object from the underlying DB-API, if any.
Method literal_processor Return a conversion function for processing literal values that are to be rendered directly without using binds.
Method with_variant Produce a copy of this type object that will utilize the given type when applied to the dialect of the given name.
Class Variable render_bind_cast Render bind casts for :attr:`.BindTyping.RENDER_CASTS` mode.
Class Variable render_literal_cast render casts when rendering a value as an inline literal, e.g. with :meth:`.TypeEngine.literal_processor`.
Class Variable sort_key_function A sorting function that can be passed as the key to sorted.
Static Method _to_instance Undocumented
Method _cached_bind_processor Return a dialect-specific bind processor for this type.
Method _cached_custom_processor return a dialect-specific processing object for custom purposes.
Method _cached_literal_processor Return a dialect-specific literal processor for this type.
Method _cached_result_processor Return a dialect-specific result processor for this type.
Method _compare_type_affinity Undocumented
Method _default_dialect Undocumented
Method _dialect_info Return a dialect-specific registry which caches a dialect-specific implementation, bind processing function, and one or more result processing functions.
Method _gen_dialect_impl Undocumented
Method _resolve_for_literal adjust this type given a literal Python value that will be stored in a bound parameter.
Method _resolve_for_python_type given a Python type (e.g. ``int``, ``str``, etc. ) return an instance of this :class:`.TypeEngine` that's appropriate for this type.
Method _unwrapped_dialect_impl Return the 'unwrapped' dialect impl for this type.
Class Variable _is_array Undocumented
Class Variable _is_table_value Undocumented
Class Variable _is_tuple_type Undocumented
Class Variable _is_type_decorator Undocumented
Class Variable _isnull Undocumented
Class Variable _sqla_type Undocumented
Property _generic_type_affinity Undocumented
Property _has_bind_expression memoized boolean, check if bind_expression is implemented.
Property _has_column_expression memoized boolean, check if column_expression is implemented.
Property _type_affinity Return a rudimental 'affinity' value expressing the general class of type.

Inherited from Visitable (via JSON, Indexable, TypeEngineMixin, TypeEngine):

Method __class_getitem__ Undocumented
Method __init_subclass__ Undocumented
Class Method _generate_compiler_dispatch Undocumented
Method _compiler_dispatch Undocumented
Class Variable _original_compiler_dispatch Undocumented
def __init__(self, none_as_null=False, astext_type=None): (source)
overrides sqlalchemy.sql.sqltypes.JSON.__init__

Construct a :class:`_types.JSON` type. :param none_as_null: if True, persist the value ``None`` as a SQL NULL value, not the JSON encoding of ``null``. Note that when this flag is False, the :func:`.null` construct can still be used to persist a NULL value:: from sqlalchemy import null conn.execute(table.insert(), data=null()) .. versionchanged:: 0.9.8 - Added ``none_as_null``, and :func:`.null` is now supported in order to persist a NULL value. .. seealso:: :attr:`_types.JSON.NULL` :param astext_type: the type to use for the :attr:`.JSON.Comparator.astext` accessor on indexed attributes. Defaults to :class:`_types.Text`. .. versionadded:: 1.1

astext_type = (source)

Undocumented