302 lines
9.6 KiB
Python
302 lines
9.6 KiB
Python
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# postgresql/json.py
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# Copyright (C) 2005-2018 the SQLAlchemy authors and contributors
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# <see AUTHORS file>
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#
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# This module is part of SQLAlchemy and is released under
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# the MIT License: http://www.opensource.org/licenses/mit-license.php
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from __future__ import absolute_import
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import json
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import collections
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from .base import ischema_names, colspecs
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from ... import types as sqltypes
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from ...sql import operators
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from ...sql import elements
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from ... import util
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__all__ = ('JSON', 'JSONB')
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idx_precedence = operators._PRECEDENCE[operators.json_getitem_op]
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ASTEXT = operators.custom_op(
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"->>", precedence=idx_precedence, natural_self_precedent=True,
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eager_grouping=True
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)
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JSONPATH_ASTEXT = operators.custom_op(
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"#>>", precedence=idx_precedence, natural_self_precedent=True,
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eager_grouping=True
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)
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HAS_KEY = operators.custom_op(
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"?", precedence=idx_precedence, natural_self_precedent=True,
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eager_grouping=True
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)
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HAS_ALL = operators.custom_op(
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"?&", precedence=idx_precedence, natural_self_precedent=True,
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eager_grouping=True
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)
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HAS_ANY = operators.custom_op(
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"?|", precedence=idx_precedence, natural_self_precedent=True,
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eager_grouping=True
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)
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CONTAINS = operators.custom_op(
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"@>", precedence=idx_precedence, natural_self_precedent=True,
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eager_grouping=True
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)
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CONTAINED_BY = operators.custom_op(
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"<@", precedence=idx_precedence, natural_self_precedent=True,
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eager_grouping=True
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)
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class JSONPathType(sqltypes.JSON.JSONPathType):
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def bind_processor(self, dialect):
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super_proc = self.string_bind_processor(dialect)
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def process(value):
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assert isinstance(value, collections.Sequence)
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tokens = [util.text_type(elem)for elem in value]
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value = "{%s}" % (", ".join(tokens))
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if super_proc:
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value = super_proc(value)
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return value
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return process
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def literal_processor(self, dialect):
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super_proc = self.string_literal_processor(dialect)
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def process(value):
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assert isinstance(value, collections.Sequence)
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tokens = [util.text_type(elem)for elem in value]
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value = "{%s}" % (", ".join(tokens))
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if super_proc:
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value = super_proc(value)
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return value
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return process
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colspecs[sqltypes.JSON.JSONPathType] = JSONPathType
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class JSON(sqltypes.JSON):
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"""Represent the PostgreSQL JSON type.
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This type is a specialization of the Core-level :class:`.types.JSON`
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type. Be sure to read the documentation for :class:`.types.JSON` for
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important tips regarding treatment of NULL values and ORM use.
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.. versionchanged:: 1.1 :class:`.postgresql.JSON` is now a PostgreSQL-
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specific specialization of the new :class:`.types.JSON` type.
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The operators provided by the PostgreSQL version of :class:`.JSON`
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include:
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* Index operations (the ``->`` operator)::
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data_table.c.data['some key']
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data_table.c.data[5]
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* Index operations returning text (the ``->>`` operator)::
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data_table.c.data['some key'].astext == 'some value'
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* Index operations with CAST
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(equivalent to ``CAST(col ->> ['some key'] AS <type>)``)::
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data_table.c.data['some key'].astext.cast(Integer) == 5
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* Path index operations (the ``#>`` operator)::
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data_table.c.data[('key_1', 'key_2', 5, ..., 'key_n')]
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* Path index operations returning text (the ``#>>`` operator)::
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data_table.c.data[('key_1', 'key_2', 5, ..., 'key_n')].astext == \
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'some value'
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.. versionchanged:: 1.1 The :meth:`.ColumnElement.cast` operator on
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JSON objects now requires that the :attr:`.JSON.Comparator.astext`
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modifier be called explicitly, if the cast works only from a textual
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string.
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Index operations return an expression object whose type defaults to
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:class:`.JSON` by default, so that further JSON-oriented instructions
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may be called upon the result type.
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Custom serializers and deserializers are specified at the dialect level,
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that is using :func:`.create_engine`. The reason for this is that when
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using psycopg2, the DBAPI only allows serializers at the per-cursor
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or per-connection level. E.g.::
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engine = create_engine("postgresql://scott:tiger@localhost/test",
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json_serializer=my_serialize_fn,
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json_deserializer=my_deserialize_fn
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)
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When using the psycopg2 dialect, the json_deserializer is registered
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against the database using ``psycopg2.extras.register_default_json``.
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.. seealso::
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:class:`.types.JSON` - Core level JSON type
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:class:`.JSONB`
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"""
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astext_type = sqltypes.Text()
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def __init__(self, none_as_null=False, astext_type=None):
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"""Construct a :class:`.JSON` type.
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:param none_as_null: if True, persist the value ``None`` as a
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SQL NULL value, not the JSON encoding of ``null``. Note that
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when this flag is False, the :func:`.null` construct can still
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be used to persist a NULL value::
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from sqlalchemy import null
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conn.execute(table.insert(), data=null())
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.. versionchanged:: 0.9.8 - Added ``none_as_null``, and :func:`.null`
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is now supported in order to persist a NULL value.
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.. seealso::
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:attr:`.JSON.NULL`
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:param astext_type: the type to use for the
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:attr:`.JSON.Comparator.astext`
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accessor on indexed attributes. Defaults to :class:`.types.Text`.
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.. versionadded:: 1.1
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"""
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super(JSON, self).__init__(none_as_null=none_as_null)
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if astext_type is not None:
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self.astext_type = astext_type
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class Comparator(sqltypes.JSON.Comparator):
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"""Define comparison operations for :class:`.JSON`."""
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@property
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def astext(self):
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"""On an indexed expression, use the "astext" (e.g. "->>")
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conversion when rendered in SQL.
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E.g.::
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select([data_table.c.data['some key'].astext])
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.. seealso::
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:meth:`.ColumnElement.cast`
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"""
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if isinstance(self.expr.right.type, sqltypes.JSON.JSONPathType):
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return self.expr.left.operate(
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JSONPATH_ASTEXT,
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self.expr.right, result_type=self.type.astext_type)
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else:
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return self.expr.left.operate(
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ASTEXT, self.expr.right, result_type=self.type.astext_type)
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comparator_factory = Comparator
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colspecs[sqltypes.JSON] = JSON
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ischema_names['json'] = JSON
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class JSONB(JSON):
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"""Represent the PostgreSQL JSONB type.
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The :class:`.JSONB` type stores arbitrary JSONB format data, e.g.::
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data_table = Table('data_table', metadata,
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Column('id', Integer, primary_key=True),
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Column('data', JSONB)
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)
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with engine.connect() as conn:
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conn.execute(
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data_table.insert(),
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data = {"key1": "value1", "key2": "value2"}
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)
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The :class:`.JSONB` type includes all operations provided by
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:class:`.JSON`, including the same behaviors for indexing operations.
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It also adds additional operators specific to JSONB, including
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:meth:`.JSONB.Comparator.has_key`, :meth:`.JSONB.Comparator.has_all`,
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:meth:`.JSONB.Comparator.has_any`, :meth:`.JSONB.Comparator.contains`,
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and :meth:`.JSONB.Comparator.contained_by`.
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Like the :class:`.JSON` type, the :class:`.JSONB` type does not detect
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in-place changes when used with the ORM, unless the
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:mod:`sqlalchemy.ext.mutable` extension is used.
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Custom serializers and deserializers
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are shared with the :class:`.JSON` class, using the ``json_serializer``
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and ``json_deserializer`` keyword arguments. These must be specified
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at the dialect level using :func:`.create_engine`. When using
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psycopg2, the serializers are associated with the jsonb type using
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``psycopg2.extras.register_default_jsonb`` on a per-connection basis,
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in the same way that ``psycopg2.extras.register_default_json`` is used
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to register these handlers with the json type.
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.. versionadded:: 0.9.7
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.. seealso::
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:class:`.JSON`
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"""
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__visit_name__ = 'JSONB'
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class Comparator(JSON.Comparator):
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"""Define comparison operations for :class:`.JSON`."""
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def has_key(self, other):
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"""Boolean expression. Test for presence of a key. Note that the
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key may be a SQLA expression.
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"""
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return self.operate(HAS_KEY, other, result_type=sqltypes.Boolean)
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def has_all(self, other):
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"""Boolean expression. Test for presence of all keys in jsonb
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"""
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return self.operate(HAS_ALL, other, result_type=sqltypes.Boolean)
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def has_any(self, other):
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"""Boolean expression. Test for presence of any key in jsonb
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"""
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return self.operate(HAS_ANY, other, result_type=sqltypes.Boolean)
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def contains(self, other, **kwargs):
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"""Boolean expression. Test if keys (or array) are a superset
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of/contained the keys of the argument jsonb expression.
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"""
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return self.operate(CONTAINS, other, result_type=sqltypes.Boolean)
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def contained_by(self, other):
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"""Boolean expression. Test if keys are a proper subset of the
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keys of the argument jsonb expression.
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"""
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return self.operate(
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CONTAINED_BY, other, result_type=sqltypes.Boolean)
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comparator_factory = Comparator
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ischema_names['jsonb'] = JSONB
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