Current File : //opt/alt/python37/lib64/python3.7/site-packages/sqlalchemy/dialects/postgresql/json.py
# postgresql/json.py
# Copyright (C) 2005-2019 the SQLAlchemy authors and contributors
# <see AUTHORS file>
#
# This module is part of SQLAlchemy and is released under
# the MIT License: http://www.opensource.org/licenses/mit-license.php
from __future__ import absolute_import
from .base import colspecs
from .base import ischema_names
from ... import types as sqltypes
from ... import util
from ...sql import operators
__all__ = ("JSON", "JSONB")
idx_precedence = operators._PRECEDENCE[operators.json_getitem_op]
ASTEXT = operators.custom_op(
"->>",
precedence=idx_precedence,
natural_self_precedent=True,
eager_grouping=True,
)
JSONPATH_ASTEXT = operators.custom_op(
"#>>",
precedence=idx_precedence,
natural_self_precedent=True,
eager_grouping=True,
)
HAS_KEY = operators.custom_op(
"?",
precedence=idx_precedence,
natural_self_precedent=True,
eager_grouping=True,
)
HAS_ALL = operators.custom_op(
"?&",
precedence=idx_precedence,
natural_self_precedent=True,
eager_grouping=True,
)
HAS_ANY = operators.custom_op(
"?|",
precedence=idx_precedence,
natural_self_precedent=True,
eager_grouping=True,
)
CONTAINS = operators.custom_op(
"@>",
precedence=idx_precedence,
natural_self_precedent=True,
eager_grouping=True,
)
CONTAINED_BY = operators.custom_op(
"<@",
precedence=idx_precedence,
natural_self_precedent=True,
eager_grouping=True,
)
class JSONPathType(sqltypes.JSON.JSONPathType):
def bind_processor(self, dialect):
super_proc = self.string_bind_processor(dialect)
def process(value):
assert isinstance(value, util.collections_abc.Sequence)
tokens = [util.text_type(elem) for elem in value]
value = "{%s}" % (", ".join(tokens))
if super_proc:
value = super_proc(value)
return value
return process
def literal_processor(self, dialect):
super_proc = self.string_literal_processor(dialect)
def process(value):
assert isinstance(value, util.collections_abc.Sequence)
tokens = [util.text_type(elem) for elem in value]
value = "{%s}" % (", ".join(tokens))
if super_proc:
value = super_proc(value)
return value
return process
colspecs[sqltypes.JSON.JSONPathType] = JSONPathType
class JSON(sqltypes.JSON):
"""Represent the PostgreSQL JSON type.
This type is a specialization of the Core-level :class:`.types.JSON`
type. Be sure to read the documentation for :class:`.types.JSON` for
important tips regarding treatment of NULL values and ORM use.
.. versionchanged:: 1.1 :class:`.postgresql.JSON` is now a PostgreSQL-
specific specialization of the new :class:`.types.JSON` type.
The operators provided by the PostgreSQL version of :class:`.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'
* Index operations with CAST
(equivalent to ``CAST(col ->> ['some key'] AS <type>)``)::
data_table.c.data['some key'].astext.cast(Integer) == 5
* 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:`.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:`.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:`.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``.
.. seealso::
:class:`.types.JSON` - Core level JSON type
:class:`.JSONB`
""" # noqa
astext_type = sqltypes.Text()
def __init__(self, none_as_null=False, astext_type=None):
"""Construct a :class:`.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:`.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
"""
super(JSON, self).__init__(none_as_null=none_as_null)
if astext_type is not None:
self.astext_type = astext_type
class Comparator(sqltypes.JSON.Comparator):
"""Define comparison operations for :class:`.JSON`."""
@property
def astext(self):
"""On an indexed expression, use the "astext" (e.g. "->>")
conversion when rendered in SQL.
E.g.::
select([data_table.c.data['some key'].astext])
.. seealso::
:meth:`.ColumnElement.cast`
"""
if isinstance(self.expr.right.type, sqltypes.JSON.JSONPathType):
return self.expr.left.operate(
JSONPATH_ASTEXT,
self.expr.right,
result_type=self.type.astext_type,
)
else:
return self.expr.left.operate(
ASTEXT, self.expr.right, result_type=self.type.astext_type
)
comparator_factory = Comparator
colspecs[sqltypes.JSON] = JSON
ischema_names["json"] = JSON
class JSONB(JSON):
"""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"}
)
The :class:`.JSONB` type includes all operations provided by
:class:`.JSON`, including the same behaviors for indexing operations.
It also adds additional operators specific to JSONB, including
:meth:`.JSONB.Comparator.has_key`, :meth:`.JSONB.Comparator.has_all`,
:meth:`.JSONB.Comparator.has_any`, :meth:`.JSONB.Comparator.contains`,
and :meth:`.JSONB.Comparator.contained_by`.
Like the :class:`.JSON` type, the :class:`.JSONB` type does not detect
in-place changes when used with the ORM, unless the
:mod:`sqlalchemy.ext.mutable` extension is used.
Custom serializers and deserializers
are shared with the :class:`.JSON` class, using the ``json_serializer``
and ``json_deserializer`` keyword arguments. These must be specified
at the dialect level using :func:`.create_engine`. When using
psycopg2, the serializers are associated with the jsonb type using
``psycopg2.extras.register_default_jsonb`` on a per-connection basis,
in the same way that ``psycopg2.extras.register_default_json`` is used
to register these handlers with the json type.
.. versionadded:: 0.9.7
.. seealso::
:class:`.JSON`
"""
__visit_name__ = "JSONB"
class Comparator(JSON.Comparator):
"""Define comparison operations for :class:`.JSON`."""
def has_key(self, other):
"""Boolean expression. Test for presence of a key. Note that the
key may be a SQLA expression.
"""
return self.operate(HAS_KEY, other, result_type=sqltypes.Boolean)
def has_all(self, other):
"""Boolean expression. Test for presence of all keys in jsonb
"""
return self.operate(HAS_ALL, other, result_type=sqltypes.Boolean)
def has_any(self, other):
"""Boolean expression. Test for presence of any key in jsonb
"""
return self.operate(HAS_ANY, other, result_type=sqltypes.Boolean)
def contains(self, other, **kwargs):
"""Boolean expression. Test if keys (or array) are a superset
of/contained the keys of the argument jsonb expression.
"""
return self.operate(CONTAINS, other, result_type=sqltypes.Boolean)
def contained_by(self, other):
"""Boolean expression. Test if keys are a proper subset of the
keys of the argument jsonb expression.
"""
return self.operate(
CONTAINED_BY, other, result_type=sqltypes.Boolean
)
comparator_factory = Comparator
ischema_names["jsonb"] = JSONB
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