358 lines
12 KiB
Python
358 lines
12 KiB
Python
# postgresql/json.py
|
|
# Copyright (C) 2005-2015 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
|
|
|
|
import json
|
|
|
|
from .base import ischema_names
|
|
from ... import types as sqltypes
|
|
from ...sql.operators import custom_op
|
|
from ... import sql
|
|
from ...sql import elements, default_comparator
|
|
from ... import util
|
|
|
|
__all__ = ('JSON', 'JSONElement', 'JSONB')
|
|
|
|
|
|
class JSONElement(elements.BinaryExpression):
|
|
"""Represents accessing an element of a :class:`.JSON` value.
|
|
|
|
The :class:`.JSONElement` is produced whenever using the Python index
|
|
operator on an expression that has the type :class:`.JSON`::
|
|
|
|
expr = mytable.c.json_data['some_key']
|
|
|
|
The expression typically compiles to a JSON access such as ``col -> key``.
|
|
Modifiers are then available for typing behavior, including
|
|
:meth:`.JSONElement.cast` and :attr:`.JSONElement.astext`.
|
|
|
|
"""
|
|
|
|
def __init__(self, left, right, astext=False,
|
|
opstring=None, result_type=None):
|
|
self._astext = astext
|
|
if opstring is None:
|
|
if hasattr(right, '__iter__') and \
|
|
not isinstance(right, util.string_types):
|
|
opstring = "#>"
|
|
right = "{%s}" % (
|
|
", ".join(util.text_type(elem) for elem in right))
|
|
else:
|
|
opstring = "->"
|
|
|
|
self._json_opstring = opstring
|
|
operator = custom_op(opstring, precedence=5)
|
|
right = default_comparator._check_literal(
|
|
left, operator, right)
|
|
super(JSONElement, self).__init__(
|
|
left, right, operator, type_=result_type)
|
|
|
|
@property
|
|
def astext(self):
|
|
"""Convert this :class:`.JSONElement` to use the 'astext' operator
|
|
when evaluated.
|
|
|
|
E.g.::
|
|
|
|
select([data_table.c.data['some key'].astext])
|
|
|
|
.. seealso::
|
|
|
|
:meth:`.JSONElement.cast`
|
|
|
|
"""
|
|
if self._astext:
|
|
return self
|
|
else:
|
|
return JSONElement(
|
|
self.left,
|
|
self.right,
|
|
astext=True,
|
|
opstring=self._json_opstring + ">",
|
|
result_type=sqltypes.String(convert_unicode=True)
|
|
)
|
|
|
|
def cast(self, type_):
|
|
"""Convert this :class:`.JSONElement` to apply both the 'astext' operator
|
|
as well as an explicit type cast when evaluated.
|
|
|
|
E.g.::
|
|
|
|
select([data_table.c.data['some key'].cast(Integer)])
|
|
|
|
.. seealso::
|
|
|
|
:attr:`.JSONElement.astext`
|
|
|
|
"""
|
|
if not self._astext:
|
|
return self.astext.cast(type_)
|
|
else:
|
|
return sql.cast(self, type_)
|
|
|
|
|
|
class JSON(sqltypes.TypeEngine):
|
|
"""Represent the Postgresql JSON type.
|
|
|
|
The :class:`.JSON` type stores arbitrary JSON format data, e.g.::
|
|
|
|
data_table = Table('data_table', metadata,
|
|
Column('id', Integer, primary_key=True),
|
|
Column('data', JSON)
|
|
)
|
|
|
|
with engine.connect() as conn:
|
|
conn.execute(
|
|
data_table.insert(),
|
|
data = {"key1": "value1", "key2": "value2"}
|
|
)
|
|
|
|
:class:`.JSON` 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
|
|
|
|
"""
|
|
|
|
__visit_name__ = 'JSON'
|
|
|
|
def __init__(self, none_as_null=False):
|
|
"""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.
|
|
|
|
"""
|
|
self.none_as_null = none_as_null
|
|
|
|
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):
|
|
if isinstance(value, elements.Null) or (
|
|
value is None and self.none_as_null
|
|
):
|
|
return None
|
|
return json_serializer(value).encode(encoding)
|
|
else:
|
|
def process(value):
|
|
if isinstance(value, elements.Null) or (
|
|
value is None and self.none_as_null
|
|
):
|
|
return None
|
|
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):
|
|
if value is None:
|
|
return None
|
|
return json_deserializer(value.decode(encoding))
|
|
else:
|
|
def process(value):
|
|
if value is None:
|
|
return None
|
|
return json_deserializer(value)
|
|
return process
|
|
|
|
|
|
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"}
|
|
)
|
|
|
|
: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'
|
|
hashable = False
|
|
|
|
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):
|
|
# How does one do equality?? jsonb also has "=" eg.
|
|
# '[1,2,3]'::jsonb = '[1,2,3]'::jsonb
|
|
if isinstance(op, custom_op):
|
|
if op.opstring in ['?', '?&', '?|', '@>', '<@']:
|
|
return op, sqltypes.Boolean
|
|
if op.opstring == '->':
|
|
return op, sqltypes.Text
|
|
return sqltypes.Concatenable.Comparator.\
|
|
_adapt_expression(self, op, other_comparator)
|
|
|
|
def has_key(self, other):
|
|
"""Boolean expression. Test for presence of a key. Note that the
|
|
key may be a SQLA expression.
|
|
"""
|
|
return self.expr.op('?')(other)
|
|
|
|
def has_all(self, other):
|
|
"""Boolean expression. Test for presence of all keys in jsonb
|
|
"""
|
|
return self.expr.op('?&')(other)
|
|
|
|
def has_any(self, other):
|
|
"""Boolean expression. Test for presence of any key in jsonb
|
|
"""
|
|
return self.expr.op('?|')(other)
|
|
|
|
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.expr.op('@>')(other)
|
|
|
|
def contained_by(self, other):
|
|
"""Boolean expression. Test if keys are a proper subset of the
|
|
keys of the argument jsonb expression.
|
|
"""
|
|
return self.expr.op('<@')(other)
|
|
|
|
ischema_names['jsonb'] = JSONB
|