288 lines
8.5 KiB
Python
288 lines
8.5 KiB
Python
# -*- coding: utf-8 -*-
|
|
#
|
|
# python-json-patch - An implementation of the JSON Patch format
|
|
# https://github.com/stefankoegl/python-json-patch
|
|
#
|
|
# Copyright (c) 2011 Stefan Kögl <stefan@skoegl.net>
|
|
# All rights reserved.
|
|
#
|
|
# Redistribution and use in source and binary forms, with or without
|
|
# modification, are permitted provided that the following conditions
|
|
# are met:
|
|
#
|
|
# 1. Redistributions of source code must retain the above copyright
|
|
# notice, this list of conditions and the following disclaimer.
|
|
# 2. Redistributions in binary form must reproduce the above copyright
|
|
# notice, this list of conditions and the following disclaimer in the
|
|
# documentation and/or other materials provided with the distribution.
|
|
# 3. The name of the author may not be used to endorse or promote products
|
|
# derived from this software without specific prior written permission.
|
|
#
|
|
# THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
|
|
# IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
|
|
# OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
|
|
# IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
|
|
# INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
|
|
# NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
|
|
# DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
|
|
# THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
|
|
# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
|
|
# THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
|
|
#
|
|
|
|
"""Apply JSON-Patches according to http://tools.ietf.org/html/draft-pbryan-json-patch-04"""
|
|
|
|
# Will be parsed by setup.py to determine package metadata
|
|
__author__ = 'Stefan Kögl <stefan@skoegl.net>'
|
|
__version__ = '0.1'
|
|
__website__ = 'https://github.com/stefankoegl/python-json-patch'
|
|
__license__ = 'Modified BSD License'
|
|
|
|
|
|
import copy
|
|
import json
|
|
|
|
|
|
class JsonPatchException(Exception):
|
|
pass
|
|
|
|
|
|
class JsonPatchConflict(JsonPatchException):
|
|
pass
|
|
|
|
|
|
def apply_patch(doc, patch):
|
|
"""
|
|
>>> obj = { 'baz': 'qux', 'foo': 'bar' }
|
|
>>> patch = [ { 'remove': '/baz' } ]
|
|
>>> apply_patch(obj, patch)
|
|
{'foo': 'bar'}
|
|
"""
|
|
|
|
p = JsonPatch(patch)
|
|
return p.apply(doc)
|
|
|
|
|
|
class JsonPatch(object):
|
|
""" A JSON Patch is a list of Patch Operations """
|
|
|
|
def __init__(self, patch):
|
|
self.patch = patch
|
|
|
|
self.OPERATIONS = {
|
|
'remove': RemoveOperation,
|
|
'add': AddOperation,
|
|
'replace': ReplaceOperation,
|
|
'move': MoveOperation,
|
|
'test': TestOperation
|
|
}
|
|
|
|
|
|
@classmethod
|
|
def from_string(cls, patch_str):
|
|
patch = json.loads(patch_str)
|
|
return cls(patch)
|
|
|
|
|
|
def apply(self, obj):
|
|
""" Applies the patch to a copy of the given object """
|
|
|
|
obj = copy.deepcopy(obj)
|
|
|
|
for operation in self.patch:
|
|
op = self._get_operation(operation)
|
|
op.apply(obj)
|
|
|
|
return obj
|
|
|
|
|
|
def _get_operation(self, operation):
|
|
for action, op_cls in self.OPERATIONS.items():
|
|
if action in operation:
|
|
location = operation[action]
|
|
op = op_cls(location, operation)
|
|
return op
|
|
|
|
raise JsonPatchException("invalid operation '%s'" % operation)
|
|
|
|
|
|
|
|
class PatchOperation(object):
|
|
""" A single operation inside a JSON Patch """
|
|
|
|
def __init__(self, location, operation):
|
|
self.location = location
|
|
self.operation = operation
|
|
|
|
|
|
def locate(self, obj, location, last_must_exist=True):
|
|
""" Walks through the object according to location
|
|
|
|
Returns the last step as (sub-object, last location-step) """
|
|
|
|
parts = location.split('/')
|
|
if parts.pop(0) != '':
|
|
raise JsonPatchException('location must starts with /')
|
|
|
|
for part in parts[:-1]:
|
|
obj, loc_part = self._step(obj, part)
|
|
|
|
_, last_loc = self._step(obj, parts[-1], must_exist=last_must_exist)
|
|
return obj, last_loc
|
|
|
|
|
|
def _step(self, obj, loc_part, must_exist=True):
|
|
""" Goes one step in a locate() call """
|
|
|
|
# Its not clear if a location "1" should be considered as 1 or "1"
|
|
# We prefer the integer-variant if possible
|
|
part_variants = self._try_parse(loc_part) + [loc_part]
|
|
|
|
for variant in part_variants:
|
|
try:
|
|
return obj[variant], variant
|
|
except:
|
|
continue
|
|
|
|
if must_exist:
|
|
raise JsonPatchConflict('key %s not found' % loc_part)
|
|
else:
|
|
return obj, part_variants[0]
|
|
|
|
|
|
@staticmethod
|
|
def _try_parse(val, cls=int):
|
|
try:
|
|
return [cls(val)]
|
|
except:
|
|
return []
|
|
|
|
|
|
class RemoveOperation(PatchOperation):
|
|
""" Removes an object property or an array element
|
|
|
|
>>> obj = { 'baz': 'qux', 'foo': 'bar' }
|
|
>>> patch = JsonPatch( [ { 'remove': '/baz' } ] )
|
|
>>> patch.apply(obj)
|
|
{'foo': 'bar'}
|
|
|
|
>>> obj = { 'foo': [ 'bar', 'qux', 'baz' ] }
|
|
>>> patch = JsonPatch( [ { "remove": "/foo/1" } ] )
|
|
>>> patch.apply(obj)
|
|
{'foo': ['bar', 'baz']}
|
|
"""
|
|
|
|
def apply(self, obj):
|
|
subobj, part = self.locate(obj, self.location)
|
|
del subobj[part]
|
|
|
|
|
|
class AddOperation(PatchOperation):
|
|
""" Adds an object property or an array element
|
|
|
|
>>> obj = { "foo": "bar" }
|
|
>>> patch = JsonPatch([ { "add": "/baz", "value": "qux" } ])
|
|
>>> patch.apply(obj)
|
|
{'foo': 'bar', 'baz': 'qux'}
|
|
|
|
>>> obj = { "foo": [ "bar", "baz" ] }
|
|
>>> patch = JsonPatch([ { "add": "/foo/1", "value": "qux" } ])
|
|
>>> patch.apply(obj)
|
|
{'foo': ['bar', 'qux', 'baz']}
|
|
"""
|
|
|
|
def apply(self, obj):
|
|
value = self.operation["value"]
|
|
subobj, part = self.locate(obj, self.location, last_must_exist=False)
|
|
|
|
if isinstance(subobj, list):
|
|
if part > len(subobj) or part < 0:
|
|
raise JsonPatchConflict("can't insert outside of list")
|
|
|
|
subobj.insert(part, value)
|
|
|
|
elif isinstance(subobj, dict):
|
|
if part in subobj:
|
|
raise JsonPatchConflict("object '%s' already exists" % part)
|
|
|
|
subobj[part] = value
|
|
|
|
else:
|
|
raise JsonPatchConflict("can't add to type '%s'" % subobj.__class__.__name__)
|
|
|
|
|
|
class ReplaceOperation(PatchOperation):
|
|
""" Replaces a value
|
|
|
|
>>> obj = { "baz": "qux", "foo": "bar" }
|
|
>>> patch = JsonPatch([ { "replace": "/baz", "value": "boo" } ])
|
|
>>> patch.apply(obj)
|
|
{'foo': 'bar', 'baz': 'boo'}
|
|
"""
|
|
|
|
def apply(self, obj):
|
|
value = self.operation["value"]
|
|
subobj, part = self.locate(obj, self.location)
|
|
|
|
if isinstance(subobj, list):
|
|
if part > len(subobj) or part < 0:
|
|
raise JsonPatchConflict("can't replace outside of list")
|
|
|
|
elif isinstance(subobj, dict):
|
|
if not part in subobj:
|
|
raise JsonPatchConflict("can't replace non-existant object '%s'" % part)
|
|
|
|
else:
|
|
raise JsonPatchConflict("can't replace in type '%s'" % subobj.__class__.__name__)
|
|
|
|
subobj[part] = value
|
|
|
|
|
|
class MoveOperation(PatchOperation):
|
|
""" Moves a value
|
|
|
|
>>> obj = {'foo': {'bar': 'baz', 'waldo': 'fred'}, 'qux': {'corge': 'grault'}}
|
|
>>> patch = JsonPatch([{'move': '/foo/waldo', 'to': '/qux/thud'}])
|
|
>>> patch.apply(obj)
|
|
{'qux': {'thud': 'fred', 'corge': 'grault'}, 'foo': {'bar': 'baz'}}
|
|
|
|
>>> obj = {'foo': ['all', 'grass', 'cows', 'eat']}
|
|
>>> patch = JsonPatch([{'move': '/foo/1', 'to': '/foo/3'}])
|
|
>>> patch.apply(obj)
|
|
{'foo': ['all', 'cows', 'eat', 'grass']}
|
|
"""
|
|
|
|
def apply(self, obj):
|
|
subobj, part = self.locate(obj, self.location)
|
|
value = subobj[part]
|
|
RemoveOperation(self.location, self.operation).apply(obj)
|
|
AddOperation(self.operation['to'], {'value': value}).apply(obj)
|
|
|
|
|
|
class TestOperation(PatchOperation):
|
|
""" Test value by specified location
|
|
|
|
>>> obj = {'baz': 'qux', 'foo': ['a', 2, 'c']}
|
|
>>> patch = JsonPatch([
|
|
... {'test': '/baz', 'value': 'qux'},
|
|
... {'test': '/foo/1', 'value': 2}
|
|
... ])
|
|
>>> patch.apply(obj)
|
|
{'foo': ['a', 2, 'c'], 'baz': 'qux'}
|
|
|
|
>>> patch = JsonPatch([
|
|
... {'test': '/foo/1', 'value': 'BOOM!'}
|
|
... ])
|
|
>>> try:
|
|
... patch.apply(obj)
|
|
... except AssertionError:
|
|
... pass
|
|
... else:
|
|
... assert False, 'test should fall'
|
|
"""
|
|
|
|
def apply(self, obj):
|
|
value = self.operation['value']
|
|
subobj, part = self.locate(obj, self.location)
|
|
assert subobj[part] == value
|