python-json-patch/jsonpatch.py at hypothesis · vavanade/python-json-patch · GitHub

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# -*- coding: utf-8 -*-

# python-json-patch - An implementation of the JSON Patch format

# https://github.com/stefankoegl/python-json-patch

# 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 (RFC 6902) """

from __future__ import unicode_literals

import collections

import copy

import functools

import inspect

import itertools

import json

import sys

from jsonpointer import JsonPointer, JsonPointerException

_ST_ADD = 0

_ST_REMOVE = 1

try:

from collections.abc import MutableMapping, MutableSequence

except ImportError:

from collections import MutableMapping, MutableSequence

str = unicode

# Will be parsed by setup.py to determine package metadata

__author__ = 'Stefan Kögl <stefan@skoegl.net>'

__version__ = '1.21'

__website__ = 'https://github.com/stefankoegl/python-json-patch'

__license__ = 'Modified BSD License'

# pylint: disable=E0611,W0404

if sys.version_info >= (3, 0):

basestring = (bytes, str) # pylint: disable=C0103,W0622

class JsonPatchException(Exception):

"""Base Json Patch exception"""

class InvalidJsonPatch(JsonPatchException):

""" Raised if an invalid JSON Patch is created """

class JsonPatchConflict(JsonPatchException):

"""Raised if patch could not be applied due to conflict situation such as:

- attempt to add object key then it already exists;

- attempt to operate with nonexistence object key;

- attempt to insert value to array at position beyond of it size;

- etc.

"""

class JsonPatchTestFailed(JsonPatchException, AssertionError):

""" A Test operation failed """

def multidict(ordered_pairs):

"""Convert duplicate keys values to lists."""

# read all values into lists

mdict = collections.defaultdict(list)

for key, value in ordered_pairs:

mdict[key].append(value)

return dict(

# unpack lists that have only 1 item

(key, values[0] if len(values) == 1 else values)

for key, values in mdict.items()

)

# The "object_pairs_hook" parameter is used to handle duplicate keys when

# loading a JSON object.

_jsonloads = functools.partial(json.loads, object_pairs_hook=multidict)

def apply_patch(doc, patch, in_place=False):

"""Apply list of patches to specified json document.

:param doc: Document object.

:type doc: dict

:param patch: JSON patch as list of dicts or raw JSON-encoded string.

:type patch: list or str

:param in_place: While :const:`True` patch will modify target document.

By default patch will be applied to document copy.

:type in_place: bool

:return: Patched document object.

:rtype: dict

>>> doc = {'foo': 'bar'}

>>> patch = [{'op': 'add', 'path': '/baz', 'value': 'qux'}]

>>> other = apply_patch(doc, patch)

>>> doc is not other

True

>>> other == {'foo': 'bar', 'baz': 'qux'}

True

>>> patch = [{'op': 'add', 'path': '/baz', 'value': 'qux'}]

>>> apply_patch(doc, patch, in_place=True) == {'foo': 'bar', 'baz': 'qux'}

True

>>> doc == other

True

"""

if isinstance(patch, basestring):

patch = JsonPatch.from_string(patch)

else:

patch = JsonPatch(patch)

return patch.apply(doc, in_place)

def make_patch(src, dst):

"""Generates patch by comparing of two document objects. Actually is

a proxy to :meth:`JsonPatch.from_diff` method.

:param src: Data source document object.

:type src: dict

:param dst: Data source document object.

:type dst: dict

>>> src = {'foo': 'bar', 'numbers': [1, 3, 4, 8]}

>>> dst = {'baz': 'qux', 'numbers': [1, 4, 7]}

>>> patch = make_patch(src, dst)

>>> new = patch.apply(src)

>>> new == dst

True

"""

return JsonPatch.from_diff(src, dst)

class JsonPatch(object):

"""A JSON Patch is a list of Patch Operations.

>>> patch = JsonPatch([

... {'op': 'add', 'path': '/foo', 'value': 'bar'},

... {'op': 'add', 'path': '/baz', 'value': [1, 2, 3]},

... {'op': 'remove', 'path': '/baz/1'},

... {'op': 'test', 'path': '/baz', 'value': [1, 3]},

... {'op': 'replace', 'path': '/baz/0', 'value': 42},

... {'op': 'remove', 'path': '/baz/1'},

... ])

>>> doc = {}

>>> result = patch.apply(doc)

>>> expected = {'foo': 'bar', 'baz': [42]}

>>> result == expected

True

JsonPatch object is iterable, so you could easily access to each patch

statement in loop:

>>> lpatch = list(patch)

>>> expected = {'op': 'add', 'path': '/foo', 'value': 'bar'}

>>> lpatch[0] == expected

True

>>> lpatch == patch.patch

True

Also JsonPatch could be converted directly to :class:`bool` if it contains

any operation statements:

>>> bool(patch)

True

>>> bool(JsonPatch([]))

False

This behavior is very handy with :func:`make_patch` to write more readable

code:

>>> old = {'foo': 'bar', 'numbers': [1, 3, 4, 8]}

>>> new = {'baz': 'qux', 'numbers': [1, 4, 7]}

>>> patch = make_patch(old, new)

>>> if patch:

... # document have changed, do something useful

... patch.apply(old) #doctest: +ELLIPSIS

{...}

"""

def __init__(self, patch):

self.patch = patch

self.operations = {

'remove': RemoveOperation,

'add': AddOperation,

'replace': ReplaceOperation,

'move': MoveOperation,

'test': TestOperation,

'copy': CopyOperation,

}

def __str__(self):

"""str(self) -> self.to_string()"""

return self.to_string()

def __bool__(self):

return bool(self.patch)

__nonzero__ = __bool__

def __iter__(self):

return iter(self.patch)

def __hash__(self):

return hash(tuple(self._ops))

def __eq__(self, other):

if not isinstance(other, JsonPatch):

return False

return self._ops == other._ops

def __ne__(self, other):

return not(self == other)

@classmethod

def from_string(cls, patch_str):

"""Creates JsonPatch instance from string source.

:param patch_str: JSON patch as raw string.

:type patch_str: str

:return: :class:`JsonPatch` instance.

"""

patch = _jsonloads(patch_str)

return cls(patch)

@classmethod

def from_diff(cls, src, dst, optimization=True):

"""Creates JsonPatch instance based on comparing of two document

objects. Json patch would be created for `src` argument against `dst`

one.

:param src: Data source document object.

:type src: dict

:param dst: Data source document object.

:type dst: dict

:return: :class:`JsonPatch` instance.

>>> src = {'foo': 'bar', 'numbers': [1, 3, 4, 8]}

>>> dst = {'baz': 'qux', 'numbers': [1, 4, 7]}

>>> patch = JsonPatch.from_diff(src, dst)

>>> new = patch.apply(src)

>>> new == dst

True

"""

builder = DiffBuilder(src, dst)

ops = list(builder.execute())

return cls(ops)

def to_string(self):

"""Returns patch set as JSON string."""

return json.dumps(self.patch)

@property

def _ops(self):

return tuple(map(self._get_operation, self.patch))

def apply(self, obj, in_place=False):

"""Applies the patch to given object.

:param obj: Document object.

:type obj: dict

:param in_place: Tweaks way how patch would be applied - directly to

specified `obj` or to his copy.

:type in_place: bool

:return: Modified `obj`.

"""

if not in_place:

obj = copy.deepcopy(obj)

for operation in self._ops:

obj = operation.apply(obj)

return obj

def _get_operation(self, operation):

if 'op' not in operation:

raise InvalidJsonPatch("Operation does not contain 'op' member")

op = operation['op']

if not isinstance(op, basestring):

raise InvalidJsonPatch("Operation must be a string")

if op not in self.operations:

raise InvalidJsonPatch("Unknown operation {0!r}".format(op))

cls = self.operations[op]

return cls(operation)

class PatchOperation(object):

"""A single operation inside a JSON Patch."""

def __init__(self, operation):

self.location = operation['path']

self.pointer = JsonPointer(self.location)

self.operation = operation

def apply(self, obj):

"""Abstract method that applies patch operation to specified object."""

raise NotImplementedError('should implement patch operation.')

def __hash__(self):

return hash(frozenset(self.operation.items()))

def __eq__(self, other):

if not isinstance(other, PatchOperation):

return False

return self.operation == other.operation

def __ne__(self, other):

return not(self == other)

@property

def path(self):

return '/'.join(self.pointer.parts[:-1])

@property

def key(self):

try:

return int(self.pointer.parts[-1])

except ValueError:

return self.pointer.parts[-1]

@key.setter

def key(self, value):

self.pointer.parts[-1] = str(value)

self.location = self.pointer.path

self.operation['path'] = self.location

class RemoveOperation(PatchOperation):

"""Removes an object property or an array element."""

def apply(self, obj):

subobj, part = self.pointer.to_last(obj)

try:

del subobj[part]

except (KeyError, IndexError) as ex:

msg = "can't remove non-existent object '{0}'".format(part)

raise JsonPatchConflict(msg)

return obj

def _on_undo_remove(self, path, key):

if self.path == path:

if self.key >= key:

self.key += 1

else:

key -= 1

return key

def _on_undo_add(self, path, key):

if self.path == path:

if self.key > key:

self.key -= 1

else:

key -= 1

return key

class AddOperation(PatchOperation):

"""Adds an object property or an array element."""

def apply(self, obj):

try:

value = self.operation["value"]

except KeyError as ex:

raise InvalidJsonPatch(

"The operation does not contain a 'value' member")

subobj, part = self.pointer.to_last(obj)

if isinstance(subobj, MutableSequence):

if part == '-':

subobj.append(value) # pylint: disable=E1103

elif part > len(subobj) or part < 0:

raise JsonPatchConflict("can't insert outside of list")

else:

subobj.insert(part, value) # pylint: disable=E1103

elif isinstance(subobj, MutableMapping):

if part is None:

obj = value # we're replacing the root

else:

subobj[part] = value

else:

raise TypeError("invalid document type {0}".format(type(subobj)))

return obj

def _on_undo_remove(self, path, key):

if self.path == path:

if self.key > key:

self.key += 1

else:

key += 1

return key

def _on_undo_add(self, path, key):

if self.path == path:

if self.key > key:

self.key -= 1

else:

key += 1

return key

class ReplaceOperation(PatchOperation):

"""Replaces an object property or an array element by new value."""

def apply(self, obj):

try:

value = self.operation["value"]

except KeyError as ex:

raise InvalidJsonPatch(

"The operation does not contain a 'value' member")

subobj, part = self.pointer.to_last(obj)

if part is None:

return value

if isinstance(subobj, MutableSequence):

if part > len(subobj) or part < 0:

raise JsonPatchConflict("can't replace outside of list")

elif isinstance(subobj, MutableMapping):

if part not in subobj:

msg = "can't replace non-existent object '{0}'".format(part)

raise JsonPatchConflict(msg)

else:

raise TypeError("invalid document type {0}".format(type(subobj)))

subobj[part] = value

return obj

def _on_undo_remove(self, path, key):

return key

def _on_undo_add(self, path, key):

return key

class MoveOperation(PatchOperation):

"""Moves an object property or an array element to new location."""

def apply(self, obj):

try:

from_ptr = JsonPointer(self.operation['from'])

except KeyError as ex:

raise InvalidJsonPatch(

"The operation does not contain a 'from' member")

subobj, part = from_ptr.to_last(obj)

try:

value = subobj[part]

except (KeyError, IndexError) as ex:

raise JsonPatchConflict(str(ex))

# If source and target are equal, this is a no-op

if self.pointer == from_ptr:

return obj

if isinstance(subobj, MutableMapping) and \

self.pointer.contains(from_ptr):

raise JsonPatchConflict('Cannot move values into its own children')

obj = RemoveOperation({

'op': 'remove',

'path': self.operation['from']

}).apply(obj)

obj = AddOperation({

'op': 'add',

'path': self.location,

'value': value

}).apply(obj)

return obj

@property

def from_path(self):

from_ptr = JsonPointer(self.operation['from'])

return '/'.join(from_ptr.parts[:-1])

@property

def from_key(self):

from_ptr = JsonPointer(self.operation['from'])

try:

return int(from_ptr.parts[-1])

except TypeError:

return from_ptr.parts[-1]

@from_key.setter

def from_key(self, value):

from_ptr = JsonPointer(self.operation['from'])

from_ptr.parts[-1] = str(value)

self.operation['from'] = from_ptr.path

def _on_undo_remove(self, path, key):

if self.from_path == path:

if self.from_key >= key:

self.from_key += 1

else:

key -= 1

if self.path == path:

if self.key > key:

self.key += 1

else:

key += 1

return key

def _on_undo_add(self, path, key):

if self.from_path == path:

if self.from_key > key:

self.from_key -= 1

else:

key -= 1

if self.path == path:

if self.key > key:

self.key -= 1

else:

key += 1

return key

class TestOperation(PatchOperation):

"""Test value by specified location."""

def apply(self, obj):

try:

subobj, part = self.pointer.to_last(obj)

if part is None:

val = subobj

else:

val = self.pointer.walk(subobj, part)

except JsonPointerException as ex:

raise JsonPatchTestFailed(str(ex))

try:

value = self.operation['value']

except KeyError as ex:

raise InvalidJsonPatch(

"The operation does not contain a 'value' member")

if val != value:

msg = '{0} ({1}) is not equal to tested value {2} ({3})'

raise JsonPatchTestFailed(msg.format(val, type(val),

value, type(value)))

return obj

class CopyOperation(PatchOperation):

""" Copies an object property or an array element to a new location """

def apply(self, obj):

try:

from_ptr = JsonPointer(self.operation['from'])

except KeyError as ex:

raise InvalidJsonPatch(

"The operation does not contain a 'from' member")

subobj, part = from_ptr.to_last(obj)

try:

value = copy.deepcopy(subobj[part])

except (KeyError, IndexError) as ex:

raise JsonPatchConflict(str(ex))

obj = AddOperation({

'op': 'add',

'path': self.location,

'value': value

}).apply(obj)

return obj

class DiffBuilder(object):

def __init__(self, src, dst):

self.src = src

self.dst = dst

self.ops = []

self.index_changes = {}

def insert(self, op):

self.ops.append(op)

def execute(self):

self._compare_values('', None, self.src, self.dst)

return [op.operation for op in self.ops]

def _item_added(self, path, key, item, is_sequence):

if is_sequence:

key = self.get_index_change(path, key)

new_op = AddOperation({

'op': 'add',

'path': _path_join(path, key),

'value': item,

})

self.insert(new_op)

if is_sequence:

self.add_index_change(path, key, +1)

def _item_moved(self, path, key, item, newkey):

""" The `item` was moved from `key` to `newkey`

[a, b, c, d, e]

0 1, 2, 3, 4

case 1: move 1 to 3

[a, c, d, b, e]

0 1, 2, 3, 4

"""

key = self.get_index_change(path, key)

newkey = self.get_index_change(path, newkey)

if key == newkey:

return

new_op = MoveOperation({

'op': 'move',

'from': _path_join(path, key),

'path': _path_join(path, newkey),

})

self.insert(new_op)

self.add_index_change(path, key+1, -1)

self.add_index_change(path, newkey+1, +1)

def _item_removed(self, path, key, item, is_sequence):

if is_sequence:

key = self.get_index_change(path, key)

new_op = RemoveOperation({

'op': 'remove',

'path': _path_join(path, key),

})

self.insert(new_op)

if is_sequence:

self.add_index_change(path, key, -1)

def _item_replaced(self, path, key, item):

self.insert(ReplaceOperation({

'op': 'replace',

'path': _path_join(path, key),

'value': item,

}))

def _compare_dicts(self, path, src, dst):

src_keys = set(src.keys())

dst_keys = set(dst.keys())

added_keys = dst_keys - src_keys

removed_keys = src_keys - dst_keys

for key in removed_keys:

self._item_removed(path, str(key), src[key], False)

for key in added_keys:

self._item_added(path, str(key), dst[key], False)

for key in src_keys & dst_keys:

self._compare_values(path, key, src[key], dst[key])

def _compare_lists(self, path, src, dst):

len_src, len_dst = len(src), len(dst)

max_len = max(len_src, len_dst)

min_len = min(len_src, len_dst)

for key in range(max_len):

if key < min_len:

old, new = src[key], dst[key]

if old == new:

continue

elif isinstance(old, MutableMapping) and \

isinstance(new, MutableMapping):

self._compare_dicts(_path_join(path, key), old, new)

elif isinstance(old, MutableSequence) and \

isinstance(new, MutableSequence):

self._compare_lists(_path_join(path, key), old, new)

else:

self._item_removed(path, key, old, True)

self._item_added(path, key, new, True)

elif len_src > len_dst:

self._item_removed(path, len_dst, src[key], True)

else:

self._item_added(path, key, dst[key], True)

def _compare_values(self, path, key, src, dst):

if src == dst:

return

elif isinstance(src, MutableMapping) and \

isinstance(dst, MutableMapping):

self._compare_dicts(_path_join(path, key), src, dst)

elif isinstance(src, MutableSequence) and \

isinstance(dst, MutableSequence):

self._compare_lists(_path_join(path, key), src, dst)

else:

self._item_replaced(path, key, dst)

def add_index_change(self, path, key, change):

""" Store the index change of a certain path

[a, b, c]

0, 1, 2

When inserting d at position 1, the indexes of b and c change

[a, d, b, c]

0, 1, 2, 3

add_index_change('/', 1, +1)

"""

path_changes = self.index_changes.get(path, {})

key_change = path_changes.get(key, 0)

key_change = key_change + change

path_changes[key] = key_change

def get_index_change(self, path, key):

path_changes = self.index_changes.get(path, {})

return path_changes.get(key, 0) + key

def _path_join(path, key):

if key is None:

return path

return path + '/' + str(key).replace('~', '~0').replace('/', '~1')

python-json-patch/jsonpatch.py at hypothesis · vavanade/python-json-patch · GitHub

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