openstack/deb-python-json-patch
Code Issues Proposed changes

Add docstrings and fix code style in favour to pylint.

Browse Source
This commit is contained in:
Alexander Shorin
2011-12-25 20:13:37 +04:00
parent 477a1996a5
commit a1729beaa1
1 changed files with 39 additions and 32 deletions
Download Patch File Download Diff File Expand all files Collapse all files

71
jsonpatch.py
View File

@@ -30,7 +30,8 @@
# 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"""
"""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>'
@@ -43,15 +44,20 @@ import json
class JsonPatchException(Exception):
pass
"""Base Json Patch exception"""
class JsonPatchConflict(JsonPatchException):
pass
"""Raises if patch could be applied due to conflict situations 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.
"""
def apply_patch(doc, patch):
""" Apply list of patches to specified json document.
"""Apply list of patches to specified json document.
>>> doc = {'foo': 'bar'}
>>> other = apply_patch(doc, [{'add': '/baz', 'value': 'qux'}])
@@ -61,12 +67,12 @@ def apply_patch(doc, patch):
{'foo': 'bar', 'baz': 'qux'}
"""
p = JsonPatch(patch)
return p.apply(doc)
patch = JsonPatch(patch)
return patch.apply(doc)
class JsonPatch(object):
""" A JSON Patch is a list of Patch Operations.
"""A JSON Patch is a list of Patch Operations.
>>> patch = JsonPatch([
... {'add': '/foo', 'value': 'bar'},
@@ -84,7 +90,7 @@ class JsonPatch(object):
def __init__(self, patch):
self.patch = patch
self.OPERATIONS = {
self.operations = {
'remove': RemoveOperation,
'add': AddOperation,
'replace': ReplaceOperation,
@@ -92,60 +98,58 @@ class JsonPatch(object):
'test': TestOperation
}
@classmethod
def from_string(cls, patch_str):
"""Creates JsonPatch instance from string source."""
patch = json.loads(patch_str)
return cls(patch)
def apply(self, obj):
""" Applies the patch to given object """
"""Applies the patch to given object."""
for operation in self.patch:
op = self._get_operation(operation)
op.apply(obj)
operation = self._get_operation(operation)
operation.apply(obj)
return obj
def _get_operation(self, operation):
for action, op_cls in self.OPERATIONS.items():
for action, op_cls in self.operations.items():
if action in operation:
location = operation[action]
op = op_cls(location, operation)
return op
return op_cls(location, operation)
raise JsonPatchException("invalid operation '%s'" % operation)
class PatchOperation(object):
""" A single operation inside a JSON Patch. """
"""A single operation inside a JSON Patch."""
def __init__(self, location, operation):
self.location = location
self.operation = operation
def apply(self, obj):
"""Abstract method that applies patch operation to specified object."""
raise NotImplementedError('should implement patch operation.')
def locate(self, obj, location, last_must_exist=True):
""" Walks through the object according to location
"""Walks through the object according to location.
Returns the last step as (sub-object, last location-step) """
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)
obj, _ = 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 """
"""Goes one step in a locate() call."""
if isinstance(obj, dict):
part_variants = [loc_part]
@@ -169,7 +173,7 @@ class PatchOperation(object):
class RemoveOperation(PatchOperation):
""" Removes an object property or an array element. """
"""Removes an object property or an array element."""
def apply(self, obj):
subobj, part = self.locate(obj, self.location)
@@ -177,7 +181,7 @@ class RemoveOperation(PatchOperation):
class AddOperation(PatchOperation):
""" Adds an object property or an array element. """
"""Adds an object property or an array element."""
def apply(self, obj):
value = self.operation["value"]
@@ -196,11 +200,12 @@ class AddOperation(PatchOperation):
subobj[part] = value
else:
raise JsonPatchConflict("can't add to type '%s'" % subobj.__class__.__name__)
raise JsonPatchConflict("can't add to type '%s'"
"" % subobj.__class__.__name__)
class ReplaceOperation(PatchOperation):
""" Replaces an object property or an array element by new value. """
"""Replaces an object property or an array element by new value."""
def apply(self, obj):
value = self.operation["value"]
@@ -212,16 +217,18 @@ class ReplaceOperation(PatchOperation):
elif isinstance(subobj, dict):
if not part in subobj:
raise JsonPatchConflict("can't replace non-existant object '%s'" % part)
raise JsonPatchConflict("can't replace non-existant object '%s'"
"" % part)
else:
raise JsonPatchConflict("can't replace in type '%s'" % subobj.__class__.__name__)
raise JsonPatchConflict("can't replace in type '%s'"
"" % subobj.__class__.__name__)
subobj[part] = value
class MoveOperation(PatchOperation):
""" Moves an object property or an array element to new location. """
"""Moves an object property or an array element to new location."""
def apply(self, obj):
subobj, part = self.locate(obj, self.location)
@@ -231,7 +238,7 @@ class MoveOperation(PatchOperation):
class TestOperation(PatchOperation):
""" Test value by specified location. """
"""Test value by specified location."""
def apply(self, obj):
value = self.operation['value']