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

Add docstrings and fix code style in favour to pylint.

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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
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55
jsonpatch.py
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@@ -30,7 +30,8 @@
# THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. # 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 # Will be parsed by setup.py to determine package metadata
__author__ = 'Stefan Kögl <stefan@skoegl.net>' __author__ = 'Stefan Kögl <stefan@skoegl.net>'
@@ -43,11 +44,16 @@ import json
class JsonPatchException(Exception): class JsonPatchException(Exception):
pass """Base Json Patch exception"""
class JsonPatchConflict(JsonPatchException): 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): def apply_patch(doc, patch):
@@ -61,8 +67,8 @@ def apply_patch(doc, patch):
{'foo': 'bar', 'baz': 'qux'} {'foo': 'bar', 'baz': 'qux'}
""" """
p = JsonPatch(patch) patch = JsonPatch(patch)
return p.apply(doc) return patch.apply(doc)
class JsonPatch(object): class JsonPatch(object):
@@ -84,7 +90,7 @@ class JsonPatch(object):
def __init__(self, patch): def __init__(self, patch):
self.patch = patch self.patch = patch
self.OPERATIONS = { self.operations = {
'remove': RemoveOperation, 'remove': RemoveOperation,
'add': AddOperation, 'add': AddOperation,
'replace': ReplaceOperation, 'replace': ReplaceOperation,
@@ -92,34 +98,30 @@ class JsonPatch(object):
'test': TestOperation 'test': TestOperation
} }
@classmethod @classmethod
def from_string(cls, patch_str): def from_string(cls, patch_str):
"""Creates JsonPatch instance from string source."""
patch = json.loads(patch_str) patch = json.loads(patch_str)
return cls(patch) return cls(patch)
def apply(self, obj): def apply(self, obj):
""" Applies the patch to given object """ """Applies the patch to given object."""
for operation in self.patch: for operation in self.patch:
op = self._get_operation(operation) operation = self._get_operation(operation)
op.apply(obj) operation.apply(obj)
return obj return obj
def _get_operation(self, operation): 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: if action in operation:
location = operation[action] location = operation[action]
op = op_cls(location, operation) return op_cls(location, operation)
return op
raise JsonPatchException("invalid operation '%s'" % operation) raise JsonPatchException("invalid operation '%s'" % operation)
class PatchOperation(object): class PatchOperation(object):
"""A single operation inside a JSON Patch.""" """A single operation inside a JSON Patch."""
@@ -127,25 +129,27 @@ class PatchOperation(object):
self.location = location self.location = location
self.operation = operation 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): 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('/') parts = location.split('/')
if parts.pop(0) != '': if parts.pop(0) != '':
raise JsonPatchException('location must starts with /') raise JsonPatchException('location must starts with /')
for part in parts[:-1]: 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) _, last_loc = self._step(obj, parts[-1], must_exist=last_must_exist)
return obj, last_loc return obj, last_loc
def _step(self, obj, loc_part, must_exist=True): 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): if isinstance(obj, dict):
part_variants = [loc_part] part_variants = [loc_part]
@@ -196,7 +200,8 @@ class AddOperation(PatchOperation):
subobj[part] = value subobj[part] = value
else: 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): class ReplaceOperation(PatchOperation):
@@ -212,10 +217,12 @@ class ReplaceOperation(PatchOperation):
elif isinstance(subobj, dict): elif isinstance(subobj, dict):
if not part in subobj: 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: 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 subobj[part] = value