From 0167d345ee9d7ef0f74b947ec3a7ea94def178be Mon Sep 17 00:00:00 2001 From: Christian Lyder Jacobsen Date: Fri, 6 Mar 2020 11:41:38 +0100 Subject: Subclassing can override json dumper and loader Additionally: * from_string gets a loads parameter * to_string gets a dumps_parameter * documentation added * added more tests --- doc/tutorial.rst | 52 +++++++++++++++++++++++++++++++++++++++++++++++++ jsonpatch.py | 22 ++++++++++++++------- tests.py | 59 ++++++++++++++++++++++++++++++++++++++++++++++++-------- 3 files changed, 118 insertions(+), 15 deletions(-) diff --git a/doc/tutorial.rst b/doc/tutorial.rst index 538cd0e..0bb1a9c 100644 --- a/doc/tutorial.rst +++ b/doc/tutorial.rst @@ -67,3 +67,55 @@ explicitly. # or from a list >>> patch = [{'op': 'add', 'path': '/baz', 'value': 'qux'}] >>> res = jsonpatch.apply_patch(obj, patch) + + +Dealing with Custom Types +------------------------- + +Custom JSON dump and load functions can be used to support custom types such as +`decimal.Decimal`. The following examples shows how the +`simplejson `_ package, which has native +support for Python's ``Decimal`` type, can be used to create a custom +``JsonPatch`` subclass with ``Decimal`` support: + +.. code-block:: python + + >>> import decimal + >>> import simplejson + + >>> class DecimalJsonPatch(jsonpatch.JsonPatch): + @staticmethod + def json_dumper(obj): + return simplejson.dumps(obj) + + @staticmethod + def json_loader(obj): + return simplejson.loads(obj, use_decimal=True, + object_pairs_hook=jsonpatch.multidict) + + >>> src = {} + >>> dst = {'bar': decimal.Decimal('1.10')} + >>> patch = DecimalJsonPatch.from_diff(src, dst) + >>> doc = {'foo': 1} + >>> result = patch.apply(doc) + {'foo': 1, 'bar': Decimal('1.10')} + +Instead of subclassing it is also possible to pass a dump function to +``from_diff``: + + >>> patch = jsonpatch.JsonPatch.from_diff(src, dst, dumps=simplejson.dumps) + +a dumps function to ``to_string``: + + >>> serialized_patch = patch.to_string(dumps=simplejson.dumps) + '[{"op": "add", "path": "/bar", "value": 1.10}]' + +and load function to ``from_string``: + + >>> import functools + >>> loads = functools.partial(simplejson.loads, use_decimal=True, + object_pairs_hook=jsonpatch.multidict) + >>> patch.from_string(serialized_patch, loads=loads) + >>> doc = {'foo': 1} + >>> result = patch.apply(doc) + {'foo': 1, 'bar': Decimal('1.10')} diff --git a/jsonpatch.py b/jsonpatch.py index ebaa8e3..ce8a89f 100644 --- a/jsonpatch.py +++ b/jsonpatch.py @@ -165,6 +165,9 @@ def make_patch(src, dst): class JsonPatch(object): + json_dumper = staticmethod(json.dumps) + json_loader = staticmethod(_jsonloads) + """A JSON Patch is a list of Patch Operations. >>> patch = JsonPatch([ @@ -246,19 +249,23 @@ class JsonPatch(object): return not(self == other) @classmethod - def from_string(cls, patch_str): + def from_string(cls, patch_str, loads=None): """Creates JsonPatch instance from string source. :param patch_str: JSON patch as raw string. :type patch_str: str + :param loads: A function of one argument that loads a serialized + JSON string. + :type loads: function :return: :class:`JsonPatch` instance. """ - patch = _jsonloads(patch_str) + json_loader = loads or cls.json_loader + patch = json_loader(patch_str) return cls(patch) @classmethod - def from_diff(cls, src, dst, optimization=True, dumps=json.dumps): + def from_diff(cls, src, dst, optimization=True, dumps=None): """Creates JsonPatch instance based on comparing of two document objects. Json patch would be created for `src` argument against `dst` one. @@ -282,15 +289,16 @@ class JsonPatch(object): >>> new == dst True """ - - builder = DiffBuilder(dumps) + json_dumper = dumps or cls.json_dumper + builder = DiffBuilder(json_dumper) builder._compare_values('', None, src, dst) ops = list(builder.execute()) return cls(ops) - def to_string(self): + def to_string(self, dumps=None): """Returns patch set as JSON string.""" - return json.dumps(self.patch) + json_dumper = dumps or self.json_dumper + return json_dumper(self.patch) @property def _ops(self): diff --git a/tests.py b/tests.py index 8837bfa..a843b35 100755 --- a/tests.py +++ b/tests.py @@ -268,6 +268,34 @@ class EqualityTestCase(unittest.TestCase): self.assertEqual(json.dumps(patch_obj), patch.to_string()) +def custom_types_dumps(obj): + def default(obj): + if isinstance(obj, decimal.Decimal): + return {'__decimal__': str(obj)} + raise TypeError('Unknown type') + + return json.dumps(obj, default=default) + + +def custom_types_loads(obj): + def as_decimal(dct): + if '__decimal__' in dct: + return decimal.Decimal(dct['__decimal__']) + return dct + + return json.loads(obj, object_hook=as_decimal) + + +class CustomTypesJsonPatch(jsonpatch.JsonPatch): + @staticmethod + def json_dumper(obj): + return custom_types_dumps(obj) + + @staticmethod + def json_loader(obj): + return custom_types_loads(obj) + + class MakePatchTestCase(unittest.TestCase): def test_apply_patch_to_copy(self): @@ -446,18 +474,33 @@ class MakePatchTestCase(unittest.TestCase): self.assertEqual(res, dst) self.assertIsInstance(res['A'], float) - def test_custom_types(self): - def default(obj): - if isinstance(obj, decimal.Decimal): - return str(obj) - raise TypeError('Unknown type') + def test_custom_types_diff(self): + old = {'value': decimal.Decimal('1.0')} + new = {'value': decimal.Decimal('1.00')} + generated_patch = jsonpatch.JsonPatch.from_diff( + old, new, dumps=custom_types_dumps) + str_patch = generated_patch.to_string(dumps=custom_types_dumps) + loaded_patch = jsonpatch.JsonPatch.from_string( + str_patch, loads=custom_types_loads) + self.assertEqual(generated_patch, loaded_patch) + new_from_patch = jsonpatch.apply_patch(old, generated_patch) + self.assertEqual(new, new_from_patch) - def dumps(obj): - return json.dumps(obj, default=default) + def test_custom_types_subclass(self): + old = {'value': decimal.Decimal('1.0')} + new = {'value': decimal.Decimal('1.00')} + generated_patch = CustomTypesJsonPatch.from_diff(old, new) + str_patch = generated_patch.to_string() + loaded_patch = CustomTypesJsonPatch.from_string(str_patch) + self.assertEqual(generated_patch, loaded_patch) + new_from_patch = jsonpatch.apply_patch(old, loaded_patch) + self.assertEqual(new, new_from_patch) + def test_custom_types_subclass_load(self): old = {'value': decimal.Decimal('1.0')} new = {'value': decimal.Decimal('1.00')} - patch = jsonpatch.JsonPatch.from_diff(old, new, dumps=dumps) + patch = CustomTypesJsonPatch.from_string( + '[{"op": "replace", "path": "/value", "value": {"__decimal__": "1.00"}}]') new_from_patch = jsonpatch.apply_patch(old, patch) self.assertEqual(new, new_from_patch) -- cgit v1.2.1