Merge pull request #906 from mwhudson/compact-serialization

add a more compact way of serializing objects

subiquity/common/serialize.py

@@ -27,7 +27,8 @@ import attr
 
 class Serializer:
 
-    def __init__(self):
+    def __init__(self, *, compact=False):
+        self.compact = compact
         self.typing_walkers = {
             typing.Union: self._walk_Union,
             list: self._walk_List,
@@ -76,6 +77,14 @@ class Serializer:
             }
 
     def _serialize_attr(self, annotation, value, metadata, path):
+        if self.compact:
+            r = []
+            for field in attr.fields(annotation):
+                r.append(self.serialize(
+                    field.type, getattr(value, field.name), field.metadata,
+                    f'{path}.{field.name}'))
+            return r
+        else:
             r = {}
             for field in attr.fields(annotation):
                 r.update(self._serialize_field(
@@ -115,6 +124,14 @@ class Serializer:
             }
 
     def _deserialize_attr(self, annotation, value, metadata, path):
+        if self.compact:
+            args = []
+            for field, v in zip(attr.fields(annotation), value):
+                args.append(self.deserialize(
+                    field.type, v, field.metadata,
+                    f'{path}.{field.name}'))
+            return annotation(*args)
+        else:
             args = {}
             for field in attr.fields(annotation):
                 args.update(self._deserialize_field(

subiquity/common/tests/test_serialization.py

@@ -0,0 +1,136 @@
+# Copyright 2021 Canonical, Ltd.
+#
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU Affero General Public License as
+# published by the Free Software Foundation, either version 3 of the
+# License, or (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU Affero General Public License for more details.
+#
+# You should have received a copy of the GNU Affero General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+import attr
+import random
+import string
+import typing
+import unittest
+
+from subiquity.common.serialize import Serializer
+
+
+@attr.s(auto_attribs=True)
+class Data:
+    field1: str
+    field2: int
+
+    @staticmethod
+    def make_random():
+        return Data(
+            random.choice(string.ascii_letters),
+            random.randint(0, 1000))
+
+
+@attr.s(auto_attribs=True)
+class Container:
+    data: Data
+    data_list: typing.List[Data]
+
+    @staticmethod
+    def make_random():
+        return Container(
+            data=Data.make_random(),
+            data_list=[Data.make_random()
+                       for i in range(random.randint(10, 20))])
+
+
+class CommonSerializerTests:
+
+    simple_examples = [
+        (int, 1),
+        (str, "v"),
+        (list, [1]),
+        (dict, {2: 3}),
+        (type(None), None),
+        ]
+
+    def assertSerializesTo(self, annotation, value, expected):
+        self.assertEqual(
+            self.serializer.serialize(annotation, value), expected)
+
+    def assertDeserializesTo(self, annotation, value, expected):
+        self.assertEqual(
+            self.serializer.deserialize(annotation, value), expected)
+
+    def assertRoundtrips(self, annotation, value):
+        serialized = self.serializer.serialize(annotation, value)
+        self.assertDeserializesTo(annotation, serialized, value)
+
+    def assertSerialization(self, annotation, value, expected):
+        self.assertSerializesTo(annotation, value, expected)
+        self.assertDeserializesTo(annotation, expected, value)
+
+    def test_roundtrip_scalars(self):
+        for typ, val in self.simple_examples:
+            self.assertRoundtrips(typ, val)
+
+    def test_roundtrip_optional(self):
+        self.assertRoundtrips(typing.Optional[int], None)
+        self.assertRoundtrips(typing.Optional[int], 1)
+
+    def test_roundtrip_list(self):
+        self.assertRoundtrips(typing.List[str], ["a"])
+        self.assertRoundtrips(typing.List[int], [23])
+
+    def test_roundtrip_attr(self):
+        self.assertRoundtrips(Data, Data.make_random())
+        self.assertRoundtrips(Container, Container.make_random())
+
+    def test_scalars(self):
+        for typ, val in self.simple_examples:
+            self.assertSerialization(typ, val, val)
+
+
+class TestSerializer(CommonSerializerTests, unittest.TestCase):
+
+    serializer = Serializer()
+
+    def test_serialize_attr(self):
+        data = Data.make_random()
+        expected = {'field1': data.field1, 'field2': data.field2}
+        self.assertSerialization(Data, data, expected)
+
+    def test_serialize_container(self):
+        data1 = Data.make_random()
+        data2 = Data.make_random()
+        container = Container(data1, [data2])
+        expected = {
+            'data': {'field1': data1.field1, 'field2': data1.field2},
+            'data_list': [
+                {'field1': data2.field1, 'field2': data2.field2},
+                ],
+            }
+        self.assertSerialization(Container, container, expected)
+
+
+class TestCompactSerializer(CommonSerializerTests, unittest.TestCase):
+
+    serializer = Serializer(compact=True)
+
+    def test_serialize_attr(self):
+        data = Data.make_random()
+        expected = [data.field1, data.field2]
+        self.assertSerialization(Data, data, expected)
+
+    def test_serialize_container(self):
+        data1 = Data.make_random()
+        data2 = Data.make_random()
+        container = Container(data1, [data2])
+        expected = [
+            [data1.field1, data1.field2],
+            [[data2.field1, data2.field2]],
+            ]
+        self.assertSerialization(Container, container, expected)