feat: Support for Pydantic field alias and serialization_alias (#583). …

…Closes #293

* (feat) Support for Pydantic field alias and serialization_alias

* (feat) Ensure null values are first in both types and items lists

* (feat) Add test case

* (feat) Allow empty strings as pydantic aliases

* (feat) Revert union re-ordering

dataclasses_avroschema/fields/base.py

@@ -120,8 +120,7 @@ def to_dict(self) -> dict:
         return dict(self.render())
 
     @abc.abstractmethod
-    def get_avro_type(self) -> typing.Any:
-        ...  # pragma: no cover
+    def get_avro_type(self) -> typing.Any: ...  # pragma: no cover
 
     def fake(self) -> typing.Any:
         return None

dataclasses_avroschema/pydantic/__init__.py

@@ -9,3 +9,6 @@
 mapper.LOGICAL_TYPES_FIELDS_CLASSES.update(PYDANTIC_LOGICAL_TYPES_FIELDS_CLASSES)  # type: ignore
 mapper.ALL_TYPES_FIELD_CLASSES.update(PYDANTIC_INMUTABLE_FIELDS_CLASSES)
 mapper.ALL_TYPES_FIELD_CLASSES.update(PYDANTIC_LOGICAL_TYPES_FIELDS_CLASSES)
+
+
+__all__ = ["AvroBaseModel"]

dataclasses_avroschema/pydantic/parser.py

@@ -18,6 +18,16 @@ def get_field_metadata(field_info: FieldInfo) -> dict[str, typing.Any]:
         )
         if field_info.description:
             metadata["doc"] = field_info.description  # type: ignore
+
+        aliases = set(metadata.get("aliases", []))
+
+        if field_info.alias is not None:
+            aliases.add(field_info.alias)
+        if field_info.serialization_alias is not None:
+            aliases.add(field_info.serialization_alias)
+        if aliases:
+            metadata["aliases"] = list(aliases)
+
         return metadata
 
     def parse_fields(self, exclude: typing.List) -> typing.List[Field]:

tests/schemas/pydantic/test_pydantic.py

@@ -91,6 +91,22 @@ class User(AvroBaseModel):
     assert User.avro_schema() == json.dumps(expected_schema)
 
 
+def test_pydantic_record_schema_with_aliases():
+    class User(AvroBaseModel):
+        foo: str = Field(alias="FOO")
+        bar: str = Field(serialization_alias="BAR")
+
+    expected_schema = {
+        "type": "record",
+        "name": "User",
+        "fields": [
+            {"aliases": ["FOO"], "name": "foo", "type": "string"},
+            {"aliases": ["BAR"], "name": "bar", "type": "string"},
+        ],
+    }
+    assert User.avro_schema() == json.dumps(expected_schema)
+
+
 def test_pydantic_record_schema_complex_types(user_advance_avro_json, color_enum):
     class UserAdvance(AvroBaseModel):
         name: str