Add support for Pydantic models with alias=

This change ensures that the generated JSON schema
/ OpenAPI docs match the `alias=` param when
present, and that any returned JSON uses the alias
for the keys. This is the most consistent behavior
with Pydantic's usage, *but* is a breaking change
for any existing code that uses `alias=` and
relies on FastOpenAPI returning the field name
instead of the alias.

We could put this behind a setting if desired
instead, i.e.,:

```
model_dump(
    by_alias=(True if use_aliases else False)
)
model_json_schema(
    mode=("serialization" if use_aliases else "validation")
)
```

Author: boydgreenfield

fastopenapi/base_router.py

@@ -225,7 +225,9 @@ def _build_parameters_and_body(
                 param.annotation, BaseModel
             ):
                 if http_method.upper() == "GET":
-                    model_schema = param.annotation.model_json_schema()
+                    model_schema = param.annotation.model_json_schema(
+                        mode="serialization"
+                    )
                     required_fields = model_schema.get("required", [])
                     properties = model_schema.get("properties", {})
                     for prop_name, prop_schema in properties.items():
@@ -337,7 +339,7 @@ def _serialize_response(result: Any) -> Any:
         from pydantic import BaseModel
 
         if isinstance(result, BaseModel):
-            return result.model_dump()
+            return result.model_dump(by_alias=True)
         if isinstance(result, list):
             return [BaseRouter._serialize_response(item) for item in result]
         if isinstance(result, dict):
@@ -356,7 +358,7 @@ def _get_model_schema(cls, model: type[BaseModel], definitions: dict) -> dict:
         if cache_key not in cls._model_schema_cache:
             # Generate the schema if it's not in the cache
             model_schema = model.model_json_schema(
-                ref_template="#/components/schemas/{model}"
+                mode="serialization", ref_template="#/components/schemas/{model}"
             )
 
             # Process and store nested definitions

tests/test_base_router.py

@@ -1,7 +1,7 @@
 from unittest.mock import MagicMock
 
 import pytest
-from pydantic import BaseModel
+from pydantic import BaseModel, computed_field
 
 # Import the class under test
 from fastopenapi.base_router import REDOC_URL, SWAGGER_URL, BaseRouter
@@ -13,6 +13,10 @@ class TestModel(BaseModel):
     age: int
     is_active: bool = True
 
+    @computed_field(alias="$active")
+    def aliased_is_active(self) -> bool:
+        return self.is_active
+
 
 class ResponseModel(BaseModel):
     id: int
@@ -30,7 +34,6 @@ class NestedListModel(BaseModel):
 
 
 class TestBaseRouter:
-
     def setup_method(self):
         self.app_mock = MagicMock()
 
@@ -465,6 +468,7 @@ def test_get_model_schema(self):
         assert "TestModel" in definitions
         assert definitions["TestModel"]["properties"]["name"]["type"] == "string"
         assert definitions["TestModel"]["properties"]["age"]["type"] == "integer"
+        assert definitions["TestModel"]["properties"]["$active"]["type"] == "boolean"
 
     def test_get_model_schema_with_nested_models(self):
         # Test getting schema for models with nested models
@@ -517,6 +521,7 @@ def endpoint(user: TestModel):
         assert result["user"].name == "John"
         assert result["user"].age == 30
         assert result["user"].is_active is True  # Default value
+        assert result["user"].aliased_is_active is True
 
     def test_resolve_endpoint_params_missing_required(self):
         # Test error when required parameter is missing
@@ -566,15 +571,17 @@ def endpoint(query: TestModel):
         )
 
         # Should convert model to query parameters
-        assert len(params) == 3
+        assert len(params) == 4
         assert params[0]["in"] == "query"
         assert params[1]["in"] == "query"
         assert params[2]["in"] == "query"
+        assert params[3]["in"] == "query"
 
         names = [p["name"] for p in params]
         assert "name" in names
         assert "age" in names
         assert "is_active" in names
+        assert "$active" in names  # alias
 
         # No request body for GET
         assert body is None