Add custom JSON response configuration and implementation

configuration/config.json

@@ -17,5 +17,11 @@
     "ssl_keyfile": "key.pem",
     "ssl_certfile": "cert.pem",
     "days_valid": 365
+  },
+  "json_response": {
+    "ensure_ascii": false,
+    "allow_nan": false,
+    "indent": null,
+    "media_type": "application/json; charset=utf-8"
   }
 }

python_template_server/models.py

@@ -1,9 +1,12 @@
 """Pydantic models for the server."""
 
+import json
 from datetime import datetime
 from enum import IntEnum, StrEnum, auto
 from pathlib import Path
+from typing import Any
 
+from fastapi.responses import JSONResponse
 from pydantic import BaseModel, Field
 
 
@@ -61,13 +64,23 @@ def ssl_cert_file_path(self) -> Path:
         return Path(self.directory) / self.ssl_certfile
 
 
+class JSONResponseConfigModel(BaseModel):
+    """JSON response rendering configuration model."""
+
+    ensure_ascii: bool = Field(default=False, description="Whether to escape non-ASCII characters")
+    allow_nan: bool = Field(default=False, description="Whether to allow NaN values in JSON")
+    indent: int | None = Field(default=None, description="Indentation level for pretty-printing (None for compact)")
+    media_type: str = Field(default="application/json; charset=utf-8", description="Media type for JSON responses")
+
+
 class TemplateServerConfig(BaseModel):
     """Template server configuration."""
 
     server: ServerConfigModel = Field(default_factory=ServerConfigModel)
     security: SecurityConfigModel = Field(default_factory=SecurityConfigModel)
     rate_limit: RateLimitConfigModel = Field(default_factory=RateLimitConfigModel)
     certificate: CertificateConfigModel = Field(default_factory=CertificateConfigModel)
+    json_response: JSONResponseConfigModel = Field(default_factory=JSONResponseConfigModel)
 
     def save_to_file(self, filepath: Path) -> None:
         """Save the configuration to a JSON file.
@@ -79,6 +92,32 @@ def save_to_file(self, filepath: Path) -> None:
 
 
 # API Response Models
+class CustomJSONResponse(JSONResponse):
+    """Custom JSONResponse with configurable rendering options."""
+
+    _ensure_ascii: bool = False
+    _allow_nan: bool = False
+    _indent: int | None = None
+
+    @classmethod
+    def configure(cls, json_response_config: JSONResponseConfigModel) -> None:
+        """Configure class-level JSON rendering options."""
+        cls._ensure_ascii = json_response_config.ensure_ascii
+        cls._allow_nan = json_response_config.allow_nan
+        cls._indent = json_response_config.indent
+        cls.media_type = json_response_config.media_type
+
+    def render(self, content: Any) -> bytes:  # noqa: ANN401
+        """Render content to JSON with configured options."""
+        return json.dumps(
+            content,
+            ensure_ascii=self._ensure_ascii,
+            allow_nan=self._allow_nan,
+            indent=self._indent,
+            separators=(",", ":"),
+        ).encode("utf-8")
+
+
 class ResponseCode(IntEnum):
     """HTTP response codes for API endpoints."""
 

python_template_server/template_server.py

@@ -12,7 +12,6 @@
 
 import uvicorn
 from fastapi import FastAPI, HTTPException, Request, Security
-from fastapi.responses import JSONResponse
 from fastapi.security import APIKeyHeader
 from prometheus_client import Counter, Gauge
 from prometheus_fastapi_instrumentator import Instrumentator
@@ -26,7 +25,13 @@
 from python_template_server.constants import API_KEY_HEADER_NAME, API_PREFIX, CONFIG_FILE_PATH, PACKAGE_NAME
 from python_template_server.logging_setup import setup_logging
 from python_template_server.middleware import RequestLoggingMiddleware, SecurityHeadersMiddleware
-from python_template_server.models import GetHealthResponse, ResponseCode, ServerHealthStatus, TemplateServerConfig
+from python_template_server.models import (
+    CustomJSONResponse,
+    GetHealthResponse,
+    ResponseCode,
+    ServerHealthStatus,
+    TemplateServerConfig,
+)
 
 setup_logging()
 logger = logging.getLogger(__name__)
@@ -63,13 +68,16 @@ def __init__(
         self.config_filepath = config_filepath
         self.config = config or self.load_config(config_filepath)
 
+        CustomJSONResponse.configure(self.config.json_response)
+
         self.package_metadata = metadata(self.package_name)
         self.app = FastAPI(
             title=self.package_metadata["Name"],
             description=self.package_metadata["Summary"],
             version=self.package_metadata["Version"],
             root_path=self.api_prefix,
             lifespan=self.lifespan,
+            default_response_class=CustomJSONResponse,
         )
         self.api_key_header = APIKeyHeader(name=self.api_key_header_name, auto_error=False)
 
@@ -177,7 +185,7 @@ def _setup_security_headers(self) -> None:
             self.config.security.content_security_policy,
         )
 
-    async def _rate_limit_exception_handler(self, request: Request, exc: RateLimitExceeded) -> JSONResponse:
+    async def _rate_limit_exception_handler(self, request: Request, exc: RateLimitExceeded) -> CustomJSONResponse:
         """Handle rate limit exceeded exceptions and track metrics.
 
         :param Request request: The incoming HTTP request
@@ -187,7 +195,7 @@ async def _rate_limit_exception_handler(self, request: Request, exc: RateLimitEx
         self.rate_limit_exceeded_counter.labels(endpoint=request.url.path).inc()
 
         # Return JSON response with 429 status
-        return JSONResponse(
+        return CustomJSONResponse(
             status_code=429,
             content={"detail": "Rate limit exceeded"},
             headers={"Retry-After": str(exc.retry_after)} if hasattr(exc, "retry_after") else {},

tests/conftest.py

@@ -8,6 +8,7 @@
 
 from python_template_server.models import (
     CertificateConfigModel,
+    JSONResponseConfigModel,
     RateLimitConfigModel,
     SecurityConfigModel,
     ServerConfigModel,
@@ -125,28 +126,45 @@ def mock_certificate_config_dict() -> dict:
     }
 
 
+@pytest.fixture
+def mock_json_response_config_dict() -> dict:
+    """Provide a mock JSON response configuration dictionary."""
+    return {
+        "ensure_ascii": False,
+        "allow_nan": False,
+        "indent": None,
+        "media_type": "application/json; charset=utf-8",
+    }
+
+
 @pytest.fixture
 def mock_server_config(mock_server_config_dict: dict) -> ServerConfigModel:
     """Provide a mock ServerConfigModel instance."""
-    return ServerConfigModel(**mock_server_config_dict)
+    return ServerConfigModel.model_validate(mock_server_config_dict)
 
 
 @pytest.fixture
 def mock_security_config(mock_security_config_dict: dict) -> SecurityConfigModel:
     """Provide a mock SecurityConfigModel instance."""
-    return SecurityConfigModel(**mock_security_config_dict)
+    return SecurityConfigModel.model_validate(mock_security_config_dict)
 
 
 @pytest.fixture
 def mock_rate_limit_config(mock_rate_limit_config_dict: dict) -> RateLimitConfigModel:
     """Provide a mock RateLimitConfigModel instance."""
-    return RateLimitConfigModel(**mock_rate_limit_config_dict)
+    return RateLimitConfigModel.model_validate(mock_rate_limit_config_dict)
 
 
 @pytest.fixture
 def mock_certificate_config(mock_certificate_config_dict: dict) -> CertificateConfigModel:
     """Provide a mock CertificateConfigModel instance."""
-    return CertificateConfigModel(**mock_certificate_config_dict)
+    return CertificateConfigModel.model_validate(mock_certificate_config_dict)
+
+
+@pytest.fixture
+def mock_json_response_config(mock_json_response_config_dict: dict) -> JSONResponseConfigModel:
+    """Provide a mock JSONResponseConfigModel instance."""
+    return JSONResponseConfigModel.model_validate(mock_json_response_config_dict)
 
 
 @pytest.fixture
@@ -155,11 +173,13 @@ def mock_template_server_config(
     mock_security_config: SecurityConfigModel,
     mock_rate_limit_config: RateLimitConfigModel,
     mock_certificate_config: CertificateConfigModel,
+    mock_json_response_config: JSONResponseConfigModel,
 ) -> TemplateServerConfig:
     """Provide a mock TemplateServerConfig instance."""
     return TemplateServerConfig(
         server=mock_server_config,
         security=mock_security_config,
         rate_limit=mock_rate_limit_config,
         certificate=mock_certificate_config,
+        json_response=mock_json_response_config,
     )

tests/test_models.py

@@ -8,7 +8,9 @@
 from python_template_server.models import (
     BaseResponse,
     CertificateConfigModel,
+    CustomJSONResponse,
     GetHealthResponse,
+    JSONResponseConfigModel,
     RateLimitConfigModel,
     ResponseCode,
     SecurityConfigModel,
@@ -87,6 +89,16 @@ def test_days_valid_field(
             CertificateConfigModel(**invalid_config_data)
 
 
+class TestJSONResponseConfigModel:
+    """Unit tests for the JSONResponseConfigModel class."""
+
+    def test_model_dump(
+        self, mock_json_response_config_dict: dict, mock_json_response_config: JSONResponseConfigModel
+    ) -> None:
+        """Test the model_dump method."""
+        assert mock_json_response_config.model_dump() == mock_json_response_config_dict
+
+
 class TestTemplateServerConfig:
     """Unit tests for the TemplateServerConfig class."""
 
@@ -97,13 +109,15 @@ def test_model_dump(
         mock_security_config_dict: dict,
         mock_rate_limit_config_dict: dict,
         mock_certificate_config_dict: dict,
+        mock_json_response_config_dict: dict,
     ) -> None:
         """Test the model_dump method."""
         expected_dict = {
             "server": mock_server_config_dict,
             "security": mock_security_config_dict,
             "rate_limit": mock_rate_limit_config_dict,
             "certificate": mock_certificate_config_dict,
+            "json_response": mock_json_response_config_dict,
         }
         assert mock_template_server_config.model_dump() == expected_dict
 
@@ -119,6 +133,59 @@ def test_save_to_file(
 
 
 # API Response Models
+class TestCustomJSONResponse:
+    """Unit tests for the CustomJSONResponse class."""
+
+    def test_configure_method(self, mock_json_response_config: JSONResponseConfigModel) -> None:
+        """Test the configure class method."""
+        CustomJSONResponse.configure(mock_json_response_config)
+
+        assert CustomJSONResponse._ensure_ascii == mock_json_response_config.ensure_ascii
+        assert CustomJSONResponse._allow_nan == mock_json_response_config.allow_nan
+        assert CustomJSONResponse._indent == mock_json_response_config.indent
+        assert CustomJSONResponse.media_type == mock_json_response_config.media_type
+
+    def test_render_with_unicode(self, mock_json_response_config: JSONResponseConfigModel) -> None:
+        """Test rendering JSON with Unicode characters (emojis)."""
+        CustomJSONResponse.configure(mock_json_response_config)
+        response = CustomJSONResponse(content={"message": "Hello 👋 World 🌍"})
+
+        rendered = response.render({"message": "Hello 👋 World 🌍"})
+        assert b"Hello \\ud83d\\udc4b World" not in rendered  # Should NOT be escaped
+        assert "👋".encode() in rendered  # Should preserve emoji
+        assert "🌍".encode() in rendered
+
+    def test_render_with_ensure_ascii_true(self) -> None:
+        """Test rendering with ensure_ascii=True."""
+        config = JSONResponseConfigModel(ensure_ascii=True)
+        CustomJSONResponse.configure(config)
+        response = CustomJSONResponse(content={"message": "Hello 👋"})
+
+        rendered = response.render({"message": "Hello 👋"})
+        # With ensure_ascii=True, Unicode should be escaped
+        assert b"\\ud83d\\udc4b" in rendered or b"\\u" in rendered
+
+    def test_render_with_indent(self) -> None:
+        """Test rendering with indentation."""
+        config = JSONResponseConfigModel(indent=2)
+        CustomJSONResponse.configure(config)
+        response = CustomJSONResponse(content={"key": "value"})
+
+        rendered = response.render({"key": "value"})
+        # With indent, output should have newlines and spaces
+        assert b"\n" in rendered
+        assert b"  " in rendered
+
+    def test_render_compact(self, mock_json_response_config: JSONResponseConfigModel) -> None:
+        """Test rendering in compact mode (no indent)."""
+        CustomJSONResponse.configure(mock_json_response_config)
+        response = CustomJSONResponse(content={"key": "value", "number": 42})
+
+        rendered = response.render({"key": "value", "number": 42})
+        # Compact mode should use "," separator without spaces after
+        assert rendered == b'{"key":"value","number":42}'
+
+
 class TestResponseCode:
     """Unit tests for the ResponseCode enum."""
 

tests/test_template_server.py

@@ -22,6 +22,7 @@
 from python_template_server.middleware import RequestLoggingMiddleware, SecurityHeadersMiddleware
 from python_template_server.models import (
     BaseResponse,
+    CustomJSONResponse,
     ResponseCode,
     ServerHealthStatus,
     TemplateServerConfig,
@@ -124,6 +125,24 @@ def test_request_middleware_added(self, mock_template_server: TemplateServer) ->
         assert RequestLoggingMiddleware in middlewares
         assert SecurityHeadersMiddleware in middlewares
 
+    def test_json_response_configured(
+        self, mock_template_server: TemplateServer, mock_template_server_config: TemplateServerConfig
+    ) -> None:
+        """Test that CustomJSONResponse is properly configured during initialization."""
+        # Verify CustomJSONResponse class variables are set correctly
+        assert CustomJSONResponse._ensure_ascii == mock_template_server_config.json_response.ensure_ascii
+        assert CustomJSONResponse._allow_nan == mock_template_server_config.json_response.allow_nan
+        assert CustomJSONResponse._indent == mock_template_server_config.json_response.indent
+        assert CustomJSONResponse.media_type == mock_template_server_config.json_response.media_type
+
+        # Test that CustomJSONResponse renders correctly with configured settings
+        response = CustomJSONResponse(content={"test": "data", "emoji": "👋"})
+        rendered = response.render({"test": "data", "emoji": "👋"})
+
+        # With ensure_ascii=False, emojis should be preserved
+        assert "👋".encode() in rendered
+        assert b'"test":"data"' in rendered  # Compact format (no spaces)
+
 
 class TestLoadConfig:
     """Tests for the load_config function."""