1  from fastapi import FastAPI, Request
 2  from fastapi.responses import JSONResponse
 3  import logging
 4  import traceback
 5  from .response_models import ErrorResponse
 6  
 7  logger = logging.getLogger("cerastes.api")
 8  
 9  class APIError(Exception):
10      """Custom exception for API errors"""
11      def __init__(self, message: str, status_code: int = 400, details: str = None):
12          self.message = message
13          self.status_code = status_code
14          self.details = details
15          super().__init__(self.message)
16  
17  def register_exception_handlers(app: FastAPI):
18      """Registers exception handlers for the FastAPI application"""
19      
20      @app.exception_handler(APIError)
21      async def handle_api_error(request: Request, exc: APIError):
22          """Handler for custom API errors"""
23          return JSONResponse(
24              status_code=exc.status_code,
25              content=ErrorResponse(
26                  error=exc.message,
27                  details=exc.details,
28                  status_code=exc.status_code
29              ).dict()
30          )
31  
32      @app.exception_handler(404)
33      async def handle_not_found(request: Request, exc: Exception):
34          """Handler for 404 errors"""
35          return JSONResponse(
36              status_code=404,
37              content=ErrorResponse(
38                  error="Resource not found", 
39                  status_code=404
40              ).dict()
41          )
42  
43      @app.exception_handler(405)
44      async def handle_method_not_allowed(request: Request, exc: Exception):
45          """Handler for 405 errors"""
46          return JSONResponse(
47              status_code=405,
48              content=ErrorResponse(
49                  error="Method not allowed", 
50                  status_code=405
51              ).dict()
52          )
53  
54      @app.exception_handler(500)
55      async def handle_server_error(request: Request, exc: Exception):
56          """Handler for server errors"""
57          logger.error(f"Server error: {str(exc)}")
58          logger.error(traceback.format_exc())
59          return JSONResponse(
60              status_code=500,
61              content=ErrorResponse(
62                  error="Internal server error", 
63                  status_code=500
64              ).dict()
65          )
66      
67      # FastAPI doesn't need an explicit handler for 400 like Flask
68      # as it automatically generates 422 error responses for validation errors