Django REST Exceptions

Question

I currently have some code for a view based on the Django REST Framework. Ive been using a customer exception class, but ideally I want to use the inbuilt Django REST exceptions.

From the code below I feel this probably not the best or cleanest way to utilize the REST Framework exceptions to its maximum.

Has anyone got any good examples where they are catching issues and returning them cleanly with the REST built in exceptions ?

class JSONResponse(HttpResponse):
    def __init__(self, data, **kwargs):
       content = JSONRenderer().render(data)
       kwargs['content_type'] = 'application/json'
       super(JSONResponse, self).__init__(content, **kwargs)

def queryInput(request):
    try:
        auth_token = session_id = getAuthHeader(request)
        if not auth_token:
            return JSONResponse({'detail' : "fail", "error" : "No X-Auth-Token Found", "data" : None}, status=500)

        if request.method:
            data = JSONParser().parse(request)
            serializer = queryInputSerializer(data=data)

        if request.method == 'POST':
            if serializer.is_valid():
                input= serializer.data["input"]
                fetchData = MainRunner(input=input,auth_token=auth_token)
                main_data = fetchData.main()

            if main_data:
                return JSONResponse({'detail' : "success", "error" : None, "data" : main_data}, status=201)

        return JSONResponse({'detail' : "Unknown Error","error" : True, "data" : None}, status=500)

    except Exception as e:
           return JSONResponse({'error' : str(e)},status=500)

emptyflash · Accepted Answer · 2017-10-12 20:12:31Z

89

+50

The Django REST framework provides several built in exceptions, which are mostly subclasses of DRF's APIException.

You can raise exceptions in your view like you normally would in Python:

from rest_framework.exceptions import APIException

def my_view(request):
    raise APIException("There was a problem!")

You could also create your own custom exception by inheriting from APIException and setting status_code and default_detail. Some of the built in ones are: ParseError, AuthenticationFailed, NotAuthenticated, PermissionDenied, NotFound, NotAcceptable, ValidationError, etc.

These will then get converted to a Response by the REST Framework's exception handler. Each exception is associated with a status code that is added to the Response. By default the exception handler is set to the built in handler:

REST_FRAMEWORK = {
    'EXCEPTION_HANDLER': 'rest_framework.views.exception_handler'
}

But you can set it to your own custom exception handler if you want to convert the exceptions yourself by changing this in your settings.py file:

REST_FRAMEWORK = {
    'EXCEPTION_HANDLER': 'my_project.my_app.utils.custom_exception_handler'
}

And then create the custom handler in that location:

from rest_framework.views import exception_handler

def custom_exception_handler(exc, context):
    # Call REST framework's default exception handler first,
    # to get the standard error response.
    response = exception_handler(exc, context)

    # Now add the HTTP status code to the response.
    if response is not None:
        response.data['status_code'] = response.status_code

    return response

edited Oct 12, 2017 at 20:12

answered Jun 3, 2015 at 18:38

emptyflash

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2 Comments

EngineSense Over a year ago

Import Error: Could not import 'my_project.my_app.utils.custom_exception_handler' for API setting 'EXCEPTION_HANDLER'. AttributeError: module my_project.my_app.utils' has no attribute 'custom_exception_handler'.

AlxVallejo Over a year ago

raise APIException("There was a problem!") isn't very helpful for anyone tho

oruchkin · Accepted Answer · 2022-12-13 18:18:25Z

10

You can use the build in DRF exception, just import and raise

from rest_framework.exceptions import ParseError
...
raise ParseError('I already have a status code!')

edited Dec 13, 2022 at 18:18

oruchkin

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answered May 29, 2015 at 11:43

haki

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3 Comments

felix001 Over a year ago

This just raises the exception. Shouldnt it also send the response ?

Ramast Over a year ago

Try raise APIException("this error will appear") or PermissionDenied, ValidationError Not sure about ParserError

emptyflash Over a year ago

@felix001 The exception gets converted to a Response, see my answer for more info

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