Return error code when handling django errors

[thclark]

Feature Request Type

• Core functionality
• Alteration (enhancement/optimization) of existing feature(s)
• New behavior

Description

When consuming an API, it's very helpful to be able to act on an error code that gets returned. For example in apollo server, errors get a code attached. The total set of codes being limited, this allows you to write a single piece of error handling code on your client and use it on most queries.

I've noticed we don't do that when handling django errors; all we get is a path and a message:

The problem is that client-side, I now need to parse that error message. The only way I can know what happened is to parse the specific error message, ie do:

const response = {
  data: null,
  errors: [
    {
      message: "Organisation matching query does not exist.",
      locations: [
        {
          line: 2,
          column: 3
        }
      ],
      path: ["organisation"]
    }
  ]
};

// Check if the specific error message exists in the errors list
const errorExists = response.errors?.some(error => error.message === "Organisation matching query does not exist.");

console.log(errorExists); // true if the message exists, false otherwise

This means we have to write custom error handling code for each query on the frontend side, which knows the specific message patterns produced by django.

A further concern

The messages that are produceable currently are not included in the schema either, so you're kind of left in the dark as to what could happen error-wise. Having a set of error codes that could result from any given query (or even a set from all queries) would be massively helpful in knowing what you have to do to handle them.

Proposed Solution

My colleage @cortadocodes had the idea that django errors have a type associated with them. The example error shown above was generated on the query:

@strawberry.type()
class OrganisationQueries:

    @strawberry.field
    def organisation(self, handle: str) -> OrganisationType:
        return Organisation.objects.get(handle=handle)

Now if you do:

try:
    Organisation.objects.get(handle="not-anyones-handle")
except Organisation.DoesNotExist as e:
    code = type(e).__name__  // This is "DoesNotExist"
    message=str(e)  // This is the message we get already

Do you think we could add this code to handled django error messages? It'd make error handling a lot more powerful, especially around auth and permissions workflows where codes like Unauthenticated and Forbidden could have completely generic error handling code on the client side.

@bellini666 If you think this is viable, I'm happy to sponsor the work, let's chat?

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[bellini666]

Hi @thclark ,

That's the basic idea of why we have the django errors handling, but I agree that it doesn't solve everything.

And yes, let's chat about that! :)

Can you send me a PM on discord so we can schedule a call for this?