Add error messages that tell you which field is incorrect to the API. Proposed: Problem Details

[RonSijm]

Requirements

• [X] Is this a feature request? For questions or discussions use https://lemmy.ml/c/lemmy_support
• [X] Did you check to see if this issue already exists?
• [X] Is this only a feature request? Do not put multiple feature requests in one issue.
• [X] Is this a backend issue? Use the lemmy-ui repo for UI / frontend issues.

Is your proposal related to a problem?

I'm using a client to consume the API, and it's difficult to understand what data is incorrect

For example:

• Create Community:

  • Send request "Banner == "example"
  • Receive response: {"error":"invalid_url"}
  • Proposed response:
  • { "errors" { "Banner" [ "The Bannner field should be a valid uri"] }} (json)

• Create Community:

  • Send request "DiscussionLanguages == "123.123"
  • Receive response: Json deserialize error: invalid type: floating point '123.123', expected i32 at line 1 column 139 (Not even Json)
  • Proposed response:
  • { "errors" { "DiscussionLanguages" [ "The DiscussionLanguages field should be a valid int"] }}

These are just 2 examples of course, I would propose to respond with better details of everything could go wrong

Describe the solution you'd like.

Have a look at:

• https://datatracker.ietf.org/doc/html/rfc7807 "Problem Details for HTTP APIs"
• https://zuplo.com/blog/2023/04/11/the-power-of-problem-details "The Power of Problem Details for HTTP APIs"
• https://codeopinion.com/problem-details-for-better-rest-http-api-errors/ "Problem Details for Better REST HTTP API Errors"

Describe alternatives you've considered.

Responses like Json deserialize error: invalid type: floating point '123.123', expected i32 at line 1 column 139 as plain text are even more difficult to understand. As a quickfix there should be a global error handler that wraps unexpected errors into json

[Nutomic]

This is a problem in actix-web, upstream issue here: https://github.com/actix/actix-web/issues/1684

There is also an open pull request but its unfinished since two years: https://github.com/actix/actix-web/pull/2376