How to complete the challenge `POST /api/todos (422) extra`

How to complete the challenge `POST /api/todos (422) extra`

By Alan RichardsonPublished 2026-07-20

Issue a POST request to /api/todos with a field that is not part of the todo schema.

{
  "title": "create new todo",
  "doneStatus": false,
  "description": "created via API Challenges",
  "extra": "not part of the schema"
}

The response should be 422 Unprocessable Content because the payload is syntactically valid, but the todo data cannot be processed as a todo.

Try it now

POST /api/todos with an extra field to trigger 422

Lessons Learned

Strict request-body validation can reject fields that are syntactically valid JSON but outside the schema.
Extra-field tests reveal whether the API ignores unknown data or treats it as a client error.
422 Unprocessable Content here is about contract enforcement, not media type.

Suggested Experiments

Add one unknown property, then add two, and compare whether the error identifies all unexpected fields.
Remove only the extra property and confirm the same payload becomes a successful create.