Field-level errors in GraphQL

Introduction

Field-level errors help you know exactly which part of your data request has a problem. This makes fixing issues faster and clearer.

When a user submits a form and some fields have wrong or missing data.

When fetching data and some fields fail but others succeed.

When you want to show specific error messages next to each input field in an app.

When debugging which part of a query caused an error.

When you want to keep showing valid data even if some fields have errors.

Syntax

GraphQL

query {
  user(id: "123") {
    name
    email
    posts {
      title
      content
    }
  }
}

# If an error happens in 'email', the response will include an 'errors' array with details about that field.

Field-level errors appear in the 'errors' part of the GraphQL response.

Errors include a 'path' showing which field caused the problem.

Examples

If 'email' is invalid or missing, the error will point to ['user', 'email'].

GraphQL

query {
  user(id: "123") {
    name
    email
  }
}

If 'reviews.rating' has an error, the error path will show ['product', 'reviews', 0, 'rating'] for the first review.

GraphQL

query {
  product(id: "456") {
    name
    price
    reviews {
      rating
      comment
    }
  }
}

Sample Program

This query asks for a user with id "999". If the user does not exist or the email field has an error, the response will show which field caused the problem.

GraphQL

query {
  user(id: "999") {
    name
    email
  }
}

Important Notes

Field-level errors let you handle partial failures gracefully.

Always check the 'errors' array in the response to find these errors.

Errors include a 'path' array to help you locate the exact field with the problem.

Summary

Field-level errors show exactly which part of a query failed.

They help apps show clear messages next to problem fields.

Errors include a path to find the field causing the issue.