Why error handling differs from REST in GraphQL

Introduction

Error handling in GraphQL is different from REST because GraphQL returns all data and errors together in one response. This helps clients get partial data even if some parts fail.

When you want to get multiple pieces of data in one request and still see which parts failed.

When you want to avoid multiple network calls to get related data.

When you want clear error messages tied to specific fields in your data.

When you want to handle errors without losing all the data in the response.

Syntax

GraphQL

GraphQL responses include two main parts:
{
  "data": { ... },
  "errors": [ ... ]
}

The data field contains the requested data, even if some errors occurred.

The errors field lists any problems found during the request.

Examples

This example shows a response where the user's name is returned, but the email field has an error. The error message explains the problem.

GraphQL

{
  "data": {
    "user": {
      "name": "Alice",
      "email": null
    }
  },
  "errors": [
    {
      "message": "Email not found",
      "path": ["user", "email"]
    }
  ]
}

This example shows a response where no data is returned because the user was not found. The error explains why.

GraphQL

{
  "data": null,
  "errors": [
    {
      "message": "User not found"
    }
  ]
}

Sample Program

This GraphQL query asks for a user's name and email by ID. If the email is missing or has an error, the response will include the name and an error message for the email.

GraphQL

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

Important Notes

GraphQL lets you get partial data even if some fields have errors, unlike REST which often returns a full error response.

Errors in GraphQL include a path to show exactly which field caused the problem.

Summary

GraphQL returns data and errors together in one response.

This allows clients to receive partial data even when some errors occur.

Error messages include the path to the problematic field for clarity.