GraphQL error format - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is the standard structure of a GraphQL error response?

A GraphQL error response is a JSON object with an "errors" field, which is an array of error objects. Each error object typically contains a "message" describing the error, and may include "locations" (line and column), "path" (where in the query the error occurred), and "extensions" for additional info.

beginner

What does the "locations" field in a GraphQL error indicate?

The "locations" field shows the exact position(s) in the GraphQL query where the error happened, using line and column numbers. This helps developers quickly find the problem in their query.

intermediate

What is the purpose of the "path" field in a GraphQL error object?

The "path" field shows the path in the response data where the error occurred. It helps identify which part of the query's result caused the error, especially in nested queries.

intermediate

How can the "extensions" field in a GraphQL error be used?

The "extensions" field provides extra details about the error, such as error codes, classification, or custom metadata. It helps clients handle errors more precisely.

beginner

Why does GraphQL return partial data along with errors?

GraphQL can return partial data with errors to give clients as much useful information as possible, even if some parts of the query failed. This allows clients to handle errors gracefully and still use valid data.

What field in a GraphQL error object contains the human-readable error message?

A extensions

B locations

C path

D message

The "message" field contains the error description that explains what went wrong.

Which field helps locate the error in the GraphQL query by line and column?

A extensions

B path

C locations

D message

The "locations" field shows the line and column numbers where the error occurred in the query.

What does the "path" field in a GraphQL error indicate?

A The response data path where error happened

B The query location

C The error message

D Additional error metadata

The "path" shows where in the response data the error occurred, useful for nested queries.

Which field can contain custom error codes or classifications?

A extensions

B message

C locations

D path

The "extensions" field is used for extra error details like codes or classifications.

Why might a GraphQL response include both data and errors?

A Because the server is broken

B To provide partial data despite some errors

C To confuse the client

D Because errors always stop data delivery

GraphQL returns partial data with errors to give clients useful information even if some parts failed.

Describe the main fields in a GraphQL error object and their purposes.

Think about what info helps find and understand the error.

Explain why GraphQL might return partial data along with errors and how this benefits clients.

Consider how clients use data even when some parts fail.

Practice

1. What is the main purpose of the message field in a GraphQL error response?

easy

A. To describe what went wrong in the query

B. To show the exact line of code where the error occurred

C. To list all the fields requested in the query

D. To provide the user's authentication token

Solution

1. Step 1: Understand the role of the message field

   The message field clearly states the error description to help identify the problem.

2. Step 2: Compare with other fields

   Other fields like location show where the error happened, but message explains what the error is.

3. Final Answer:

   To describe what went wrong in the query -> Option A

4. Quick Check:

   message = error description [OK]

Hint: Message always explains the error clearly [OK]

Common Mistakes:

• Confusing message with location
• Thinking message holds query data
• Assuming message is optional

2. Which of the following is the correct structure of a GraphQL error object?

easy

A. { message: string, location: string, path: string }

B. { error: string, line: int, column: int, path: string }

C. { message: string, line: int, column: int, query: string }

D. { message: string, location: [{ line: int, column: int }], path: [string] }

Solution

1. Step 1: Recall GraphQL error object format

   GraphQL errors include message, location as an array of line and column objects, and path as an array of strings.

2. Step 2: Check each option's structure

   Only { message: string, location: [{ line: int, column: int }], path: [string] } matches the correct structure with proper types and nesting.

3. Final Answer:

   { message: string, location: [{ line: int, column: int }], path: [string] } -> Option D

4. Quick Check:

   Correct error object format = { message: string, location: [{ line: int, column: int }], path: [string] } [OK]

Hint: Look for location as array of line/column objects [OK]

Common Mistakes:

• Using location as a string
• Confusing path type with string instead of array
• Missing array brackets for location

3. Given this GraphQL error response snippet:

{"errors": [{"message": "Cannot query field 'age' on type 'User'", "locations": [{"line": 3, "column": 5}], "path": ["user", "age"]}]}

What does the path field indicate?

medium

A. The exact location in the query text where the error occurred

B. The sequence of fields leading to the error in the response data

C. The server file path where the error was logged

D. The user's file system path

Solution

1. Step 1: Understand the path field meaning

   The path shows the chain of fields in the response data that led to the error.

2. Step 2: Analyze the example path

   Here, the error is in the 'age' field inside the 'user' object, so path is ["user", "age"].

3. Final Answer:

   The sequence of fields leading to the error in the response data -> Option B

4. Quick Check:

   path = error location in response data [OK]

Hint: Path shows field chain causing error [OK]

Common Mistakes:

• Thinking path is query text location
• Confusing path with server file path
• Ignoring path as array of fields

4. You receive this GraphQL error response:

{"errors": [{"message": "Syntax Error: Expected Name, found }", "locations": [{"line": 5, "column": 10}]}]}

What is the most likely cause of this error?

medium

A. A missing or extra character in the query causing invalid syntax

B. A missing authentication token in the request headers

C. A server crash unrelated to the query

D. A network timeout error

Solution

1. Step 1: Interpret the error message

   The message says "Syntax Error: Expected Name, found }", indicating a syntax mistake in the query.

2. Step 2: Understand syntax errors in GraphQL

   Such errors happen when brackets, names, or punctuation are missing or misplaced in the query text.

3. Final Answer:

   A missing or extra character in the query causing invalid syntax -> Option A

4. Quick Check:

   Syntax error = query typo [OK]

Hint: Syntax errors mean query text is malformed [OK]

Common Mistakes:

• Assuming error is due to auth issues
• Confusing syntax error with server crash
• Ignoring location info in error

5. You want to add extra details to your GraphQL error responses for better debugging. Which field should you use to include custom error codes or metadata?

hard

A. locations

B. path

C. extensions

D. message

Solution

1. Step 1: Identify the field for extra error info

   The extensions field is designed to hold custom metadata like error codes or debugging info.

2. Step 2: Differentiate from other fields

   message is for error text, path shows error location in data, and locations shows query text position.

3. Final Answer:

   extensions -> Option C

4. Quick Check:

   extensions = custom error metadata [OK]

Hint: Use extensions for custom error details [OK]

Common Mistakes:

• Putting custom info in message
• Confusing path with metadata
• Ignoring extensions field existence