Error classification in GraphQL - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

Identify the error type from GraphQL query

What error type will this GraphQL query produce when executed if the field age does not exist in the schema?

GraphQL

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

A SyntaxError

B ValidationError

C ExecutionError

D AuthenticationError

💡 Hint

Think about errors caused by requesting fields not defined in the schema.

Requesting a field not defined in the schema causes a ValidationError because the query does not match the schema's structure.

❓ Predict Output

intermediate

Determine the error from a malformed GraphQL query

What error will this GraphQL query produce due to incorrect syntax?

GraphQL

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

A SyntaxError

B TimeoutError

C ExecutionError

D ValidationError

💡 Hint

Look for missing or extra braces or parentheses.

The query is missing a closing brace, causing a SyntaxError during parsing.

❓ Predict Output

advanced

Identify the error when a resolver throws an exception

What error type will be returned if a resolver function throws an exception during query execution?

GraphQL

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

A ExecutionError

B ValidationError

C SyntaxError

D AuthorizationError

💡 Hint

Consider errors that happen while fetching data, not parsing or validating.

ExecutionError occurs when the server fails to resolve a field during query execution due to exceptions.

❓ Predict Output

advanced

Classify the error caused by unauthorized access

What error will be returned if a user tries to access a field they do not have permission to see?

GraphQL

query {
  secretData {
    confidentialInfo
  }
}

A ValidationError

B AuthenticationError

C SyntaxError

D AuthorizationError

💡 Hint

Think about errors related to permission checks after authentication.

AuthorizationError occurs when a user is authenticated but lacks permission to access certain data.

🧠 Conceptual

expert

Distinguish error types in GraphQL lifecycle

Match each error type to the correct phase in the GraphQL request lifecycle where it typically occurs.

A 1: Authorization, 2: Execution, 3: Validation, 4: Parsing

B 1: Validation, 2: Parsing, 3: Authorization, 4: Execution

C 1: Parsing, 2: Validation, 3: Execution, 4: Authorization

D 1: Execution, 2: Authorization, 3: Parsing, 4: Validation

💡 Hint

Recall the order: parsing, validating, executing, then checking permissions.

SyntaxError happens during parsing, ValidationError during schema validation, ExecutionError during data fetching, and AuthorizationError during permission checks.