Info argument in GraphQL - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ query_result

intermediate

Understanding the Info Argument Structure

Given a GraphQL resolver function that receives the info argument, what does info.fieldName return?

GraphQL

function resolver(parent, args, context, info) {
  return info.fieldName;
}

A The root query type name

B The entire GraphQL query string sent by the client

C The context object passed to all resolvers

D The name of the field currently being resolved

💡 Hint

Think about what part of the query the resolver is working on.

The info.fieldName property contains the name of the field that the resolver is currently resolving. It helps identify which field in the query is being processed.

❓ query_result

intermediate

Using Info to Access Requested Subfields

In a resolver, how can you use the info argument to find out which subfields the client requested for a nested object?

GraphQL

function resolver(parent, args, context, info) {
  // What property of info helps here?
  return Object.keys(info.fieldNodes[0].selectionSet.selections);
}

A info.schema.getType() returns the requested subfields

B info.fieldNodes[0].selectionSet.selections contains the requested subfields

C info.variableValues holds the subfield names

D info.rootValue contains the subfield list

💡 Hint

Look inside the AST nodes in the info argument.

The info.fieldNodes array contains the AST nodes for the current field. The first node's selectionSet.selections holds the subfields requested by the client.

📝 Syntax

advanced

Correct Usage of Info Argument in Resolver Signature

Which of the following resolver function signatures correctly includes the info argument as the fourth parameter?

A function resolver(parent, args, context, info) { return info.fieldName; }

B function resolver(info, parent, args, context) { return info.fieldName; }

C function resolver(parent, info, args, context) { return info.fieldName; }

D function resolver(parent, args, info) { return info.fieldName; }

💡 Hint

Remember the standard order of resolver parameters.

The standard resolver function parameters order is parent, args, context, then info. Only option A follows this order correctly.

🧠 Conceptual

advanced

Purpose of the Info Argument in GraphQL Resolvers

What is the main purpose of the info argument passed to GraphQL resolvers?

A To store user authentication tokens for security checks

B To hold the database connection object for queries

C To provide detailed information about the execution state, including the query AST and schema details

D To cache previous query results for faster responses

💡 Hint

Think about what extra data the resolver might need about the query itself.

The info argument contains the GraphQL query's abstract syntax tree (AST), schema information, and execution state, which helps resolvers understand the query structure and requested fields.

🔧 Debug

expert

Diagnosing a TypeError Using the Info Argument

A resolver function tries to access info.fieldNodes.selectionSet.selections but throws a TypeError: Cannot read property 'selectionSet' of undefined. What is the most likely cause?

GraphQL

function resolver(parent, args, context, info) {
  return info.fieldNodes.selectionSet.selections;
}

A info.fieldNodes is an array, so accessing selectionSet directly causes the error

B info.fieldNodes is null because the query is empty

C info.selectionSet is undefined because it does not exist on info

D The resolver forgot to pass the info argument

💡 Hint

Check the type of info.fieldNodes and how to access its elements.

info.fieldNodes is an array of AST nodes. Trying to access selectionSet directly on the array causes the error. The correct access is info.fieldNodes[0].selectionSet.