Resolver function signature in GraphQL - Mini Project: Build & Apply

GraphQL Resolver Function Signature

📖 Scenario: You are building a simple GraphQL API for a bookstore. You need to write resolver functions that fetch data when a client queries the API.

🎯 Goal: Learn how to write a basic resolver function signature in GraphQL that accepts parent, args, context, and info parameters.

📋 What You'll Learn

Create a resolver function named bookResolver

The function must accept exactly four parameters: parent, args, context, and info

The function should return a placeholder string 'Resolver called'

💡 Why This Matters

🌍 Real World

GraphQL resolvers are the core functions that fetch and return data when clients query your API.

💼 Career

Understanding resolver signatures is essential for backend developers working with GraphQL APIs in many companies.

1

Create the resolver function skeleton

Write a function named bookResolver that accepts four parameters: parent, args, context, and info. For now, the function body can be empty.

GraphQL

# Write the function signature for bookResolver with parameters parent, args, context, info
# Your code here

Need a hint?

Remember, a resolver function always receives these four parameters in this order.

2

Add a return statement

Inside the bookResolver function, add a return statement that returns the string 'Resolver called'.

GraphQL

function bookResolver(parent, args, context, info) {
    // Return the string 'Resolver called'
    // Your code here
}

Need a hint?

Use return 'Resolver called'; inside the function body.

3

Explain the parameters in comments

Add comments inside the bookResolver function explaining the purpose of each parameter: parent, args, context, and info.

GraphQL

function bookResolver(parent, args, context, info) {
    // parent: contains result from previous resolver
    // args: contains arguments passed to the query
    // context: shared data like authentication info
    // info: query execution details
    return 'Resolver called';
    // Your code here
}

Need a hint?

Write one comment line for each parameter inside the function.

4

Export the resolver function

Add a line to export the bookResolver function as the default export.

GraphQL

function bookResolver(parent, args, context, info) {
    // parent: contains result from previous resolver
    // args: contains arguments passed to the query
    // context: shared data like authentication info
    // info: query execution details
    return 'Resolver called';
}

// Export the resolver function
// Your code here

Need a hint?

Use export default bookResolver; to export the function.