Required fields with non-null (!) in GraphQL - Mini Project: Build & Apply

GraphQL Required Fields with Non-Null (!) Project

📖 Scenario: You are building a simple GraphQL API for a bookstore. You want to make sure that certain important fields like title and author of a book are always provided and never left empty.

🎯 Goal: Create a GraphQL schema that defines a Book type with required fields using the non-null ! symbol. Then write a query to fetch books ensuring the required fields are always returned.

📋 What You'll Learn

Define a Book type with title and author as required fields using !

Create a query type Query with a field books that returns a list of Book

Write a sample query to fetch title and author from books

💡 Why This Matters

🌍 Real World

GraphQL APIs often require certain fields to always be present to avoid errors and ensure data integrity, such as user names, product titles, or book authors.

💼 Career

Understanding how to use non-null fields in GraphQL is essential for backend developers and API designers to create robust and reliable APIs.

1

Define the Book type with required fields

Create a GraphQL type called Book with two fields: title and author. Both fields must be of type String! to make them required (non-null).

GraphQL

# Your code here
type Book {
  # Define title and author as required fields
}

Need a hint?

Use String! to mark a field as required (non-null).

2

Add the Query type with books field

Add a Query type with a field called books that returns a list of Book objects. Use [Book!]! to indicate the list and its items are required.

GraphQL

type Book {
  title: String!
  author: String!
}

# Your code here
type Query {
  # Define books field returning a non-null list of non-null Book
}

Need a hint?

Use [Book!]! to say the list and each book inside it cannot be null.

3

Write a sample query to fetch required fields

Write a GraphQL query named GetBooks that fetches the title and author fields from the books query.

GraphQL

type Book {
  title: String!
  author: String!
}

type Query {
  books: [Book!]!
}

# Your code here
query GetBooks {
  books {
    # Select title and author
  }
}

Need a hint?

Inside the books field, select both title and author.

4

Complete the schema with required fields and query

Combine the Book type and Query type with the books field into a complete GraphQL schema. Ensure all required fields use ! and the query is ready to fetch title and author.

GraphQL

# Your code here
# Combine all parts into one schema

Need a hint?

Make sure the schema and query are complete and consistent with required fields.