Input types in GraphQL - Mini Project: Build & Apply

GraphQL Input Types for User Registration

📖 Scenario: You are building a simple user registration system using GraphQL. Users will provide their details to sign up.

🎯 Goal: Create a GraphQL input type to collect user registration data, then use it in a mutation to add a new user.

📋 What You'll Learn

Define a GraphQL input type called UserInput with fields username (String!), email (String!), and age (Int).

Create a mutation called registerUser that accepts a UserInput argument named input.

The mutation should return a User type with fields id, username, and email.

💡 Why This Matters

🌍 Real World

Input types in GraphQL are used to send structured data from clients to servers, such as user registration forms or product details.

💼 Career

Understanding input types and mutations is essential for backend developers working with GraphQL APIs to handle data creation and updates.

1

Define the UserInput input type

Create a GraphQL input type called UserInput with these exact fields: username of type String!, email of type String!, and age of type Int.

GraphQL

# Your code here
type User {
  id: ID!
  username: String!
  email: String!
}

Need a hint?

Use the input keyword to define an input type. Fields must have types and exclamation marks for required fields.

2

Add the registerUser mutation

Add a mutation called registerUser that takes one argument named input of type UserInput! and returns a User type.

GraphQL

input UserInput {
  username: String!
  email: String!
  age: Int
}

type User {
  id: ID!
  username: String!
  email: String!
}

# Your code here

Need a hint?

Define a Mutation type with a field registerUser that takes input: UserInput! and returns User.

3

Add a Query type placeholder

Add an empty Query type to complete the schema structure.

GraphQL

input UserInput {
  username: String!
  email: String!
  age: Int
}

type User {
  id: ID!
  username: String!
  email: String!
}

type Mutation {
  registerUser(input: UserInput!): User
}

# Your code here

Need a hint?

GraphQL schemas need a Query type. Add a placeholder field like _empty: String if no queries yet.

4

Complete the schema with all types

Ensure the schema includes the UserInput input type, User type, Mutation type with registerUser, and the Query type with _empty.

GraphQL

input UserInput {
  username: String!
  email: String!
  age: Int
}

type User {
  id: ID!
  username: String!
  email: String!
}

type Mutation {
  registerUser(input: UserInput!): User
}

type Query {
  _empty: String
}

# Your code here

Need a hint?

Check that all parts of the schema are present and correctly named.