Union types in GraphQL - Mini Project: Build & Apply

GraphQL Union Types for Media Library

📖 Scenario: You are building a media library database that stores different types of media items: Books and Movies. Each media type has its own unique fields.To efficiently query these different media types in one request, you will use GraphQL union types.

🎯 Goal: Create a GraphQL schema that defines Book and Movie types, then create a union type called MediaItem that can represent either a Book or a Movie. Finally, define a query mediaLibrary that returns a list of MediaItem.

📋 What You'll Learn

Define a Book type with fields id (ID!), title (String!), and author (String!).

Define a Movie type with fields id (ID!), title (String!), and director (String!).

Create a union type called MediaItem that includes Book and Movie.

Define a Query type with a field mediaLibrary that returns a list of MediaItem.

💡 Why This Matters

🌍 Real World

Union types let you query different types of related data in one request, useful in media libraries, e-commerce, or social networks.

💼 Career

Understanding union types is important for building flexible GraphQL APIs that handle multiple data types efficiently.

1

Define the Book and Movie types

Create a GraphQL schema that defines a Book type with fields id of type ID!, title of type String!, and author of type String!. Also define a Movie type with fields id of type ID!, title of type String!, and director of type String!.

GraphQL

# Define Book and Movie types here

Need a hint?

Use type keyword to define both Book and Movie types with their respective fields.

2

Create the MediaItem union type

Add a union type called MediaItem that includes Book and Movie.

GraphQL

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

type Movie {
  id: ID!
  title: String!
  director: String!
}

# Define the MediaItem union type here

Need a hint?

Use the union keyword followed by the union name and the types separated by |.

3

Define the Query type with mediaLibrary field

Add a Query type with a field called mediaLibrary that returns a list of MediaItem (use square brackets).

GraphQL

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

type Movie {
  id: ID!
  title: String!
  director: String!
}

union MediaItem = Book | Movie

# Define Query type with mediaLibrary field here

Need a hint?

Define a Query type with a field mediaLibrary that returns a list of MediaItem using square brackets.

4

Complete the schema with schema definition

Add the schema definition that sets the query root type to Query.

GraphQL

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

type Movie {
  id: ID!
  title: String!
  director: String!
}

union MediaItem = Book | Movie

type Query {
  mediaLibrary: [MediaItem]
}

# Add schema definition here

Need a hint?

Use the schema keyword and set query: Query to complete the schema.