Schema evolution strategies in GraphQL - Mini Project: Build & Apply

Schema Evolution Strategies in GraphQL

📖 Scenario: You are working on a GraphQL API for a book store. Over time, the schema needs to evolve without breaking existing clients. You will practice adding new fields, deprecating old fields, and introducing new types safely.

🎯 Goal: Build a GraphQL schema that demonstrates schema evolution strategies: adding new fields, marking fields as deprecated, and adding new types while keeping backward compatibility.

📋 What You'll Learn

Create an initial GraphQL schema with a Book type containing id, title, and author fields.

Add a new optional field publishedYear to the Book type.

Deprecate the author field with a reason.

Add a new type Author with id and name fields and update Book to reference Author instead of a string.

💡 Why This Matters

🌍 Real World

APIs evolve over time. Schema evolution strategies help keep APIs stable while adding new features or improving data models.

💼 Career

Understanding schema evolution is essential for backend developers and API designers to maintain backward compatibility and improve client experience.

1

Create initial Book type

Create a GraphQL type called Book with fields id of type ID!, title of type String!, and author of type String!.

GraphQL

# Define the Book type with id, title, and author fields
# Your code here

Need a hint?

Use type Book { ... } and define the fields with their types exactly as specified.

2

Add publishedYear field

Add a new optional field called publishedYear of type Int to the existing Book type.

GraphQL

type Book {
  id: ID!
  title: String!
  author: String!
  # Add publishedYear field here
}

Need a hint?

Remember that optional fields do not have an exclamation mark !.

3

Deprecate author field

Mark the author field in the Book type as deprecated with the reason Use the author field with type Author instead.

GraphQL

type Book {
  id: ID!
  title: String!
  # Deprecate author field here
  author: String! @deprecated(reason: "Use the author field with type Author instead")
  publishedYear: Int
}

Need a hint?

Use the @deprecated directive with the reason argument exactly as shown.

4

Add Author type and update Book

Create a new GraphQL type called Author with fields id of type ID! and name of type String!. Then update the Book type to replace the deprecated author field with a new field author of type Author!.

GraphQL

type Book {
  id: ID!
  title: String!
  author: Author!
  publishedYear: Int
}

# Define Author type here

Need a hint?

Define the new Author type first, then update the author field in Book to use Author!.