How to Version GraphQL API: Best Practices and Examples

To version a GraphQL API, use schema evolution techniques like adding new fields, deprecating old ones with @deprecated, or create separate endpoints for major versions. Avoid breaking changes by evolving the schema carefully and communicating changes to clients.

Syntax

GraphQL versioning is often done by evolving the schema without breaking existing queries. Key parts include:

• @deprecated(reason: "message"): Marks fields or types as deprecated.
• Adding new fields or types without removing old ones.
• Optionally, using different endpoints or namespaces for major versions.

graphql

type Query {
  oldField: String @deprecated(reason: "Use newField instead")
  newField: String
}

Example

This example shows how to add a new field and deprecate an old one to version your API without breaking clients.

graphql

type Query {
  greeting: String @deprecated(reason: "Use welcomeMessage instead")
  welcomeMessage: String
}

# Resolver example in JavaScript
const resolvers = {
  Query: {
    greeting: () => "Hello!",
    welcomeMessage: () => "Welcome to the new API!"
  }
};

Output

{
  "data": {
    "welcomeMessage": "Welcome to the new API!"
  }
}

Common Pitfalls

Common mistakes when versioning GraphQL APIs include:

• Removing fields or changing types without deprecation, which breaks clients.
• Creating multiple endpoints unnecessarily, complicating client logic.
• Not communicating deprecations clearly to API consumers.

Instead, use @deprecated to mark fields and add new fields for new features.

graphql

type Query {
  # Wrong: removing oldField breaks clients
  # oldField: String

  # Right: deprecate oldField and add newField
  oldField: String @deprecated(reason: "Use newField instead")
  newField: String
}

Quick Reference

Versioning Strategy	Description	When to Use
Field Deprecation	Mark old fields with @deprecated and add new fields	Minor changes, backward compatible
Schema Evolution	Add new types and fields without removing old ones	Continuous improvements
Separate Endpoints	Use different URLs for major versions (e.g., /v1/graphql)	Major breaking changes
Namespace Types	Prefix types with version (e.g., UserV2)	When multiple versions run simultaneously

Key Takeaways

Use @deprecated directive to mark fields as outdated without breaking clients.

Add new fields or types to evolve your schema safely.

Avoid removing or changing existing fields abruptly.

Consider separate endpoints only for major breaking changes.

Communicate version changes clearly to API consumers.