Unlock the Power of GraphQL Enums

Simplifying Data Querying for Modern Frontend Applications

GraphQL has revolutionized the way we query data, making it faster, more efficient, and scalable. As the technology of choice for many industry giants, including Github, Netflix, and Shopify, GraphQL has proven itself to be a production-ready tool. However, one often overlooked aspect of GraphQL is the humble enum type. In this article, we’ll explore the importance of enums in building robust GraphQL APIs and how they can simplify data querying.

The Problem with Strings

When using strings to filter data, we can introduce issues at multiple levels. Strings are case-sensitive, which can lead to unexpected errors, silent failures, or even security vulnerabilities. Moreover, exposing internal values can go against the principle of APIs providing a simple, decoupled interface with data. This is where enums come in – to provide a more robust and discoverable API.

The Benefits of Enums

• Improved Validation: Enums limit the possible values, avoiding duplicate validation logic and ensuring that only valid values are accepted.
• Enhanced Discoverability: Enums are introspectable, allowing tools like GraphiQL to provide autocomplete functionality and generate corresponding TypeScript types.
• Simplified Interface: Enums abstract internal values to simple choices, making it easier for developers to interact with the API.

Migrating to Enums

To make our GraphQL schema more robust, we can migrate from strings to enums. We’ll define our enums using the enum keyword and update our schema to use these new types. With Apollo Server, each enum value will resolve to its string equivalent, and we can provide enum resolvers to map internal values to their corresponding enum values.

enum AuthType {
  GITHUB
  GOOGLE
  EMAIL
}

Querying with Enums

With enums, our queries become safer, typoless, and fully discoverable. We can now filter users by auth type using our AuthType enum, ensuring that only valid values are accepted.

query {
  users(authType: GITHUB) {
    id
    name
  }
}

Bonus: TypeScript Generation

GraphQL enums are introspectable, which means that tools like GraphQL Code Generator will generate the corresponding TypeScript enum type for our frontend application. This enables a robust and powerful developer experience.

enum AuthType {
  GITHUB = 'GITHUB',
  GOOGLE = 'GOOGLE',
  EMAIL = 'EMAIL',
}