Скачать или смотреть How to TypeScript Types for GraphQL Query and Mutation Fields

Discover how to effectively get typed arguments and parent properties in your GraphQL queries and mutations using TypeScript. Learn step-by-step solutions to improve your GraphQL API with proper typing.
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Getting TypeScript Types for GraphQL Query and Mutation Fields

If you're a developer navigating the integration of TypeScript with GraphQL, you may have stumbled upon a common obstacle: typing the arguments and parent properties in your GraphQL queries and mutations. This can often lead to confusion and frustration, especially when trying to achieve a fully typed API. In this guide, we'll break down how to handle TypeScript types in your GraphQL queries and mutations effectively.

Understanding the Problem

When defining your GraphQL schema and resolvers, it's essential to have proper typing for your arguments (args) and parent properties (parent). This improves code safety and helps catch potential errors early during development. Let's take a look at what we want to achieve:

Typed Arguments: Utilize TypeScript types for the arguments passed to the resolvers.

Typed Parent Properties: Ensure that the parent property is also typed correctly for accessing its fields.

Let's illustrate this with an example.

Example Server Context Setup

We'll start with the server setup where we define the server context and schema.

[[See Video to Reveal this Text or Code Snippet]]

Defining the Root Query

In the root query, we define the types for our fields.

[[See Video to Reveal this Text or Code Snippet]]

In the example above, notice how parent is inferred as any and args as [argName: string]: any;.

The Solution to Typing

You'll find that typing args cannot be done automatically for safety reasons, as GraphQL arguments can be anything. However, here's how you can address this:

Step 1: Define Command Input Types

Create an input type for your arguments.

[[See Video to Reveal this Text or Code Snippet]]

Step 2: Type the Parent and Args Manually

Modify your resolvers to explicitly define the types for parent and args. For instance:

[[See Video to Reveal this Text or Code Snippet]]

Step 3: Utilize TypeScript Interfaces

By accurately defining TypeScript interfaces for your parent and argument types, you can ensure that TypeScript checks for correct usage throughout your resolvers.

Conclusion

While initially intimidating, working with TypeScript in GraphQL can be streamlined by correctly setting up input types and explicitly defining types in your resolvers. Remember that GraphQL does not inherently enforce types—this is the role of TypeScript.

By adopting these practices, you will have a more robust, maintainable, and type-safe GraphQL API.

Feel free to implement these strategies in your project, and watch your development experience improve dramatically!