How We Ditched Manual GraphQL Schema Definition with Pylon
Tags: graphql, typescript, api, webdev
Published: 2024-07-01 15:58:48

[![Pylon Hero Section](https://github.com/getcronit/pylon/assets/52858351/9ce5833f-c4ce-4dc5-85a9-6eb3910b40bd)](https://pylon.cronit.io)

In the ever-evolving landscape of web development, efficiency and scalability are paramount. One of the significant challenges developers face is managing and composing GraphQL schemas, especially as projects grow in size and complexity. Manual schema composition can become a cumbersome task, prone to errors and difficult to maintain. Enter Pylon, a game-changer in the world of GraphQL.

## The Challenge of Manual GraphQL Schema Definition

GraphQL, with its powerful query language and flexible APIs, has revolutionized how developers interact with data. However, constructing and maintaining the schema, which defines the types and relationships within the API, often requires meticulous manual effort. This process involves:

1. **Defining Types and Resolvers**: Manually writing type definitions and resolvers in a schema file.
2. **Ensuring Consistency**: Keeping the type definitions in sync with the underlying data models and resolvers.
3. **Handling Scalability**: As the application grows, the schema becomes more complex, making it harder to manage.
4. **Reducing Errors**: Avoiding typos and logical errors in the schema definition.

These challenges not only slow down development but also introduce potential bugs and inconsistencies.

## Introducing Pylon

Pylon is a revolutionary tool that automates GraphQL schema composition based on your TypeScript functions. By leveraging the type annotations already present in your TypeScript code, Pylon generates a fully-formed GraphQL schema, reducing the need for manual intervention. Here’s how Pylon addresses the key challenges of manual schema composition:

**1. Simplified Schema Definition**

With Pylon, developers no longer need to manually define types and resolvers. Pylon scans your TypeScript functions, infers the types, and automatically generates the corresponding GraphQL schema. This eliminates the need for duplicative code and ensures that your GraphQL schema is always in sync with your application logic.

**2. Consistency and Type Safety**

Since Pylon relies on TypeScript’s type system, it ensures that the generated GraphQL schema is consistent with the types defined in your code. Any changes to your TypeScript types are automatically reflected in the GraphQL schema, reducing the risk of discrepancies. This tight coupling between TypeScript and GraphQL promotes type safety across your application.

**3. Scalability and Maintainability**

Pylon’s automated approach to schema generation significantly improves scalability. As your codebase grows, Pylon continues to generate and update the schema, handling the complexity behind the scenes. This makes it easier to manage large and evolving projects, freeing developers to focus on building features rather than maintaining schema files.

**4. Error Reduction**

By eliminating manual schema definitions, Pylon reduces the likelihood of errors. Developers can trust that the schema accurately represents the underlying data models and functions. This leads to fewer bugs and a more robust application overall.

## How Pylon Works

Using Pylon is straightforward and simplifies your GraphQL development workflow. Here’s a quick overview of how to get started:

**Step 1: Install Pylon CLI**

To begin using Pylon, install the Pylon CLI globally using npm:

```bash
npm install -g @getcronit/pylon-cli
```

**Step 2: Create a New Pylon Project**

Create a new Pylon project using the CLI. This command initializes a new project structure with necessary configurations:

```bash
pylon new my-pylon-project
```

**Step 3: Annotate TypeScript Functions**

In your Pylon project, define TypeScript functions annotated with Pylon directives to specify GraphQL queries, mutations.

```typescript
import { defineService } from "@getcronit/pylon";

class StarWarsStore {
  private characters = [
    { id: 1, name: "Luke Skywalker", height: 172 },
    { id: 2, name: "Darth Vader", height: 202 },
  ];

  constructor() {
    // Bind methods in order to access `this`
    this.getCharacter = this.getCharacter.bind(this);
    this.getCharacters = this.getCharacters.bind(this);
    this.addCharacter = this.addCharacter.bind(this);
    this.deleteCharacter = this.deleteCharacter.bind(this);
  }

  getCharacter(id: number) {
    return this.characters.find((character) => character.id === id);
  }

  getCharacters() {
    return this.characters;
  }

  addCharacter(name: string, height: number) {
    const id = this.characters.length + 1;
    this.characters.push({ id, name, height });
    return { id, name, height };
  }

  deleteCharacter(id: number) {
    const character = this.getCharacter(id);
    if (character) {
      this.characters = this.characters.filter((c) => c.id !== id);
      return character;
    }
    return null;
  }
}

const store = new StarWarsStore();

export default defineService({
  Query: {
    character: store.getCharacter,
    characters: store.getCharacters,
  },
  Mutation: {
    addCharacter: store.addCharacter,
    deleteCharacter: store.deleteCharacter,
  },
});
```

In this example, `defineService` from Pylon defines GraphQL queries (`sum`) and mutations (`divide`), which perform simple arithmetic operations.

**Step 4: Run the Development Server**

Start the development server using the provided command (`bun run develop` in this case) to launch your GraphQL API with the generated schema:

```bash
bun run develop
```

**Step 5: Explore Your GraphQL API**

With the development server running, you can explore your GraphQL API using the built-in GraphQL Playground, the GraphQL viewer, or any other GraphQL client.

- **GraphQL Playground**: Access the GraphQL Playground at `http://localhost:3000/graphql` to interact with your API, run queries, and explore the schema.

![GraphQL Playground Example](https://dev-to-uploads.s3.amazonaws.com/uploads/articles/u7dwbnuddyn5duh5evab.png)

- **GraphQL Viewer**: Use the GraphQL viewer at `http://localhost:3000/viewer` to visualize the schema and understand the available queries and mutations.

![GraphQL Viewer Example](https://dev-to-uploads.s3.amazonaws.com/uploads/articles/1naav3oo8lfe4s00nyp3.png)



## Advanced usage

- **Built-in Authentication and Authorization**: Pylon provides built-in support for authentication and authorization, allowing you to secure your GraphQL API with ease. By integrating with [ZITADEL](https://zitadel.com/docs/examples/secure-api/pylon), Pylon simplifies user management and access control.
- **Logging and Monitoring**: Pylon integrates with Sentry to provide real-time error monitoring and alerting for your Pylon service. Check out the guide on [logging and monitoring](https://pylon.cronit.io/docs/logging-and-monitoring) for more details.
- **Context Management**: Pylon allows you to access the request context anywhere in your service functions, enabling you to implement custom logic based on the incoming request. Learn more about [context management](https://pylon.cronit.io/docs/context-management) in the Pylon documentation.
- **Deployment**: To deploy your Pylon service, follow the deployment guide in the [official documentation](https://pylon.cronit.io/#deploying-to-production) to get your service up and running in production.

## Conclusion

Pylon has transformed our approach to GraphQL schema definition. By leveraging the power of TypeScript, it automates the generation of schemas, ensuring consistency, scalability, and error reduction. This shift from manual to automated schema definition has allowed us to focus more on developing features and less on maintaining boilerplate code. If you’re looking to streamline your GraphQL development process, Pylon is a tool worth exploring. It’s a testament to how modern tools can enhance productivity and maintainability in web development.

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For more information on Pylon and its features, check out the [official documentation](https://pylon.cronit.io/docs/introduction) or the [GitHub repository](https://github.com/getcronit/pylon) to get started with Pylon today!