GraphQL: Schema-First vs Code-First

Overview

The Schema-First approach emphasizes defining the schema using GraphQL Schema Definition Language (SDL) before implementing the resolver logic in your application. This separation of concerns helps in visualizing the API structure clearly.

Step-by-Step Process

1. Define your GraphQL schema using SDL.
2. Create resolver functions that match the schema definition.
3. Integrate the schema and resolvers in your GraphQL server setup.

Example

type Query {
    hello: String
}
                

const resolvers = {
    Query: {
        hello: () => 'Hello, world!'
    }
};
                

Overview

The Code-First approach allows developers to define GraphQL types using native programming language classes or types. This method integrates schema definition and resolver logic more tightly.

Step-by-Step Process

1. Create classes or types that represent your GraphQL schema.
2. Use decorators or annotations to define schemas and resolvers.
3. Generate the GraphQL schema from your code structure.

Example

const { ObjectType, Field, ID, buildSchema } = require('type-graphql');

@ObjectType()
class Hello {
    @Field(() => String)
    hello() {
        return 'Hello, world!';
    }
}

const schema = buildSchema({
    resolvers: [Hello],
});
                

Key Differences

• Schema-First focuses on schema definition, while Code-First integrates it into application code.
• Schema-First often provides better separation of concerns.
• Code-First allows for more dynamic and programmatic schema definitions.

Recommendations

• Choose based on team preference and project requirements.
• Keep a consistent structure for easier maintenance and scalability.
• Utilize tools such as GraphQL Playground for testing your API.