Documentation
Essentials
Type Definitions (SDL)

Type Definitions

GraphQL Schema is built out of types, enums, interfaces and so on. Defining or extending them in GraphQL Modules is fairly simple.

Just like GraphQL Schema, GraphQL Modules follow the same rules of writing SDL (Schema Definition Language), a single definition per type and multiple extensions. This way we force a good pattern and clarify ownership of each type.

To get started with type definitions in your module, make sure to use gql (you can import it from graphql-modules) or parse (from graphql) to convert your string SDL definition into a DocumentNode object.

import { createModule, gql } from 'graphql-modules'
 
export const myModule = createModule({
  id: 'my-module',
  dirname: __dirname,
  typeDefs: gql`
    type Query {
      user(id: ID!): User
    }
 
    type User {
      id: ID!
      username: String!
    }
  `
})
⚠️

Using strings could be possible, but we decided to force a better pattern. Using gql tag means your IDE can highlight the GraphQL SDL and in general works better with other tools from the GraphQL ecosystem.

💡

TIP: typeDefs can be a single item or an array of multiple.

Storing SDL in .graphql Files

If you wish to write your GraphQL SDL in a .graphql file, you need to make sure you can load it correctly in a Node.js environment.

To do so, use graphql-import-node to make this process easier:

Start by installing it, and follow the installation instructions, based on your environment and your setup.

Now, store your SDL in a .graphql file(s), and load it this way, with import or require:

import MyQueryType from './query.type.graphql'
import { createModule } from 'graphql-modules'
 
export const myModule = createModule({
  id: 'my-module',
  dirname: __dirname,
  typeDefs: [MyQueryType]
})

Dynamically Load SDL Files

If you have too many SDL files, and you wish to load them dynamically, you can use loaders from @graphql-tools/load-files!

Start by installing this package:

npm i @graphql-tools/load-files

Next, use it to load your files dynamically:

import MyQueryType from './query.type.graphql'
import { createModule } from 'graphql-modules'
import { loadFilesSync } from '@graphql-tools/load-files'
import { join } from 'node:path'
 
export const myModule = createModule({
  id: 'my-module',
  dirname: __dirname,
  typeDefs: loadFilesSync(join(__dirname, './typeDefs/*.graphql'))
})
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Note: the default implementation of loadFilesSync is using fs module. If you are using graphql-import-node, you can add a 2nd parameter with configuration: { useRequire: true }.

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