Generating types for client

Pothos does not have a built in mechanism for generating types to use with a client, but graphql-code-generator can be configured to consume a schema directly from your typescript files.

Export your schema

The first thing you will need is a file that exports your built schema. The schema should be exported as schema or as the default export. This will be used to generate your client types, but can also be the schema you use in your server.

// schema.ts

// Import the builder
import builder from './builder';

// Import your type definitions
import './types/Query';
import './types/User';
import './types/Posts';

// Build and export the schema
export const schema = builder.toSchema();

Setting up graphql-code-generator

There are many different ways to set up graphql-code-generator, and the details depend a lot on your needs.

See the graphql-code-generator documentation for more details.

Install the codegen packages

yarn add graphql
yarn add -D typescript
yarn add -D @graphql-codegen/cli
yarn add -D @graphql-codegen/client-preset

Configure the codegen to import your schema

Create a codegen.ts file in the root of your project:

import type { CodegenConfig } from '@graphql-codegen/cli';
import { printSchema } from 'graphql';
import { schema } from './src/schema';

const config: CodegenConfig = {
  schema: printSchema(schema),
  documents: ['src/**/*.tsx'],
  generates: {
    './src/gql/': {
      preset: 'client',
      plugins: [],
    },
  },
};

export default config;

You can customize this config as needed, but the relevant parts are:

• Importing your GraphQL schema, this should be the result of calling builder.toSchema({})
• using printSchema from graphql to convert the schema to a string

Generating a schema.graphql file with graphql-code-generator

You can generate a schema.graphql file with graphql-code-generator by adding the schema-ast plugin:

yarn add -D @graphql-codegen/schema-ast

// codegen.ts
import { printSchema } from 'graphql';
import type { CodegenConfig } from '@graphql-codegen/cli';
import { schema } from './src/schema';

const config: CodegenConfig = {
  schema: printSchema(schema),
  documents: ['src/**/*.tsx'],
  generates: {
    './src/gql/': {
      preset: 'client',
      plugins: [],
    },
    'schema.graphql': {
      plugins: ['schema-ast'],
    },
  },
};

export default config;

Adding scalars

If you are using scalars (e.g. from graphql-scalars), you will need to add them to codegen.ts or else they will resolve to any. Here is an example for UUID and DateTime:

const config: CodegenConfig = {
  ...,
  config: {
    scalars: {
      UUID: 'string',
      DateTime: 'Date',
    },
  },
};

Alternatives

In some cases you may want to use an alternative method for loading you schema.

Printing the schema to a file

You can use the printSchema function from graphql to print your schema to a file, see Printing Schemas for more details:

By writing the schema to a file, you will be able to load the schema from a file instead importing it each time you want to generate your schema.

Having your schema written to a file, and checked into source control has many benifits, like easier code reviews, and better interoperability with other schema dependent graphql tools, so setting this up is worth while even if you do not need it for generating client types:

import type { CodegenConfig } from '@graphql-codegen/cli';

const config: CodegenConfig = {
  schema: './path/to/schema.graphql',
  documents: ['src/**/*.tsx'],
  generates: {
    './src/gql/': {
      preset: 'client',
      plugins: [],
    },
  },
};

export default config;

Using introspection from your dev (or production) server

Rather than using a schema SDL file, graphql-code-generator can also can use introspection to load your schema. To do this, you will need to ensure that your server has introspection enabled, most servers will have introspection enabled by default in development, and disabled in production.

You can then configure graphql-code-generator to use introspection by passing the URL to your graphql endpoint:

import type { CodegenConfig } from '@graphql-codegen/cli';

const config: CodegenConfig = {
  schema: 'https://localhost:3000/graphql',
  documents: ['src/**/*.tsx'],
  generates: {
    './src/gql/': {
      preset: 'client',
      plugins: [],
    },
  },
};

export default config;