graphql-to-io-ts
Custom templates for graphql-code-generator for generating both native typescript and io-ts types.
usage
yarn add -D graphql-code-generator graphql graphql-to-io-ts@0.2.1
```, then put something like the following in your `package.json`, then run `yarn generate-types`:
```json
{
"scripts": {
"generate-types": "gql-gen --template graphql-to-io-ts --schema ./schema/__generated__/schema.json --out schema/__generated__/io-types.ts './src/*/*/*.gql' --customScalars src/io-types/scalars"
}
}Custom Scalars
The templates support a custom generator config for custom scalars that you need to define in your gql-gen.json:
{
"generatorConfig": {
"customScalars": "src/io-types/scalars"
}
}It needs to export all the custom scalars used in your schema:
import * as t from 'io-ts'
import moment from 'moment'
// represents a Date from an ISO string
export const Datetime = new t.Type<moment.Moment, string>(
'Datetime',
(mixed): mixed is moment.Moment => moment.isMoment(mixed),
(mixed, context) =>
t.string.validate(mixed, context).chain(str => {
const instance = moment(str)
return instance.isValid() ? t.success(instance) : t.failure(str, context)
}),
instance => instance.toISOString()
)
export type Datetime = moment.MomentExamples
Tranit decoding, i.e. for apollo-client:
import * as t from 'io-ts'
import { Operations } from 'schema/__generated__/io-types'
type Op = { operationName: Operations.operationType }
export function decoder<O extends Op>(operation: O) {
return ({ data, ...response }) => ({
...response,
data: Operations[operation.operationName]
.Operation
.decode(data)
.getOrElseL(errors => {
let failures = failure(errors).join('\n');
console.error(failures);
throw new Error(failures)
})
})
}
