GQFn

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Enum ​

You need to use $enum if you want to define an enum in GQFn. Learn about enum

Specification ​

To use enum, you need to warp the value with $enum function.

ts
const query = gqfn([
  {
    toBytes: $ => $({ unit: $enum('MB'), value: 1000 }, true),
  },
])
graphql
{
  toBytes(unit: MB, value: 1000)
}

Why we need $enum?

If we have a toBytes field to get the number of bytes in a certain unit and we defined a enum to limit the input values.

graphql
enum UnitEnum {
  KB
  MB
  GB
  TB
}

type Query {
  toBytes(unit: UnitEnum, value: Int!): Int!
}

And make a query with query builder:

ts
const query = gqfn([
  {
    toBytes: $ => $({ unit: 'MB', value: 1000 }, true),
  },
])

In GraphQL, enums have a different syntax than strings, and they are not compatible with each other. But query builder is designed to be schema-independent, in this example the builder only know MB is a string, and it is impossible to determine whether the value is an enum or a string.

We need to make some different. As input object has used object, we can only use function or class, we choose function to wrap the enum value.

ts
const query = gqfn([
  {
    toBytes: $ => $({ unit: () => 'MB', value: 1000 }, true),
  },
])

Passing a function directly may lose type hints, so we provide a $enum wrapper.

ts
const query = gqfn([
  {
    toBytes: $ => $({ unit: $enum('MB'), value: 1000 }, true),
  },
])

You can use enum in variables without $enum wrapper.

ts
const query = gqfn('query', {
  unit: 'UnitEnum! = MB',
  value: 'Int!',
}, [
  {
    toBytes: $ => $({ unit: $.unit, value: $.value }, true),
  },
])

const data = client.query(query, {
  unit: 'MB',
  value: 1000,
})
graphql
query ($unit: UnitEnum! = MB, $value: Int!) {
  toBytes(unit: $unit, value: $value)
}

Type definition ​

ts
export type EnumPackage<T extends string> = () => T
export function $enum<T extends string>(content: T): EnumPackage<T>