Scalar Types

GraphQL has a set of built-in scalars that are used to represent primitive types, in @graphql-ts/schema, these are accessible at g.Int, g.Float, g.String, g.Boolean, and g.ID.

Custom Scalars

You can define custom scalars using the g.scalar function. In general since you will likely want to use your custom scalars all around your schema, a common pattern is to include them in the g object like this:

schema.ts

import { gWithContext } from "@graphql-ts/schema";
import { GraphQLError } from "graphql";

const _g = gWithContext();

export const g = {
  ..._g,
  BigInt: _g.scalar({
    name: "BigInt",
    serialize(value) {
      if (typeof value === "bigint") {
        return value.toString();
      }
      throw new GraphQLError(
        "BigInt cannot represent non-bigint value: " + value
      );
    },
    parseValue(value) {
      if (typeof value === "bigint") {
        return value;
      }
      if (typeof value === "string") {
        return BigInt(value);
      }
      throw new GraphQLError("BigInt must be a string");
    },
    parseLiteral(ast) {
      if (ast.kind === "StringValue") {
        return BigInt(ast.value);
      }
      throw new GraphQLError("BigInt must be a string");
    },
  }),
};
export type g<T> = gWithContext.infer<T>;

schema.graphql

scalar BigInt

Tip

If you receive a TypeScript error like The inferred type of 'g' cannot be named without a reference to './node_modules/@graphql-ts/schema/src/types'. This is likely not portable. A type annotation is necessary., use the GWithContext type to be explicit about the type of g:

import { gWithContext, GWithContext } from "@graphql-ts/schema";
type Context = {};
const extra = {};
const g: GWithContext<Context> & typeof extra = {
  ...gWithContext(),
  ...extra,
};

Unlike all other GraphQL types in @graphql-ts/schema, the TypeScript types for scalars are exactly the same in @graphql-ts/schema as GraphQL.js so you can use GraphQLScalarType from GraphQL.js interchangably with g.scalar/GScalarType, For example, the above code can be rewritten using GraphQLScalarType:

schema.ts

import { gWithContext } from "@graphql-ts/schema";
import { GraphQLError, GraphQLScalarType } from "graphql";

export const g = {
  ...gWithContext(),
  BigInt: new GraphQLScalarType({
    name: "BigInt",
    serialize(value) {
      if (typeof value === "bigint") {
        return value.toString();
      }
      throw new GraphQLError(
        "BigInt cannot represent non-bigint value: " + value
      );
    },
    parseValue(value) {
      if (typeof value === "bigint") {
        return value;
      }
      if (typeof value === "string") {
        return BigInt(value);
      }
      throw new GraphQLError("BigInt must be a string");
    },
    parseLiteral(ast) {
      if (ast.kind === "StringValue") {
        return BigInt(ast.value);
      }
      throw new GraphQLError("BigInt must be a string");
    },
  }),
};
export type g<T> = gWithContext.infer<T>;

schema.graphql

scalar BigInt