nestjs-graphql-utils

@jenyus-org/nestjs-graphql-utils is a collection of utilities and decorators built on top of @jenyus-org/graphql-utils to encourage the stateless nature of NestJS GraphQL resolvers and simplify the usage of helpers.

Installation

@jenyus-org/nestjs-graphql-utils can be installed from NPM by running one of the following commands:

NPM:

npm i --save @jenyus-org/nestjs-graphql-utils

Yarn:

yarn add @jenyus-org/nestjs-graphql-utils

This will install @jenyus-org/nestjs-graphql-utils and all its dependencies.

Usage

All the utilities provided by @jenyus-org/nestjs-graphql-utils are exported directly by the package with Typescript definitions. All the functions and decorators are described below.

Decorators

@HasFields(...fields: (string | string[])[]): boolean

@HasFields() uses the received GraphQLResolveInfo from the incoming request, to run hasFields for every argument passed. Just like hasFields it supports array syntax and dot notation, and uses AND bitwise operations ensuring that every field passed resolves to true.

Example usage in a GraphQL resolver:

@Query(() => UserObject, { nullable: true })
async user(
  @HasFields("user.username") wantsUsername: boolean,
) {
  console.log(wantsUsername);
}

Given the following query, true will be printed to the console:

{
  user {
    username
  }
}

@Selections(fieldSelections: string | string[] | FieldSelections[], fields?: string[], asParent: boolean = true): string[]

Similar to @HasFields(), @Selections acts as a layer on top of resolveSelections, and additionally contains some logic to solve the most common use-case.

fieldSelections can be the same type of argument as accepted by resolveSelections, and will return an array of selectors which were found in the query.

Additionally, instead of passing the field selection array, users may pass a simple string, acting as the root object for subsequent fields. In this case the second argument, fields is required, and must be an array of strings to search within the parent selector.

Take the following example:

@Query(() => UserObject, { nullable: true })
async user(
  @Selections("user", ["username", "firstName"]) fieldSelections: string[]
) {
  console.log(fieldSelections);
}

If the query includes the selections username and firstName, unlike passing a similar argument structure directly to resolveSelections, @Selections() will generate the following array:

["user.posts", "user.profile"]

Note: Internally @Selections will remap the fields array to the fields, prepended by the parent, similar to what is shown in the README of graphql-utils.

To disable the behavior of remapping, and simply use the fields array as-is, a third argument asParent, which defaults to true, can be passed as false. Resulting in the following output:

["posts", "profile"]

This will continue to ensure that posts and profile was found within a user selector, but avoid remapping their selectors.