@newtral/class-transformer NPM

@newtral/class-transformer

Install

npm install @newtral/class-transformer class-transformer

Usage

@Default(defaultValue)

Provide a default value when the value is not present or it is undefined

import { Default } from '@newtral/class-transformer';
import { plainToClass } from 'class-transformer';

class Client {
  @Default('http://localhost:3000') // Or using a function @Default(() => 'http://localhost:3000')
  baseUrl: string;
}

const client = plainToClass(Client, {});
console.log(client.baseUrl); // 'http://localhost:3000'

const client = plainToClass(Client, { baseUrl: 'https://example.com' });
console.log(client.baseUrl); // 'https://example.com'

@ToArray(defaultValue)

Transform the property into an array. When the value is undefined there is not action. When the value is not an array it gets transformer into an array of one element. This could be useful when obtaining multiple query string values but the user only selects one item.

import { ToArray } from '@newtral/class-transformer';
import { plainToClass } from 'class-transformer';

class User {
  @ToArray()
  postIds: string[];
}

const client = plainToClass(User, { postIds: '12345' });
console.log(client.postIds); // ['2345']

@ToBoolean()

A default value can be provided due how to this bug in class-transformer. It uses the yn package for transformations

import { ToBoolean } from '@newtral/class-transformer';
import { plainToClass } from 'class-transformer';

class User {
  @ToBoolean({ default: false })
  isAdmin: boolean;
}

const user = plainToClass(User, { isAdmin: 'true' });
console.log(user.isAdmin); // true

@ToObjectId()

Transform an object id value to string an vice versa using the following conventions:

It will do nothing if the value is undefined
plain to class or class to class: If the object is a string it uses new ObjectId(value)
class to plain: converts the object id to it string representation

import { ToObjectId } from '@newtral/class-transformer';
import { ObjectId } from 'bson';
import { classToPlain, plainToClass } from 'class-transformer';

class User {
  @ToObjectId()
  _id: ObjectId;
}

const user = plainToClass(User, { _id: '5ed116e81723fcd8ed3d230b' });
console.log(user._id instanceof ObjectId); // true

const plainUser = classToPlain(user);
console.log(typeof user._id); // 'string'
console.log(user._id); // '5ed116e81723fcd8ed3d230b'