@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'

Development

The project use husky and lint-staged for linting and fixing possible errors on source code before commit

Git hooks scripts are installed after running npm install the first time

npm run build:commonjs

Compile typescript files from the src folder inside the lib folder

npm run build:esm

Compile typescript files from the src folder inside the esm folder using es modules

npm run build

Concurrently run both build:commonjs and build:esm

npm run clean

Remove the following directories/files

• lib
• esm
• reports

npm test

Run tests files inside the tests folder that matches the following patterns. Exit with code > 0 on error

• *.test.ts
• *.spec.ts

npm run cover

The same as npm test and generates coverages reports in reports/coverage. Exit with code > 0 on error

npm run lint

Check eslint errors according to .eslintrc

npm run lint:fix

Run npm run lint applying fixes and run prettier on every typescript file

npm run health

Check for:

• Build errors
• Tests failures
• Lint errors

npm run ci

Run test and generate every possible report. Do not exit with error code > 0 if the tests fail. It generates a report file instead

• reports/lint-checkstyle.xml Lint report in chackstyle format
• reports/test-results.xml Test report in xUnit format
• reports/coverage/clover.xml Coverage report in clover format
• reports/coverage/cobertura-coverage.xml Coverage report in cobertura format
• reports/coverage/lcov.info Coverage report in lcov
• reports/coverage/index.html Coverage report in html