public-fields

public-fields

A module that allows transform class to object with public fields and conditional fields

Installation

You can install this module via npm:

npm install public-fields --save

or via yarn:

yarn add public-fields

Usage

Basic usage

To declare public field you need to use decorator @PublicField() before field:

class Test {
  @PublicField()
  somePublicField: string = 'hello world';

  somePrivateField: string = 'bye world';
}

And transform object:

const test = new Test();

const result = extractPublicFields(test);
console.log(result); // => { somePublicField: 'hello world' }

Conditions

There are situations where field will be public only if some condition is true. For this, you can use options.condition in decorator options and pass condition result to args of extractPublicFields:

class Test {
  @PublicField({ condition: 'isMySecretField' })
  someSecretField: string = 'very secret';

  @PublicField()
  somePublicField: string = 'hello world';

  somePrivateField: string = 'bye world';
}

const test = new Test();

const result1 = extractPublicFields(test);
console.log(result1); // => { somePublicField: 'hello world' }

const result2 = extractPublicFields(test, { isMySecretField: true });
console.log(result1); // => { somePublicField: 'hello world', someSecretField: 'very secret' }

Classes in class

There are an example of working with classes in class:

class Test2 {
    @PublicField()
    somePublicField2: string = 'hello world 2';

    @PublicField({ condition: 'isMySecretField' })
    someSecretField2: string = 'very secret 2';
}

class Test {
  @PublicField({ condition: 'isMySecretField' })
  someSecretField: string = 'very secret';

  @PublicField()
  somePublicField: string = 'hello world';

  @PublicField()
  testField: Test = new Test();

  somePrivateField: string = 'bye world';
}

const result1 = extractPublicFields(test);
console.log(result1); // => { somePublicField: 'hello world', testField: { somePublicField2: 'hello world 2' } }

const result2 = extractPublicFields(test, { isMySecretField: true });
console.log(result1); // => { somePublicField: 'hello world', someSecretField: 'very secret', testField: { somePublicField2: 'hello world 2', someSecretField2: 'very secret 2' } }

Why is it needed?

The idea of this module came to mind when it was necessary to describe the TypeORM model and at the same time return the document to the API user, but with defined fields. I imagine this description of the TypeORM model:

import { Entity, Column, PrimaryGeneratedColumn } from 'typeorm';
import { PublicField } from 'public-fields';

@Entity()
export class User {
  @PrimaryGeneratedColumn()
  @PublicField()
  id: number;

  @Column()
  @PublicField({ condition: 'isOwn' })
  money: number = 0;

  @Column()
  @PublicField({ condition: 'isOwn' })
  timestamp: number = Date.now();

  @Column()
  reportsCount: number = 0;
}