TypeSerializer

Serializer / deserializer of javascript objects

Table of contents

• Installation
• Decorators
  • Exclude
  • Expose
  • Name
  • Groups
  • Version
  • Type
• Deep Objects
• Custom Deserializer
• Custom Serializer

Installation

1. Install using npm:

 $ npm install typeserializer --save

2. You also need to install reflect-metadata shim:

 $ npm install reflect-metadata --save

3. Import reflect-metadata in a global place of your app (for ex. index.ts):

import 'reflect-metadata';

Decorators

Exclude

While using the default manual exclude you only need to decorate the properties you like to exclude with @Exclude.
This will cause the property to be EXCLUDED from the response.

 import {serialize, Exclude} from 'typeserializer';

 class User {
 
   name = 'dan';
   
   @Exclude()
   password = '123456';
 }
 
 const user = new User();
 console.log(serialize(user)); // prints: '{ name: 'dan' }'

Expose

Using all as the exclusion strategy will exclude all properties except for those marked as @Expose().

 import {serialize, Expose, Strategy, ExclusionPolicy} from 'typeserializer';

 @Strategy(ExclusionPolicy.ALL) // <-- This is Required!
 class User {
   @Expose()
   name = 'dan';
   
   password = '123456';
 }
 
 const user = new User();
 console.log(serialize(user)); // prints: '{ name: 'dan' }'

Expose - Dynamic Exclusion

If you would like to use a dynamic approach as an exclusion strategy, you can also make use of the dynamic exclusion capability.

import {Strategy, Expose, ExclusionPolicy, serialize} from 'typeserializer';

 function validator(object: any, propertyKey: string) {
   return object[propertyKey] > 5;
 }
 
@Strategy(ExclusionPolicy.ALL)
 class Foo {
 
   @Expose(validator)
   prop = 1;
 
   @Expose(validator)
   prop2 = 10;
 
   @Expose(validator)
   prop3 = 8;
 }
 
 const foo = new Foo();
 console.log(serialize(foo)); // prints: '{ prop2: 10, prop3: 8 }'

Name

Changing name of a selected property is supported by using the @Name decorator.

 import {serialize, Name} from 'typeserializer';

 class User {
 
   @Name('name')
   myName = 'dan';
   
 }
 
 const user = new User();
 console.log(serialize(user)); // prints: '{ name: 'dan' }'

Groups

You can expose different properties by using the @Groups annotation.

 import {Strategy, Expose, ExclusionPolicy, Groups, serialize} from 'typeserializer';

 @Strategy(ExclusionPolicy.ALL)
 class User {
 
   @Expose()
   @Groups(['user-account'])
   username = 'Dan';
 
   @Expose()
   @Groups(['user-details'])
   age = 28;
 
   password = 'foo';
 }
 
 const user = new User();
 console.log(serialize(user)); // prints: '{ username: 'Dan', age: 28 }'
 console.log(serialize(user, ['user-account'])); // prints: '{ username: 'Dan' }'
 console.log(serialize(user, ['user-details'])); // prints: '{ age: 28 }'
 console.log(serialize(user, ['user-account', 'user-details'])); // prints: '{ username: 'Dan', age: 28 }'

Deep Objects

TypeSerializer can also serialize objects deeply.

 import {Strategy, Expose, ExclusionPolicy, Groups, serialize} from 'typeserializer';

@Strategy(ExclusionPolicy.ALL)
class UserDetails {

  @Expose()
  @Groups(['name'])
  firstName = 'Dan';

  @Expose()
  @Groups(['name'])
  lastName = 'Revah';

  @Expose()
  @Groups(['other'])
  age = 28; 
}

@Strategy(ExclusionPolicy.ALL)
 class User {
 
   @Expose()
   @Groups(['user-account'])
   username = 'Dan';
 
   @Expose()
   @Groups(['user-details'])
   details = new UserDetails();
 
   password = 'foo';
 }
 
 const user = new User();
 console.log(serialize(user, ['user-details'])); // prints: { details: { firstName: 'Dan', lastName: 'Revah', age: 28 } }
 console.log(serialize(user, ['user-details', 'name'])); // prints: { details: { firstName: 'Dan', lastName: 'Revah' } }
 console.log(serialize(user, ['user-details', 'other'])); // prints: { details: { age: 28 } }

Version

You can also serialize a property by version number with @Before & @After.

 import {Strategy, Expose, ExclusionPolicy, serialize, Before, After} from 'typeserializer';

@Strategy(ExclusionPolicy.ALL)
 class UserDetails {
 
   @Expose()
   @Before('1.2.0')
   firstName = 'Dan';
 
   @Expose()
   @Before('1.2.0')
   lastName = 'Revah';
 
   @Expose()
   @After('1.2.0')
   fullName = 'Dan Revah';
 }
 
 const user = new UserDetails();
 console.log(serialize(user)); // prints: '{ firstName: 'Dan', lastName: 'Revah', fullName: 'Dan Revah' }'
 
 console.log(serialize(user, [], '0.4.2')); // prints: '{ firstName: 'Dan', lastName: 'Revah' }'
 console.log(serialize(user, [], '1.1.9')); // prints: '{ firstName: 'Dan', lastName: 'Revah' }'
 
 console.log(serialize(user, [], '1.2.0')); // prints: '{ fullName: 'Dan Revah' }'
 console.log(serialize(user, [], '1.3.0')); // prints: '{ fullName: 'Dan Revah' }'

Type

TypeSerializer also contains a deserialize() method, to deserialize JSON to objects.

Since TypeScript doesn’t transpiles types, it is a requirement to add @Type annotation for the ‘complex’ type properties, including JavaScript’s Date.

This is very useful when you are getting a JSON string, and you know it’s of a certain type.

import {deserialize, Type} from 'typeserializer';

const fixtureSimple =
  '{"firstName":"Dan","lastName":"Revah","age":28,"isHere":true,"birthDate":"2018-07-15T05:35:03.000Z"}';
  
const fixtureChild = `{"child":${fixtureSimple}}`;
const fixtureChildren = `{"children":[${fixtureSimple}, ${fixtureSimple}]}`;

class Simple {
  firstName: string;
  lastName: string;
  age: number;
  isHere: boolean;

  @Type(Date)
  birthDate: Date;
  
  getFullName() {
    return `${this.firstName} ${this.lastName}`;
  }
}

class SimpleChild {
  @Type(Simple) 
  child: Simple;
}

class SimpleChildArr {
  @Type([Simple])  // You must wrap with '[]' when defining an array of a type.
  children: Simple[];
}

const simple: Simple = deserialize(fixtureSimple, Simple);

 console.log(simple); // Simple { firstName: "Dan", ... }
 console.log(simple.getFullName()); // Now you can even use class methods! -> Prints 'Dan Revah'. 
 

 console.log(deserialize(fixtureChild, SimpleChild)); // SimpleChild { child: Simple { firstName: "Dan", ... } }
 console.log(deserialize(fixtureChildren, SimpleChildArr)); // SimpleChildArr { children: [Simple { ... }, Simple { ... }] }

Custom Deserializer

It’s also possible to use a custom deserializer, in-case you have any ‘special’ types you want to handle.

For example you could deserialize to a Moment instance using the @Deserializer() annotation.

import {Deserializer, deserialize} from 'typeserializer';

const fixture = '{"date":"2012-12-21T00:00:00"}';

class Foo {
  @Deserializer((m: string): any => Moment(m))
  date: Moment;
  
  getDate() {
    return this.date.format('DD-MM-YYYY');  
  }
  
}

const foo: Foo = deserialize(fixture, Foo);

console.log(foo.getDate()); // '21-12-2012'

Custom Serializer

It’s also possible to use a custom serializer, in-case you have any ‘special’ types you want to handle.

For example you could serialize from a Moment instance using the @Serializer() annotation.

import {Serializer, serialize} from 'typeserializer';

class Bar {
  @Serializer((m: Moment): any => m.format('DD-MM-YYYY'))
  date: Moment;
}

const bar: Bar = new Bar();

bar.date = Moment('2012-12-21T00:00:00');

console.log(serialize(bar)); // {"date":"21-12-2012"}

And ofcourse this can be combined with the previous custom Deserializer:

import {Serializer, serialize} from 'typeserializer';

class Bar {
  @Deserializer((m: string): any => Moment(m))
  @Serializer((m: Moment): any => m.format('DD-MM-YYYY'))
  date: Moment;
}

const bar: Bar = new Bar();
bar.date = Moment('2012-12-21T00:00:00');
const json = serialize(bar);
console.log(json); // {"date":"21-12-2012"}

const bar2: Bar = deserialize(json, Bar);
console.log(bar2.getDate()); // '21-12-2012'