need-some-json.js

need-some is a collection of small yet useful functions. The json package provides typed json binding

Installation

Simply install as dependency

npm install @need-some/json --save

Usage

Use JsonConverter to translate json strings to typed objects(using the concrete classes) and back. The Json annotations cannot type check its annotated members, so it must be defined carefully.

Create a converter

class MyClass {
	id: number
}

const converter = new JsonConverter(MyClass);

const json = converter.marshal(obj);

const obj2 = converter.unmarshal(json);

JsonMarshaller

Instance to convert objects to json strings.

JsonMarshaller

Instance to convert json strings to objects.

JsonConverter

Bot Marshaller and Unmarshaller

Binding annotations

Force Classname

If running minified code, the marshaller is not able to find the class name and adds members to random class descriptors. To mitigate or allow multiple classes to be named identical, add a static member to the class:

static __JSON__CLASSNAME = 'SomeReallyUniqueName';

@JsonElement

Simple annotation denoting an element to be a json element. Optional, if no renaming of the member is done. and other json annotations are present.

@JsonElement()
id: number;

@JsonElement('nameInJson')
nameInObj: string;

@JsonNull

Define member to be nullable. The json representation is the "null" json value

@JsonNull()
nember: string | null;

@JsonOptional

Define member to be optional. The json will not contain the key if the object representation is undefined.

@JsonOptional()
nember?: string;

@JsonChild

Define class of member to delegate to new JsonConverter for the given class.

@JsonChild(ChildClass)
child: ChildClass;

@JsonEnum

Define enum type of member. The Json representation is the string key.

@JsonEnum(Enum)
nember: Enum;

@JsonDiscriminator

Mark member to be the discriminator member of a super class. Should be used on string members. Note that the type can be private to the parent class and will be set when performing a conversion

@JsonDiscriminator()
private type: string

@JsonDiscriminatorValue

Set value to identify subclass in the discriminator member

@JsonDiscriminatorValue('CAR')
class Car extends Vehicle

@JsonTypes

List all subclasses of the given class. Given as function, so declaration before the actual child classes is possible

@JsonTypes(()=>[Car, Motorbike])
class Vehicle

@JsonTransform

Declare a converter to be used when processing the member. A converter has a marshal and an unmarshal function. The parameter may be a converter instance, converter constructor or a converter factory or even a converter factory constructor

@JsonTransform(DateConverter)
date:Date;