Typescript JSON to Class with "es5"

Question

What is the best/common way to cast a JSON into a class in Typescript with ES5 (no Object.assign()).

e.g.

export class Lesson{
 name:string;
 teacher:Teacher;
 date:Date;
 scholars:Array<string>; //or string[] ... I dont care
}

The JSON would look like:

{
 name:"LessonName",
 teacher:{name:"masterT", age:120},
 date:12345678912
 scholars:["Jim","Bob","Jimbo"]
}

In Typescript I can cast the JSON to a Object and even assign it straight to a Lesson object (!-horrible behaviour, but thats JS-!)

But the object don't have any methods for example.

e.g. So lesson.date.getTime() won't work.

So how to handle that correctly?

Possible duplicate of How do I initialize a typescript object with a JSON object — jcalz
– jcalz, Commented Sep 1, 2017 at 17:27
This is the job for the constructor of a class. This way you can cast the date field into a Date object etc so you can do new Lesson(attributes) — Fotis
– Fotis, Commented Sep 1, 2017 at 17:28

Christof Hullaert · Accepted Answer · 2017-09-01 17:23:29Z

0

Try

// first declare variable
var lesson: Lesson;

// and then assign that
lesson={
 name:"LessonName",
 teacher:{name:"masterT", age:120},
 date:12345678912
 scholars:["Jim","Bob","Jimbo"]
}

But the problem is that you want to put only a value in an object.

edited Sep 1, 2017 at 17:23

answered Sep 1, 2017 at 17:04

Christof Hullaert

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6 Comments

jcalz Over a year ago

This is not valid TypeScript, nor does it answer the question properly (for instance, the date property is not a Date object.)

jcalz Over a year ago

But lesson is still not an instance of the Lesson class. You need to do something like lesson = new Lesson(), and then start setting properties. And date is still not a Date. Sorry, but this is not a proper answer.

Christof Hullaert Over a year ago

you can also see there, same problem.

Christof Hullaert Over a year ago

stackoverflow.com/questions/40421100/…

Christof Hullaert Over a year ago

You can also use this library npmjs.com/package/serializer.ts

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