JSON to Javascript Class
Solution 1
Just assign to an instance:
static from(json){
return Object.assign(new Student(), json);
}
So you can do:
const student = Student.from({ name: "whatever" });
Or make it an instance method and leave away the assignemnt:
applyData(json) {
Object.assign(this, json);
}
So you can:
const student = new Student;
student.applyData({ name: "whatever" });
It could also be part of the constructor:
constructor(options = {}) {
Object.assign(this, options);
}
Then you could do:
const student = new Student({ name: "whatever" });
And also, if a property name has changed, let's say: lastname became LastName, I will have to fix it?
Yes you will have to fix that.
Solution 2
There is no way in javascript to deserialize json into classes. So I wrote a library ts-serializable that solves this problem.
import { jsonProperty, Serializable } from "ts-serializable";
export class User extends Serializable {
@jsonProperty(String)
public firstName: string = ''; // default value necessarily
@jsonProperty(String, void 0)
public lastName?: string = void 0; // default value necessarily
@jsonProperty(Date)
public birthdate: Date = new Date(); // default value necessarily
public getFullName(): string {
return [
this.firstName,
this.lastName
].join(' ');
}
public getAge(): number {
return new Date().getFullYear() - this.birthdate.getFullYear();
}
}
const user: User = new User().fromJSON(json);
user.getFullName(); // work fine and return string
user.getAge(); // work fine and return number
// or
const user: User = User.fromJSON(json);
user.getFullName(); // work fine and return string
user.getAge(); // work fine and return number
The library also checks types during deserialization.
TSR
Updated on June 24, 2021Comments
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TSR almost 3 years
I have a http request that gets this Json object from a nosql database:
let jsonBody = { birthday : 1997, firstname: 'foo', lastname:'bar' }
Then I want to load this information into the Student model:
class Student{ constructor(){ } getFullname(){ return this.lastname+' '+this.firstname } getApproxAge(){ return 2018- this.birthday } }
Normally, I would add this method to this class:
fromJson(json){ this.studentId = json.studentId; this.birthday = json.birthday; this.firstname = json.firstname; this.lastname = json.lastname; }
I would use it as follow:
let student = new Student() student.fromJson(jsonBody) console.log(student.getFullname()) console.log(student.getApproxAge())
This works fine but my problem is I have: 100 proprieties in reality. Will I have to write all proprities one by one in the fromJson method?
And also, if a propriety name has change, let's say: lastname became LastName, I will have to fix it?
Is there a simpler way to just assign these values to the object student dynamically but keep all of its methods??
Something like this:
fromJson(json){ this = Object.assign(this, json) //THIS IS NOT WORKING }
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tensor over 2 yearsthis answer is correct but still it doesn't help me with code completion :(