将JSON转换为TypeScript对象的最佳方法是什么？

Question

I've JSON string

const json = '{ "first_name": "John", "last_name": "Doe"}';

and a class User

class User {

  constructor(
    public first_name: string,
    public last_name: string
  ) {
  }

  public getFullName = (): string => {
    return this.first_name + ' ' + this.last_name;
  };
}

and when I try this

const user: User = JSON.parse(json);

console.log(user.first_name); // Works, prints "John"
console.log(user.last_name); // Works, prints "Doe"
console.log(user.getFullName()); //Error: TypeError: user.getFullName is not a function

I know the error happened, because JSON.parse simply matched the User type but not methods in it.

So to fix this, I wrote a fromJSON static method in User class to parse manually,

public static fromJSON = (json: string): User => {
    const jsonObject = JSON.parse(json);
    return new User(
      jsonObject.first_name,
      jsonObject.last_name
    );
};

So these are my questions

1. Is this a perfect solution ?
2. Is there any better solution than this ?
3. Is there any built-in solution for this in TypeScript ?

Answer 1

It's a decent solution. A better one would be to use Object.assign so as to not have to write all the assignments as this ca get out of hand if there are many properties, but either will work fine.

class User {

    public first_name!: string;
    public last_name!: string;
    constructor(data: Partial<User>) {
        Object.assign(this, data);
    }

    public getFullName (): string {
        return this.first_name + ' ' + this.last_name;
    };

    public static fromJSON = (json: string): User => {
        const jsonObject = JSON.parse(json);
        return new User(jsonObject);
    };  
}

There is no buil-in solution for this in typescript, Object.assign is the closest to it. You might consider changing the constructor dynamically as detailed here , that will convert the object to an instance of the class but will not necessarily perform better.