Preserving Class Methods during Deserialization in Angular 2

Question

Preserving Class Methods during Deserialization in Angular 2

Imagine I have a class called Foo:

export class Foo {
    name: string;

    printName(): void {
        console.log(this.name);
    } 
}

The issue arises when my FooService extracts a Foo object from the backend as JSON and converts it into a Foo instance, which doesn't include the printName() method since it's not part of the JSON object.

How can I handle this situation within an Angular 2 framework? Should I create separate methods outside the class that take a Foo object as an argument?

Unlike in Java where DTOs can contain methods, Angular 2 presents unique challenges in working with JSON objects and TypeScript classes.

json angular typescript

Answer 1

Answer №1

Typically, when transferring an object over HTTP, you only send the values and not a class instance. You will need to instantiate the class yourself.

export class Foo {

    constructor(name: string) {}
    printName(): void {
        console.log(this.name);
    } 
}


// Here is an example of deserialized data received from Angular
let data = { name: 'John' };

let foo: Foo = new Foo(data.name);

If helpful, consider creating interfaces for the server data and passing them into the constructor of the Foo class.

Note: TypeScript does not support type casting. So if you try something like

let foo: Foo = <Foo> data;

It is a type assertion where you are simply informing the compiler that data should be treated as type Foo without actually changing the data object itself.

Answer 2

Typically, when transferring an object over HTTP, you only send the values and not a class instance. You will need to instantiate the class yourself.

export class Foo {

    constructor(name: string) {}
    printName(): void {
        console.log(this.name);
    } 
}


// Here is an example of deserialized data received from Angular
let data = { name: 'John' };

let foo: Foo = new Foo(data.name);

If helpful, consider creating interfaces for the server data and passing them into the constructor of the Foo class.

Note: TypeScript does not support type casting. So if you try something like

let foo: Foo = <Foo> data;

It is a type assertion where you are simply informing the compiler that data should be treated as type Foo without actually changing the data object itself.

Preserving Class Methods during Deserialization in Angular 2

Answer №1

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