Typescript is a lifesaver when it comes to handling JSON arrays with optional properties. Its assistance is unparalleled

Question

Typescript is a lifesaver when it comes to handling JSON arrays with optional properties. Its assistance is unparalleled

I am working with a typescript object that looks like this:

class myObj {
   public param1,
   public param2,
   public param3
}

In another object, I have an array of that same object

class otherObj {
   public arrayOfMyObj:myObj[]

   constructor(){
       this.arrayOfMyObj = [{param1: "value", param2: "value"}]
   }
}

However, when attempting to run this code, it throws an error because the first item in the JSON array does not exactly match myObj (it is missing param3). Could there be a way to make param3 optional or just skip checking for it altogether? Normally, I would create a new myObj and populate it accordingly. However, in this case, the JSON array is long and hard-coded.

arrays json typescript

Answer 1

Answer №1

Here is an example of how it might appear:

interface IMyObj {
   property1: string;
   property2: string;
   property3?: any;
}


class AnotherObject {
   public arrayofMyObjects: IMyObj[]

   constructor() {
       this.arrayOfMyObjects = [{ property1: "value", property2: "value" }]
   }
}

Note

All properties in a class are defaulted to public access.

It's recommended to specify variable types. Not specifying a type defaults to "any" which may lead to unexpected errors during type checking.

Answer 2

Here is an example of how it might appear:

interface IMyObj {
   property1: string;
   property2: string;
   property3?: any;
}


class AnotherObject {
   public arrayofMyObjects: IMyObj[]

   constructor() {
       this.arrayOfMyObjects = [{ property1: "value", property2: "value" }]
   }
}

Note

All properties in a class are defaulted to public access.

It's recommended to specify variable types. Not specifying a type defaults to "any" which may lead to unexpected errors during type checking.

Answer 3

Answer №2

If you're looking for a solution, consider checking out this helpful answer

Another approach involves utilizing Object.assign to expand a valid typed object by adding only the necessary property (excluding properties a and c in this example)
export class A {
    a:number=1;
    b:number;
    c:string;
    d:string; }

let validA:A = Object.assign(new A(),{
    b:3,
    d:'Lorem ipsum' 
}); 
I personally find this syntax easier to work with as it simplifies object initialization and eliminates the need to create an interface for each model in my application.

Additionally, it's beneficial to set default values in your class definition, even if they are not required in every instance.

An important point to note is that class methods are retained using this method (unlike when casting to {}).

Answer 4

If you're looking for a solution, consider checking out this helpful answer

Another approach involves utilizing Object.assign to expand a valid typed object by adding only the necessary property (excluding properties a and c in this example)
export class A {
    a:number=1;
    b:number;
    c:string;
    d:string; }

let validA:A = Object.assign(new A(),{
    b:3,
    d:'Lorem ipsum' 
}); 
I personally find this syntax easier to work with as it simplifies object initialization and eliminates the need to create an interface for each model in my application.

Additionally, it's beneficial to set default values in your class definition, even if they are not required in every instance.

An important point to note is that class methods are retained using this method (unlike when casting to {}).

Typescript is a lifesaver when it comes to handling JSON arrays with optional properties. Its assistance is unparalleled

Answer №1

Note

Answer №2

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