Typescript Array of Typed Classes

Question

I am new to to development overall, so please pardon my ignorance.I am trying to understand how to use Typescript classes to combine two arrays of a given class

Using the following example the ValidationError class consists of a property and an error message. The MyErrors class is an array of the ValidationError class. I have various modules that will return a MyErrors and want to then concatenate them into a single array of ValidationErrors

Ultimately I would like it to look something like the following:

let allErrors = new MyErrors

allErrors.add("property_a","there was an error with property a") // add an error in the main module

let module_a = returns a MyErrors array
let module_b = returns a MyErrors array

allErrors.addAll(module_a) // Add all errors returned from module_a to allErrors 
allErrors.addAll(module_b) // Add all errors returned from module_b to allErrors 
//allErrors should now be an array of ValidationError items the include the items from the main module, module_a and module_b

Below is my starting place:

export class ValidationError  {
    public property: string
    public error: string
    constructor(property: string, error: string){
        this.property = property;
        this.error = error;
    };  
}

export class MyErrors extends Array<ValidationError>{
    add(property: string,error: string) {
        let newError = new ValidationError(property,error);
        return this.push(newError);
    }
    addAll(errors: MyErrors) {
        return this.concat(errors); //MyErrors instance that concatenates to the declared instance
    }
}

Thank you for your help!

Keen · Accepted Answer · 2020-04-14 18:35:30Z

1

You could achieve what you want without extending Array at all.
The spread syntax allows you to call Array.push() with elements from another array.

const allErrors: ValidationError[] = [];

allErrors.push(new ValidationError("property", "error"));

const moduleA: ValidationError[] = [ /* ... */ ];
const moduleB: ValidationError[] = [ /* ... */ ];

// Here's the nice bit using the spread syntax
allErrors.push(...moduleA, ...moduleB);

answered Apr 14, 2020 at 18:35

Keen

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