Develop a custom extension method for FormControl in Angular version 8

Question

Develop a custom extension method for FormControl in Angular version 8

I am looking to develop an extension for FormGroup that will convert Persian dates to Gregorian dates. Here is the code I have written for the extension:

import { FormControl } from '@angular/forms'

export { }

declare global {
    interface FormControl {
        ToMiladidate(date: Date): string;
    }
}

FormControl.prototype.ToMiladidate = function (date: Date): string {
    if (!date)
        return this;
    return new Date(date).toISOString();
}

However, I encountered an error on this line:

FormControl.prototype.ToMiladidate

The error message states:

Property 'ToMiladidate' does not exist on type 'FormControl'

What could be causing this issue? How can I resolve it?

javascript angular typescript

Answer 1

Answer №1

If you're still searching for the right answer, look no further:

declare module '@angular/forms' {


interface AbstractControl {
    ToMiladidate(date: Date): string;
  }
}

AbstractControl.prototype.ToMiladidate = function (date: Date): string {
  if (!date)
    return this;
  return new Date(date).toISOString();
}

To solve this issue, make sure to switch from using FormControl to AbstractFormControl and define your module as @angular/forms. If you've defined your prototype in a separate file, remember to import it into app.module.ts at the top of imports:

import './form.prototype';

Answer 2

If you're still searching for the right answer, look no further:

declare module '@angular/forms' {


interface AbstractControl {
    ToMiladidate(date: Date): string;
  }
}

AbstractControl.prototype.ToMiladidate = function (date: Date): string {
  if (!date)
    return this;
  return new Date(date).toISOString();
}

To solve this issue, make sure to switch from using FormControl to AbstractFormControl and define your module as @angular/forms. If you've defined your prototype in a separate file, remember to import it into app.module.ts at the top of imports:

import './form.prototype';

Develop a custom extension method for FormControl in Angular version 8

Answer №1

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