Transform `<option value="1: '2'"></option>` to <option value="2"></option> in Angular2 <select multiple>

gistfile1.txt

import {Directive, ElementRef} from '@angular/core';
import {Input} from '@angular/core';

@Directive({
    selector: '[multipleNormalize]',
})

export class MultipleNormalizeDirective {

    @Input('multipleNormalize') model:any;

    constructor(private elementRef:ElementRef) {
    }

    ngOnInit(): void {
        this.elementRef.nativeElement.value = this.model;
    }

}