Jan Nielsen Jan Nielsen - 5 days ago 5
TypeScript Question

Handling dollars in Angular 2 Material Slider

I have a form in my Angular 2 Material application with, among other things, a price field modeled as a slider with a maximum, minimum, and step:

<md-input type="range"
[min]="minimumPrice"
[max]="maximumPrice"
[step]="priceTick"
class="slider">


Prices are modeled in cents (i.e. with no fractions), but the front-end should display prices in dollars, e.g., a price of
12345
cents with a maximum of
50000
cents, a minimum of
0
cents, and a step of
5
cents looks like this now:

12345
0 |---------*---------------| 50000

in steps of 5


but it should be displayed in terms of dollars:

$123.45
$0.00 |---------*---------------| $500.00

in steps of $0.05


The form and slider work when displayed cents, but how can I get the slider to behave and display correctly with values in dollars?

The back-end price model is a
long
which is sent to the front-end as a
long
value (i.e., with no fractions) but I'm willing to change what I send to the front-end to simplify handling, if need be. So, the general question is: what's the simplest way to get
md-input
to display dollars correctly, and behave correctly?

Answer

Without being entirely familiar with Angular2 Material I would venture using the CurrencyPipe combined with a template variable for the slider if you're eschewing model binding:

<md-input type="range" name="slider"
  [min]="minimumPrice"
  [max]="maximumPrice"
  [step]="priceTick"
  #slider
  class="slider" [placeholder]="slider.value | customCurrency">
    <span md-prefix>{{slider.min | customCurrency}}</span>
    <span md-suffix>{{slider.max | customCurrency}}</span>
</md-input>

The layout is probably incorrect but that is the gist of it, and you can muck around with this Plunker http://plnkr.co/edit/Fj3hDJmwRD4SvzlKu6R6?p=preview

Here's a very simple custom extension of the CurrencyPipe to remove the /100 and set formatting:

custom-currency.pipe.ts

import {Pipe, PipeTransform} from '@angular/core';
import {CurrencyPipe} from '@angular/common';

@Pipe({
    name: "customCurrency"
})
export class CustomCurrencyPipe implements PipeTransform {

    constructor(private currencyPipe: CurrencyPipe) {}

    transform(value: any): string {
      return this.currencyPipe.transform(value / 100, 'USD', true);
    }
}

module.ts

import {CustomCurrencyPipe} from "[location]/custom-currency.pipe";
import {CurrencyPipe} from "@angular/common";

@NgModule({<...>, declarations: [<...>, CustomCurrencyPipe], providers: [<...>, CurrencyPipe]})
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