How to tell angular (2) currency pipe to display a

问题:

The currency pipe should be smart enough to handle string, float, int, etc automatically.

if passed value is string or not int or float, it should do nothing and display the passed value as it is. And only display formatted value if it is int or float.

It was happening in angularJs but not happening in angular (2)

How to tell currency pipe to escape in case its string and do currency formatting if its a decimal value. I am expecting something like below.

Example

<div>Money:{{'xxx/vv/cc' | currency:'USD':true:'1.2-2'}}</div> should display xxx/vv/cc

<div>Money: {{''11.99'' | currency:'USD':true:'1.2-2'}}</div> should display $11.99 --$ symbol included.

But its not happening. Error I am getting is caused by: Invalid argument 'Included' for pipe 'CurrencyPipe'

I think it was happening by default in angularjs but in angular2 its not happening by defalut.

回答1:

The manual explicitly states that it accepts a numeric expression and nothing else:

number_expression | currency[:currencyCode[:symbolDisplay[:digitInfo]]]

The pipe is really simple and can be extended and used instead of CurrencyPipe to conform to the expected behaviour:

const _NUMBER_FORMAT_REGEXP = /^(\d+)?\.((\d+)(-(\d+))?)?$/;

@Pipe({name: 'currency'})
export class LooseCurrencyPipe extends CurrencyPipe {
  transform(value: any, currencyCode: string, symbolDisplay: boolean, digits: string): string {
    if (typeof value === 'number' || _NUMBER_FORMAT_REGEXP.test(value)) {
      return super.transform(value, currencyCode, symbolDisplay, digits);
    } else {
      return value;
    }
  }
}

To create a new pipe with different name, CurrencyPipe may be injected into custom pipe:

@Pipe({name: 'looseCurrency'})
export class LooseCurrencyPipe implements PipeTransform {
  constructor(private _currencyPipe: CurrencyPipe) {}

  transform(value: any, currencyCode: string, symbolDisplay: boolean, digits: string): string {
    if (typeof value === 'number' || _NUMBER_FORMAT_REGEXP.test(value)) {
      return this._currencyPipe.transform(value, currencyCode, symbolDisplay, digits);
    } else {
      return value;
    }
  }
}

In order for CurrencyPipe to be injected through DI, it should be additionally added to module providers:

declarations: [LooseCurrencyPipe, ...],
providers: [CurrencyPipe, ...],

回答2:

You can use the ternary operator a ? b : c to show b when a is truthy, but show c otherwise.

First have a function in your component that returns true when the value is a number.

component

isNumber(e) {return typeof e === 'number'}

Then use that to determine whether to send the value to the currency pipe or print it directly

template

<div>
    {{ isNumber(money) ? (money|currency:'USD':true:'1.2-2') : money }}  
</div>

live demo