How to increase decimal precision on percentage format using Twig's Intl extension?

Question

I have a decimal number with 4 digits and a scale of 4. (Max is 0.9999 and min is 0.0000)

I'm using Twig and its intl extension. When I want to render a percent number, decimals are rounded.

{% set decimal = 0.0850 %}
{{ decimal|localizednumber('decimal','double','fr-fr') }} //WILL OUTPUT "0,085"
{{ decimal|localizednumber('decimal','double','zh-cn') }} //WILL OUTPUT "0.085"
{{ decimal|localizednumber('decimal','double','ar-bh') }} //WILL OUTPUT "٠٫٠٨٥"
{{ decimal|localizednumber('percent','double','fr-fr') }} //WILL OUTPUT "8 %"
{{ decimal|localizednumber('percent','double','zh-cn') }} //WILL OUTPUT "8%"
{{ decimal|localizednumber('percent','double','ar-bh') }} //WILL OUTPUT "% ٨"

I would like to see 8,5 % in French, 8.5% in chinese and % ٨٫٥ in arabic.

I tried to add the double parameter, but it does not change the precision.

As I am using Symfony, I tried to declare 2 decimals in number format:

<!-- lang-yml -->
#config/twig.yaml
twig:
    #...
    number_format:
        decimals: 2

It seems that the Intl extension is overriding these settings.

I know that I can do something like

{{ (decimal*100)|localizednumber('decimal','double')}}% 

But the % symbol can be before the result in some languages, in French, there is a non-breaking space before the % symbol.

Do you see my error? Do you have a solution?

Pasquale

Answer 1

Can't be done directly with Twig Intl extension you are using.

It doesn't have a parameter to set the precision, it simply instantiate the NumberFormatter with the formatting style of your choice, and will use that to format() your value.

Check the code here.

---

There is another extension which does have more options: https://github.com/twigphp/intl-extra

With this one you can specify all the attributes supported by NumberFormatter, as shown here.

You would use it like this:

{% set decimal = 0.0850 %}
{{ decimal|format_number(style='percent', locale='fr', {min_fraction_digit: 1}) }}

---

Alternatively, you could write your own extension by leveraging on NumberFormatter.

The pattern that NumberFormatter::PERCENT uses by default is #,##0 %, which does not include decimal precision. You can define your own pattern following these rules so it does.

Or simply call to setAttribute(NumberFormatter::MIN_FRACTION_DIGITS, 1) to specify the the minimum number of decimal numbers you are interested in.

For example:

$formatter->setAttribute(NumberFormatter::MIN_FRACTION_DIGITS, 1);

The final implementation is up to you, and if you'd need to use it within a Twig template you'd have to create your own (official Symfony docs).

See more examples here.

Expertise

Thanks a lot for your answer. I already upvoted it, but I want to explore a last idea before accepting it. Because I see in source code that the localized_numberfunction is calling via an attribute the max number of digit getAttribute(NumberFormat::MAX_FRACTION_DIGITS). It seems that it is possible to set this global parameter. I will try to explore this last idea, but I think your answer is the best solution. – Pasquale

You are absolutely right, you could use setAttribute(). I'll update the answer to account for that. – Expertise

Thanks a lot, it is perfect. I have created my own extension by leveraging NumberFormatter and I now use my extension to autoselect the good language which could come from session or user preferences. This extension seems interesting, too. – Pasquale