如何将标量树枝过滤器映射到数组 [英] How to map scalar twig filter to array

问题描述

我有一个简单的浮点数组.我需要将其显示为逗号分隔的字符串.

I have a simple array of floats. And I need to show it as comma separated string.

{{ arr|join(', ') }}

由于准确性太低而无法解决问题.

is bad solution because of excessive insignificant accuracy.

{% for val in arr %}
    {{val|number_format(2)}},
{% endfor %}

不好，因为结尾有逗号.

is bad because of extra comma at the end.

我想做这样的事情:

{{ arr|map(number_format(3))|join(', ') }}

但是我没有找到过滤器map或类似的过滤器Twig. ?我不知道如何实现这种过滤器.

but I have not found filter map or similar filter it Twig. Аnd I don't know how to implement such filter.

推荐答案

快速解答(TL; DR)

• 此问题与高阶函数有关
  • 地图是高阶函数
  • (请参见例如) https://en.wikipedia.org/wiki/Map_ (高级功能)
  • (请参见例如) https://en.wikipedia.org/wiki/Higher-order_function

  Quick Answer (TL;DR)

  • This question relates to higher-order functions
    • Map is a higher-order function
    • (see eg) https://en.wikipedia.org/wiki/Map_(higher-order_function)
    • (see eg) https://en.wikipedia.org/wiki/Higher-order_function
    • Twig 2.x(Wed 2017-02-08的最新版本)
    • 场景::DeveloperGarricSugas希望将高阶函数应用于Twig变量
      • 高阶函数允许对任何Twig变量进行各种变换
      • Scenario: DeveloperGarricSugas wishes to apply higher-order function(s) to a Twig variable
        • Higher order functions allow any of various transformations on any Twig variable
        • (请参见例如) https://github.com/dpolac/twig-lambda
        • DeveloperGarricSugas以顺序索引数组开头
        • 从BEFORE转换为AFTER(大写首字母)
        • DeveloperGarricSugas starts with a sequentially-indexed array
        • transform from BEFORE into AFTER (uppercase first letter)

        
        {%- set mylist = ['alpha','bravo','charlie','delta','echo']  -%}
        
        BEFORE: 
        ['alpha','bravo','charlie','delta','echo']
        
        AFTER: 
        ['Alpha','Bravo','Charlie','Delta','Echo']
        
        

        解决方案

        
        {%- set mylist = mylist|map(=> _|capitalize)  -%}    
        

        陷阱

        • Twig高阶函数的有限支持来自插件库
        • 上述解决方案不适用于本地Twig

        Pitfalls

        • Twig higher-order functions limited support comes from addon-libraries
        • The above solution does not work with native Twig
        • https://twigfiddle.com/rsl89m
        • https://github.com/dpolac/twig-lambda
        • https://twigfiddle.com/rsl89m
        • https://github.com/dpolac/twig-lambda

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