模板范围内的最后一项 [英] Last item in a template range

问题描述

给出模板:

{{range $i, $e := .SomeField}}
        {{if $i}}, {{end}}
        $e.TheString
{{end}}

这可以输出:

one, two, three

但是，如果我想输出:

one, two, and three

我需要知道上面范围内的最后一个元素.

I'd need to know which is the last element in the range above.

我可以设置一个变量，该变量保存数组 .SomeField 的长度，但是始终为3，并且上面的 $ i 值将永远变为2.而且，根据我所见，您无法在模板中执行算术运算.

I can set a variable that holds the length of the array .SomeField, but that will always be 3, and the $i value above will only ever get to 2. And you can't perform arithmetic in templates from what I've seen.

是否正在检测模板范围内的最后一个值?干杯.

Is detecting the last value in a template range possible? Cheers.

推荐答案

这可能不是最优雅的解决方案，但却是我能找到的最好的解决方案:

This is probably not the most elegant solution but it's the best I could find:

http://play.golang.org/p/MT91mLqk1s

package main

import (
    "os"
    "reflect"
    "text/template"
)

var fns = template.FuncMap{
    "last": func(x int, a interface{}) bool {
        return x == reflect.ValueOf(a).Len() - 1
    },
}


func main() {
    t := template.Must(template.New("abc").Funcs(fns).Parse(`{{range  $i, $e := .}}{{if $i}}, {{end}}{{if last $i $}}and {{end}}{{$e}}{{end}}.`))
    a := []string{"one", "two", "three"}
    t.Execute(os.Stdout, a)
}

注意:您还可以使用 len 函数(贷记给Russ Cox)在不反射的情况下执行此操作: http://play.golang.org/p/V94BPN0uKD

Note: You can also do it without reflect using the len function (credit to Russ Cox): http://play.golang.org/p/V94BPN0uKD

c.f.

• https://groups.google.com/forum/#！topic/golang-nuts/yRXHSCjVAcM
• https://groups.google.com/论坛/#！msg/golang-nuts/XBScetK-guk/Bh7ZFz6R3wQJ
• https://groups.google.com/forum/#！topic/golang-nuts/mqRbR7AFJj0

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