Go模板:无法评估类型Y的字段X(X不是Y的一部分，但停留在{{range}}循环中) [英] Go template: can't evaluate field X in type Y (X not part of Y but stuck in a {{range}} loop)

问题描述

在此处回答类似问题，但我认为这不能解决我的问题.

Similar question answered here, but I don't think it solves my problem.

假设您具有以下结构:

type User struct {
    Username string
    Password []byte
    Email string
    ...
}

此外，URL具有这样的结构:example.com/en/users，其中"en"是将被传递到模板中的URL参数，如下所示:

Moreover, the URL hasa structure like this: example.com/en/users, where "en" is a URL param that will be passed into the template like this:

renderer.HTML(w, http.StatusOK, "users/index", map[string]interface{}{
  "lang":  chi.URLParam(r, "lang"),
  "users": users})

在HTML模板中，我有以下内容:

And in the HTML template I have the following:

{{ range .users }}
  <form action="/{{ .lang }}/users" method="POST">
    <input type="text" name="Username" value="{{ .Username }}">
    <input type="text" name="Email" value="{{ .Email }}">
  </form>
{{ end }}

现在，问题在于，由于{{ .lang }}不是User结构的一部分，所以我得到了错误..那么如何在{{ range .users }}内部访问{{ .lang }}?

Now, the problem is that because {{ .lang }} is not a part of the User struct then I get the error.. so how can I access {{ .lang }} inside {{ range .users }}?

推荐答案

点(.)的内容在调用range后分配给$，因此您可以使用$访问(播放中):

The contents of dot (.) are assigned to $ after invocation of range, so you can use $ to access lang (on play):

{{ range .users }}
  <form action="/{{ $.lang }}/users" method="POST">
    <input type="text" name="Username" value="{{ .Username }}">
    <input type="text" name="Email" value="{{ .Email }}">
  </form>
{{ end }}

此处:

执行开始时，将$设置为传递给Execute的数据参数，即dot的起始值.

When execution begins, $ is set to the data argument passed to Execute, that is, to the starting value of dot.

如果使用的是嵌套范围，则始终可以使用with语句或变量赋值语句回退以将点分配给其他对象.参见其他答案.

If you are using nested ranges, you can always fall back to assign dot to something else using the with statement or variable assignment statements. See the other answer for that.

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