您无法像这样到达NestedStructID字段，因为{{range}}操作将每次迭代中的管线(点.)设置为当前元素.

You can't reach the NestedStructID field like that because the {{range}} action sets the pipeline (the dot .) in each iteration to the current element.

您可以使用$，该参数设置为传递给Template.Execute()的数据参数；因此，如果您传递值NestedStruct，则可以使用$.NestedStructID.

You may use the $ which is set to the data argument passed to Template.Execute(); so if you pass a value of NestedStruct, you can use $.NestedStructID.

例如:

func main() {
    t := template.Must(template.New("").Parse(x))

    ns := NestedStruct{
        NestedStructID: "nsid",
        Foos: []Foo{
            {"f1-1", "f2-1"},
            {"f1-2", "f2-2"},
        },
    }
    fmt.Println(t.Execute(os.Stdout, ns))
}

const x = `{{range .Foos}}{ source: '{{.Field1}}', target: '{{$.NestedStructID}}' }
{{end}}`

输出(在游乐场上尝试):

{ source: 'f1-1', target: 'nsid' }
{ source: 'f1-2', target: 'nsid' }
<nil>

此文档记录在 text/template :

This is documented in text/template:

执行开始时，将$设置为传递给Execute的data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.