Question

我不理解http://golang.org/pkg/text/template/

中的文档段落

- The name of a key of the data, which must be a map, preceded
  by a period, such as
    .Key
  The result is the map element value indexed by the key.
  Key invocations may be chained and combined with fields to any
  depth:
    .Field1.Key1.Field2.Key2
  Although the key must be an alphanumeric identifier, unlike with
  field names they do not need to start with an upper case letter.
  Keys can also be evaluated on variables, including chaining:
    $x.key1.key2

这是我的测试代码，但失败了。代码：http://play.golang.org/p/lbLJ4yoL2T。

var season = map[int]string{1: "spring", 2: "summer",              
        3: "autumn", 4: "winter"}                                  

func main() {                                                      
        const greeting = `Welcome, {{.Key}}`                       
        t := template.Must(template.New("greet").Parse(greeting))  
        err := t.Execute(os.Stdout, season)                        
        if err != nil {                                            
                fmt.Println(err)                                   
        }                                                          
}

输出

Welcome, template: greet:1:11: executing "greet" at <.Key>: can't evaluate field Key in type map[int]string

Answer 1

我假设“Key”是地图的键（如键/值）。此外，映射键不能是int，以便在模板中使用它。因此，而不是{{.Key}}尝试{{.a}}，而不是fork of your playground：

var season = map[string]string{"a": "spring", "b": "summer",              
        "c": "autumn", "d": "winter"}                                  

func main() {                                                      
        const greeting = `Welcome, {{.a}}`                       
        t := template.Must(template.New("greet").Parse(greeting))  
        err := t.Execute(os.Stdout, season)                        
        if err != nil {                                            
                fmt.Println(err)                                   
        }                                                          
}

输出：

Welcome, spring

如何在go文本/模板使用中使用.Key

1 个答案: