dongshai8330
2018-03-25 06:41
浏览 415
已采纳

Golang从模板到模板传递多个值?

My City struct is like this:

type City struct {
    ID      int
    Name    string
    Regions []Region
}  

And Region struct is:

type Region struct {
    ID               int
    Name             string
    Shops            []Destination
    Masters          []Master
    EducationCenters []Destination
}

In main I try to do this:

tpl.ExecuteTemplate(resWriter,"cities.gohtml",CityWithSomeData)

Is it possible to do something like this inside template?

{{range .}}
        {{$city:=.Name}}
            {{range .Regions}}
                      {{$region:=.Name}}
                      {{template "data" .Shops $city $region}}
            {{end}}
{{end}}

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我的 City 结构如下:

 类型城市结构{
 ID int 
名称字符串
地区[] Region 
} 
   
 
 

Region 结构是:

  type区域结构{
 ID int 
名称字符串
商店[]目的地
硕士[]硕士
 EducationCenters []目的地
  } 
   
 
 

我主要尝试这样做:

  tpl.ExecuteTemplate(resWriter,“ cities.gohtml  “,CityWithSomeData)
   
 
 

是否可以在模板内部执行类似的操作?

  {{range。}} 
 {{$ city:=。Name}} 
 {{range .Regions}} 
 {{$ region:=。 名称}} 
 {{模板“数据”。商店$ city $ region}} 
 {{end}} 
 {{end}} 
   
 
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2条回答 默认 最新

  • dongxi0523 2018-03-25 10:59
    已采纳

    Quoting from the doc of text/template, the syntax of the {{template}} action:

    {{template "name"}}
        The template with the specified name is executed with nil data.
    
    {{template "name" pipeline}}
        The template with the specified name is executed with dot set
        to the value of the pipeline.
    

    This means you may pass one optional data to the template execution, not more. If you want to pass multiple values, you have to wrap them into some single value you pass. For details, see How to pass multiple data to Go template?

    So we should wrap those data into a struct or a map. But we can't write Go code in a template. What we may do is register a function to which we pass these data, and the function may do the "packing" and return a single value which now we can pass to the {{template}} action.

    Here's an example wrapper which simply packs these into a map:

    func Wrap(shops []Destination, cityName, regionName string) map[string]interface{} {
        return map[string]interface{}{
            "Shops":      shops,
            "CityName":   cityName,
            "RegionName": regionName,
        }
    }
    

    Custom functions can be registered using the Template.Funcs() method, and don't forget you have to do this before you parse the template text.

    Here's a modified template which calls this Wrap() function to produce a single value:

    const src = `
    {{define "data"}}
        City: {{.CityName}}, Region: {{.RegionName}}, Shops: {{.Shops}}
    {{end}}
    {{- range . -}}
            {{$city:=.Name}}
            {{- range .Regions -}}
                  {{$region:=.Name}}
                  {{- template "data" (Wrap .Shops $city $region) -}}
            {{end}}
    {{- end}}`
    

    And here's a runnable example showing these in action:

    t := template.Must(template.New("cities.gohtml").Funcs(template.FuncMap{
        "Wrap": Wrap,
    }).Parse(src))
    CityWithSomeData := []City{
        {
            Name: "CityA",
            Regions: []Region{
                {Name: "CA-RA", Shops: []Destination{{"CA-RA-SA"}, {"CA-RA-SB"}}},
                {Name: "CA-RB", Shops: []Destination{{"CA-RB-SA"}, {"CA-RB-SB"}}},
            },
        },
        {
            Name: "CityB",
            Regions: []Region{
                {Name: "CB-RA", Shops: []Destination{{"CB-RA-SA"}, {"CB-RA-SB"}}},
                {Name: "CB-RB", Shops: []Destination{{"CB-RB-SA"}, {"CB-RB-SB"}}},
            },
        },
    }
    if err := t.ExecuteTemplate(os.Stdout, "cities.gohtml", CityWithSomeData); err != nil {
        panic(err)
    }
    

    Output (try it on the Go Playground):

    City: CityA, Region: CA-RA, Shops: [{CA-RA-SA} {CA-RA-SB}]
    
    City: CityA, Region: CA-RB, Shops: [{CA-RB-SA} {CA-RB-SB}]
    
    City: CityB, Region: CB-RA, Shops: [{CB-RA-SA} {CB-RA-SB}]
    
    City: CityB, Region: CB-RB, Shops: [{CB-RB-SA} {CB-RB-SB}]
    
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  • douzhangwei5265 2018-03-25 06:53

    I guess CityWithSomeData is a slice, if so have a try like that:

    type viewModel struct {
        List   []City
    }
    

    then, in your template:

    {{range .List}}
            {{$city:=.Name}}
                {{range .Regions}}
                          {{$region:=.Name}}
                          {{template "data" .Shops $city $region}}
                {{end}}
    {{end}}
    
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