为何在 html/template 中未显示传递的变量？

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我不明白为什么传递的变量没有用 html/template 渲染

这是在浏览器中呈现的内容：

这是所有传递的变量：[0xc0000a8ec0 0xc0000a8f80 0xc0000a9040 0xc0000a9100]

城市人口州国家首都

这是日志：

$ go 运行 main.go

2019/11/27 11:00:39 **** => &city has &main.city{name:"washington d.c.", state:"", country:"usa", capital:false, population:680000} before appending to cities ****
2019/11/27 11:00:39 **** => &city has &main.city{name:"los angeles", state:"ca", country:"usa", capital:false, population:3900000} before appending to cities ****
2019/11/27 11:00:39 **** => &city has &main.city{name:"san francisco", state:"ca", country:"usa", capital:false, population:860000} before appending to cities ****
2019/11/27 11:00:39 **** => &city has &main.city{name:"tokyo", state:"", country:"japan", capital:true, population:9000000} before appending to cities ****
**** => cities outside {} has 4

这是处理函数：

func indexhandler(w http.responsewriter, r *http.request) {
    projectid := "xxxxxxxxxxxxxx"
    ctx := context.background()

    client, _ := firestore.newclient(ctx, projectid)

    query := client.collection("cities").documents(ctx)
    defer query.stop()
    cities := make([]*city, 0)
    for {
        doc, err := query.next()
        if err == iterator.done {
            break
        }
        c := doc.data()

        // is there an easier way to populate the city struct
        city := city{
            name:       c["name"].(string),
            country:    c["country"].(string),
            population: c["population"].(int64),
        }
        // this is my ugly solution to dealing with nil value from firestore
        _, ok := c["capital"]
        if ok {
            city.capital = c["capital"].(bool)
        }
        state, ok := c["state"].(string)
        if ok {
            city.state = state
        }
        log.printf("**** => &city has %#v before appending to cities ****", &city)
        cities = append(cities, &city)

    }

    fmt.printf("**** => cities outside {} has %d", len(cities))
    indextemplate.execute(w, cities)    
}

这是index.html模板：

{% autoescape true %}







        
This is all the passed variables: {{ . }}
    

    {{ range .cities }}
    
    {{ end }}



        
  
City
 
Population
 
 State
Country
 
Capital
 
  
testing
 
testing
 
testing
testing
 
testing
 
    
  
{{.Name}}
 
{{ .Population}}
 
{{ .State}}
{{.Country}}
 
{{.Capital}}
 
{{ $cities := . }}



{% endautoescape %}

解决方案

永远不要遗漏错误，检查 indextemplate.execute(w, cars) 返回的内容。它可能揭示了原因：

您将 cities 作为数据传递，它是一个切片。没有 cities 字段或方法。传递的数据成为点，因此您必须在点上进行范围。

而不是：

{{ range .cities }}

用途：

{{ range . }}

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