英文:
Go Template : Use nested struct's field and {{range}} tag together
问题
我有以下嵌套结构体，我想在模板中使用{{range .Foos}}标签来迭代它们。
type Foo struct {
Field1, Field2 string
}
type NestedStruct struct {
NestedStructID string
Foos []Foo
}
我尝试使用以下html/template，但它无法访问NestedStruct中的NestedStructID。
{{range .Foos}} { source: '{{.Field1}}', target: '{{.NestedStructID}}' }{{end}}
在golang模板中有没有办法实现我想要的效果？
英文:
I have the following nested struct and I would like to iterate them in a template, in a {{range .Foos}} tag.
type Foo struct {
Field1, Field2 string
}
type NestedStruct struct {
NestedStructID string
Foos []Foo
}
I'm trying with the following html/template but it can't access the NestedStructID from NestedStruct.
{{range .Foos}} { source: '{{.Field1}}', target: '{{.NestedStructID}}' }{{end}}
Is there any way with golang templates to do what I'd like to do?
答案1
得分: 3
你不能像那样访问NestedStructID字段，因为{{range}}操作在每次迭代中将管道（点.）设置为当前元素。
你可以使用$，它被设置为传递给Template.Execute()的数据参数；所以如果你传递了一个NestedStruct的值，你可以使用$.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: '{{$.NestedStructID}}' }
{{end}}`
输出结果（在Go Playground上尝试）：
{ source: 'f1-1', target: 'nsid' }
{ source: 'f1-2', target: 'nsid' }
<nil>
这在text/template中有文档说明：
当执行开始时，$被设置为传递给Execute的数据参数，也就是dot的初始值。
英文:
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.
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 $.NestedStructID.
For example:
func main() {
t := template.Must(template.New("").Parse(x))
ns := NestedStruct{
NestedStructID: "nsid",
Foos: []Foo{
{"f1-1", "f2-1"},
{"f1-2", "f2-2"},
},
}
fmt.Println(t.Execute(os.Stdout, ns))
}
const x = `{{range .Foos}}{ source: '{{.Field1}}', target: '{{$.NestedStructID}}' }
{{end}}`
Output (try it on the Go Playground):
{ source: 'f1-1', target: 'nsid' }
{ source: 'f1-2', target: 'nsid' }
<nil>
This is documented in text/template:
> When execution begins, $ is set to the data argument passed to Execute, that is, to the starting value of dot.
通过集体智慧和协作来改善编程学习和解决问题的方式。致力于成为全球开发者共同参与的知识库，让每个人都能够通过互相帮助和分享经验来进步。
评论