英文:
Range through an arbitrary number of nested slices of structs in an HTML template in Go
问题
我正在尝试构建一个类似Reddit的网络论坛。有顶级帖子和回复，回复可以有回复，依此类推。
一个板块的结构如下：
var board map[string]*Post
以及一个Post的结构：
type Post struct {
Title string
Body string
ID string
PostNum int
Replies []*Post
}
我该如何使用模板来遍历嵌套的Replies切片（要记住每个*Post都包含一个包含*Posts的Replies切片，依此类推）？
我目前的进展：
<div id="posts">
{{ .Title }}
{{ .Body }}
<ul>
{{ range $key, $value := .Replies }}
<li class="post">
<div class="postHead">
<div class="postTitle"><b>{{ $value.ID }}</b></div>
</div>
<div class="postBody">{{ $value.PostNum }}</div>
</li>
<ul>
{{ range $key, $value := $value.Replies }}
<li class="post">
<div class="postHead">
<div class="postTitle"><b>{{ $value.ID }}</b></div>
</div>
<div class="postBody">{{ $value.PostNum }}</div>
</li>
{{ end }}
</ul>
{{ end }}
</ul>
</div>
这只允许我遍历两层回复（并且如你所见使用了重复的代码），我需要能够遍历任意层级的Replies。
英文:
I'm trying to build a web forum kind of like Reddit. There are top level posts with replies and the replies can have replies and so on.
A board looks like this:
var board map[string]*Post
and a Post:
type Post struct {
Title string
Body string
ID string
PostNum int
Replies []*Post
}
How would I use a template to range through the nested Replies slices (keeping in mind that each *Post contains a Replies slice that contains *Posts that contains Replies and so on)?
What I have so far:
<div id="posts">
{{ .Title }}
{{ .Body }}
<ul>
{{ range $key, $value := .Replies }}
<li class="post">
<div class="postHead">
<div class="postTitle"><b>{{ $value.ID }}</b></div>
</div>
<div class="postBody">{{ $value.PostNum }}</div>
</li>
<ul>
{{ range $key, $value := $value.Replies }}
<li class="post">
<div class="postHead">
<div class="postTitle"><b>{{ $value.ID }}</b></div>
</div>
<div class="postBody">{{ $value.PostNum }}</div>
</li>
{{ end }}
</ul>
{{ end }}
</ul>
</div>
This only allows me to range through two levels of replies (and as you can see uses duplicate code), I need to be able to range through an arbitrary number of levels of Replies.
答案1
得分: 7
要递归遍历一个层次结构，可以使用一个执行自身的命名模板。在下面的示例中，模板"replies"执行"replies"以显示子回复：
{{define "main"}}
<div id="post">
{{.Title}}
{{.Body}}
{{template "replies" .Replies}}
</div>
{{end}}
{{define "replies"}}
{{if .}}
<ul>
{{range . }}
<li class="post">
<div class="postHead">
<div class="postTitle"><b>{{.Title}}</b></div>
</div>
<div class="postBody">{{.Body}}</div>
{{template "replies" .Replies}}
</li>
{{end}}
</ul>
{{end}}
{{end}}
英文:
To recurse down a hierarchy, use a named template that executes itself. In the following example, the template "replies" executes "replies" to display sub-replies:
{{define "main"}}
<div id="post">
{{.Title}}
{{.Body}}
{{template "replies" .Replies}}
</div>
{{end}}
{{define "replies"}}
{{if .}}
<ul>
{{range . }}
<li class="post">
<div class="postHead">
<div class="postTitle"><b>{{.Title}}</b></div>
</div>
<div class="postBody">{{.Body}}</div>
{{template "replies" .Replies}}
</li>
{{end}}
</ul>
{{end}}
{{end}}
答案2
得分: 4
你刚刚定义了一个递归数据类型。你可以通过定义一个递归模板来渲染它：
{{define "replies"}}
<ul>
{{ range $key, $value := . }}
<li class="post">
<div class="postHead">
<div class="postTitle"><b>{{ $value.ID }}</b></div>
</div>
<div class="postBody">{{ $value.PostNum }}</div>
</li>
{{template "replies" .Replies}}
{{end}}
</ul>
{{end}}
<div id="posts">
{{ .Title }}
{{ .Body }}
{{ template "replies" .Replies }}
</div>
英文:
You just have defined a recursive data type. You can render it by defining a recursive template:
{{define "replies"}}
<ul>
{{ range $key, $value := . }}
<li class="post">
<div class="postHead">
<div class="postTitle"><b>{{ $value.ID }}</b></div>
</div>
<div class="postBody">{{ $value.PostNum }}</div>
</li>
{{template "replies" .Replies}}
{{end}}
</ul>
{{end}}
<div id="posts">
{{ .Title }}
{{ .Body }}
{{ template "replies" .Replies }}
</div>
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