在golang html模板中访问{{range。}}范围之外的struct变量

<!DOCTYPE html>
<html>
<head>
    <title> Test </title>
</head>
<body>
    <div>
        <h2>Reply</h2>
        <form action="/post/{{$threadID}}" method="POST">
        <input type="text" name="subject" />
        <input type="text" name="name" value="Anonymous" />
        <input type="text" name="message" />
        <input type="submit" value="submit" />
        </form>
    </div>
    <div>
        {{range .}}
        {{$threadID := .ThreadID}}
        <h3>{{.Subject}}</h3>
        <h3>{{.Name}}</h3>
        <div>{{.DatePosted}}</div>
        <div><p>{{.Text}}</p></div>
        <br /><br />
        {{end}}
    </div>
</body>

I have this template, there is a form at the top of the page that requires the threadID from ANY one of the Posts sent (they're all the same, a slice of all posts with a certain threadID), this obviously doesn't work, my only other idea was something along the lines of

{{range .}}
    {{if $threadID == nil}}
        $threadID := .ThreadID
        //build the form same as above
    {{end}}
    <h3>{{.Subject}}</h3>
    <h3>{{.Name}}</h3>
    <div>{{.DatePosted}}</div>
    <div><p>{{.Text}}</p></div>
    <br /><br />
{{end}}

Here is the Post structure and methods if any of the above is unclear.

type Post struct {
threadID int
subject string
name string
text string
date_posted string
}

func (p *Post) ThreadID()   int    { return p.threadID    }
func (p *Post) Subject()    string { return p.subject     }
func (p *Post) Name()       string { return p.name        }
func (p *Post) Text()       string { return p.text        }
func (p *Post) DatePosted() string { return p.date_posted }

And the origin of the slice of posts sent to the template

threadID := r.URL.Path[len("/reply/"):]
replies, err := i.db.Query("SELECT * FROM latest_threads where thread_id="+threadID);