Go Templates: two or more slices ranges

Question

The next code works perfect for output one slice inside the HomeTemplate.

main.go

type Item struct {
    Id          int
    Name string
    Type      string
}

var tmpl = template.Must(template.ParseGlob("tmpl/*"))

func Index(w http.ResponseWriter, r *http.Request) {

    db := database.DbConn()

    selDB, err := product.ByID()
    if err != nil {
        panic(err.Error())
    }

    i := Item{}

    resItems := []Item{}

    for selDB.Next() {

        var id int
        var product_name, product_type string

        err = selDB.Scan(&id, &product_name, &product_type)
        if err != nil {
            panic(err.Error())
        }

        i.Id = id
        i.Name = product_name
        i.Type = product_type

        resItems = append(resItems, i)

    }

    tmpl.ExecuteTemplate(w, "HomeTemplate", resItems)

    // Close database connection
    defer db.Close()
}

In the template forks fine the next code:

{{ range . }}
    {{ .Name }}<br />
{{ end }}

Why something like this does not work?

{{ range .resItems }}
    {{ .Name }}<br />
{{ end }}

What if I want output two or more slices, what I need to do or change?

Thank you

Answer 1

first question, why rang .resItems doesn't work.
In template, . means current item. like this in java. if . in some direction like range, it means the item from range operation.
if not, it means the item you passed form ExecuteTemplate() method. like in ExecuteTemplate(w, "HomeTemplate", resItems), . means resItems. so you can not use .resItems because it means resItems have a value called resItems.

second, if you have more slices to pass to template, you can add all of them to a map, like this:

t := template.New("test")
t, _ = t.Parse(`
test range 
{{range .first}} {{.}} {{end}}
{{range .second}} {{.}} {{end}}
`)
var res = make(map[string]interface{})
aa := []string{"first", "second"}
bb := []string{"123", "456"}
res["first"] = aa
res["second"] = bb
t.Execute(os.Stdout, res)

// output
test range
 first  second
 123  456

I have two array aa and bb, and add them to a map then pass it to the template. In template, . means the map, and .first got the array aa. and so as bb.

Hope this can help you...