patterngoCritical

Iterating through map in template

Submitted by: @import:stackoverflow-api·Mar 10, 2026·

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iteratingthroughtemplatemap

Problem

I am trying to display a list gym classes (Yoga, Pilates etc). For each class type there are several classes, so I want to group all the Yoga classes, and all the Pilates classes and so on.

I made this function to take a slice and make a map of it

func groupClasses(classes []entities.Class) map[string][]entities.Class {
    classMap := make(map[string][]entities.Class)
    for _, class := range classes {
        classMap[class.ClassType.Name] = append(classMap[class.ClassType.Name], class)
    }
    return classMap
}

The problem is now how can I iterate through it, according to http://golang.org/pkg/text/template/, you need to access it in .Key format, I don't know the keys (unless I also passed a slice of keys into the template). How do I unpack this map in my view.

All I have currently is

{{ . }}

which displays something like:

map[Pilates:[{102 PILATES ~/mobifit/video/ocen.mpg 169 40 2014-05-03 23:12:12 +0000 UTC 2014-05-03 23:12:12 +0000 UTC 1899-12-30 00:00:00 +0000 UTC {PILATES Pilates 1 2014-01-22 21:46:16 +0000 UTC} {1 leebrooks0@gmail.com password SUPERADMIN Lee Brooks {Male true} {1990-07-11 00:00:00 +0000 UTC true} {1.85 true} {88 true} 2014-01-22 21:46:16 +0000 UTC {0001-01-01 00:00:00 +0000 UTC false} {0001-01-01 00:00:00 +0000 UTC false} {0001-01-01 00:00:00 +0000 UTC false}} [{1 Mat 2014-01-22 21:46:16 +0000 UTC}]} {70 PILATES ~/mobifit/video/ocen.mpg 119 66 2014-03-31 15:12:12 +0000 UTC 2014-03-31 15:12:12 +0000 UTC 1899-12-30 00:00:00 +0000 UTC

Solution

Check the Variables section in the Go template docs. A range may declare two variables, separated by a comma. The following should work:

{{ range $key, $value := . }}
   {{ $key }}: {{ $value }}
{{ end }}

Code Snippets

{{ range $key, $value := . }}
   <li><strong>{{ $key }}</strong>: {{ $value }}</li>
{{ end }}

Context

Stack Overflow Q#21302520, score: 244

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