golang, type int does not support indexing

I have a trouble in a part of code. I'm writing on revel framework(to be clear). This is a Worker go routine, and I want it to do several things:

1. switch the struct type of the stat variable, according to the
   source, that would come. I made a switch, but before the all other
   code would be correct, I don't really know if switch is written
   properly.

2. I get cache for the date, and put it in new Work item.

3. I send Work to channel

here is what I got by now:

func worker(in <-chan Task, out chan <- Work, wg *sync.WaitGroup) {

	for t := range in {
		for sourceName, charts := range t.Request.Charts {

			var stat interface{}

			switch sourceName {
			case "noagg":
				 stat = stat.([]NoaggModel)
			case "oracle":
				stat = stat.([]OracleModel)
			default:
				panic("Invalid type for Work model!")
			}

			w := Work{Name:"", Data:""}

			err := cache.Get(string(sourceName)+"_"+string(t.Date), &stat);

			for chart := range charts{
				w.Name = chart["name"]

				if err == nil{
					w.Data = countDataByName( stat, t.Request.Filters, string(chart["name"]))
				}
				out <- w
			}
		}
	}
	wg.Done() // this worker is now done; let the WaitGroup know.
}

But now I got error that invalid operation: chart["name"] (type int does not support indexing)

But I have structs :

type Chart struct {
	Name string           `json:"name"`
	Type string           `json:"type"`
}

type Filter struct {
	DayStart string `json:"dayStart"`
	DayEnd string `json:"dayEnd"`
	TimePeriods interface{} `json:"timePeriods"`
	Lines []string `json:"lines"`
}

type Task struct {
	Date string
	Request ChartOptins
}

type Work struct {
	Name string
	Data interface{}
}

How should I write in a better way the correct switch, if the type of struct for cache can be different, and why is my name adding is bad and call error?

The for in the slice is missing a variable

for chart := range charts{

when iterating on a slice the first variable is the key and the second is the real value you want. In this case you can omit the key (an int) so the proper instruction should be

for _, chart := range charts{