去附加到一个接口键/字段是一个地图

Question

My question is about appending to a map which is a filed/key of an interface. This is required to build a JSON object. I am using map[string]interface{} to be able to append any struct types to it. I am not sure if that is a right way as I am still learning Go but I could not find a better way. Below is a link to a playground:
https://play.golang.org/p/cxpSep8OQD.

I think I need to use type accretion but I do not understand how. Any help would be useful.

Answer 1

If all you have are Group values, then declare outJson as a map of *Group:

outJson := make(map[string]*Group, len(groups))

Playground Example

If the map can contain different value types, then use a type assertion to access the group:

    g, ok := outJson["a"].(*Group)
    if !ok {
        panic("handle error a better way")
    }
    g.Hosts = append(g.Hosts, "hostname")

Playground Example