interface{} to []string - go

Question

I'm trying to parse some YAML file into go struct, but the file itself can not be treated as ordinary go structure: some of values may be either string or map[string][]string.
What I have tried is to do custom unmarshal func:
func (domain *Domain) UnmarshalYAML(unmarshal func(interface{}) error) error {
fmt.Println("Parsing domain")
var hostUrl interface{}
unmarshal(&hostUrl)
fmt.Println(reflect.TypeOf(hostUrl))
switch hostUrl.(type) {
case string:
domain.Host = hostUrl.(string)
case map[interface {}]interface {}:
fmt.Println("got map")
v := reflect.ValueOf(hostUrl)
fmt.Println(v.MapKeys()[0])
for _, host := range v.MapKeys() {
domain.Host = host.Interface().(string)
fmt.Println(v.MapIndex(host))
//HERE I NEED TO DO SMTH LIKE THIS:
//domain.Urls = v.MapIndex(host).([]string)
}
default:
return errors.New("invalid config file, cant parse domains")
}
return nil
}
My domain structure looks like this:
type Domain struct {
Host string
Urls []string
}
But this code causes an error:
invalid type assertion: v.MapIndex(host).([]string) (non-interface type reflect.Value on left)
So my question may sound like "how to convert {}interface to []string?" or it may become more complex: "How to parse YAML file into go struct if some key can be either simple string or map[string][]string?"
UPDATE:
Responding to #mkopriva:
fmt.Println(v.MapIndex(host))
for url := range v.MapIndex(host).Interface().([] interface{}) {
fmt.Println(url)
}
Didnt help me, as now it just prints some integers (0), but there should be a string. Converting it to an array of strings throws another error:
panic: interface conversion: interface {} is []interface {}, not []string

Answer 1

Thanks to #mkopriva and the snippet from the sandbox. The reason of integer appearing during iterating over v.MapIndex(host).Interface().([] interface{}) is that range returns two values: index and corresponding to that index value. I was only catching the first one. It is why I wasn't able to cast it to string.
Working loop:
for _, url := range v.MapIndex(host).Interface().([] interface{}) {
fmt.Println(url.(string))
domain.Urls = append(domain.Urls,url.(string) )
}