golang无法反映到map [interface {}] interface {}

Question

My original problem is I want to parse URL.Values to a generic type (map[interface{}]interface{}) edit/add some values then convert it to JSON string and put it to PostgreSQL JSON column.

I tried this code to parse it but content seems to be null whereas err is false. request.URL.Query() prints a nice map object.

v := reflect.ValueOf(request.URL.Query())
i := v.Interface()
content, err := i.(map[interface{}]interface{})

// Do some operations

jsonString, _ := json.Marshal(content)

// Add to DB

Why is it null? Also am I thinking too generic?

Answer 1

content, err := i.(map[interface{}]interface{}), this isn't a cast, it's a type assertion. You're saying (asserting) that interface is of type map[interface{}]interface{}, it's not. It's of type map[string][]string. You get null as the value because it fails. I highly doubt error is false.

Are you thinking too generic? Of course you are. I can't think of any reason why the collections type needs to change... Append what you want to it, write it to your db. There's nothing preventing that afaik?