Remove null values from JSON with Golang - https://www.ribice.ba/golang-null-values/

trim-nulls.go

func removeNulls(m map[string]interface{}) {
	val := reflect.ValueOf(m)
	for _, e := range val.MapKeys() {
		v := val.MapIndex(e)
		if v.IsNil() {
			delete(m, e.String())
			continue
		}
		switch t := v.Interface().(type) {
		// If key is a JSON object (Go Map), use recursion to go deeper
		case map[string]interface{}:
			removeNulls(t)
		}
	}
}

This does not take into account that a key might be empty and leaves behind empty keys (e.g. {"foo":{}}).