Question

我试图编写一个通用函数来获取地图的键，如下所示：

func MapKeys(theMap map[interface{}]interface{}) ([]interface{},error) {

    if theMap == nil {
        return nil,errors.New("MapKeys arg is nil")
    }

    var keys = make([]interface{}, len(theMap), len(theMap))

    i := 0
    for idx,_ := range theMap {
        keys[i] = idx
        i++
    }

    return keys, nil
}

A）有更好的方法吗？和B）调用此函数时，如何将原始地图类型转换为map [interface {}] interface {}？

Answer 1

您无法将现有地图投射到map[interface{}]interface{}。你必须使用反射：

func MapKeys(theMap interface{}) ([]interface{}, error) {
    if theMap == nil {
        return nil,errors.New("MapKeys arg is nil")
    }

    v := reflect.ValueOf(theMap) // v is now a reflect.Value type
    if v.Kind() != reflect.Map {
        return nil, errors.New("Argument is not a map")
    }
    var keys = make([]interface{}, v.Len(), v.Len())

    for i, key := range v.MapKeys() {
        keys[i] = key.Interface() // key is also a reflect.Value, key.Interface()
                                  // converts it back into an interface
    }
    return keys, nil
}

工作示例：https://play.golang.org/p/h9ZfnLHXgX

投射地图类型

1 个答案: