Question

我正在尝试访问存储在String，UnknownClass类型的字典中的对象。我有密钥，并且知道值是几个容器类之一。由于值传递给接受对象的方法，因此我不需要知道存储为值的类的类型。我还需要调用ContainsKey来确认密钥是否存在。

我尝试了以下方法但没有成功：

Dictionary<String, object> list = (Dictionary<String, object>)source.GetType().GetProperty(dictionaryName).GetValue(source, null);
nextSource = list[key];

这给了我一个投射错误，并且：

nextSource = source.GetType().GetMethod("get_Item").Invoke(source, new object[] { key });

这给了我一个空的引用异常。

这里有一些代码，虽然我不太确定它会有多大帮助。

private void SetValue(object source, String path, String value)
{
    if (path.Contains('.'))
    {
        //  If this is not the ending Property, continue recursing
        int index = path.IndexOf('.');
        String property = path.Substring(0, index);

        object nextSource;
        if(property.Contains("*"))
        {
            path = path.Substring(index + 1);
            index = path.IndexOf('.');
            String dictionaryName = path.Substring(0, index);

            Dictionary<String, object> list = (Dictionary<String, object>)source.GetType().GetProperty(dictionaryName).GetValue(source, null);
            nextSource = list[property.Substring(1)];
            //property = property.Substring(1);
            //nextSource = source.GetType().GetMethod("Item").Invoke(source, new[] { property });
        } ...

正在访问的字典在PersonObject类中定义如下：

public class PersonObject
{
    public String Name { get; set; }
    public AddressObject Address { get; set; }
    public Dictionary<String, HobbyObject> Hobbies { get; set; }

在此阶段，Path的值设置为"*Hiking.Hobbies.Hobby"。基本上，路径字符串允许我导航到子类中的Property，我需要Dictionary来访问同一类列表的属性。

Answer 1

Dictionary<TKey, TValue> Class实现了非通用IDictionary Interface。因此，如果您有一个包含对object实例的引用的tye Dictionary<String, HobbyObject>变量，您可以按如下方式检索字典中的值：

object obj = new Dictionary<String, HobbyObject>
{
    { "Hobby", new HobbyObject() }
};

IDictionary dict = obj as IDictionary;
if (dict != null)
{
    object value = dict["Hobby"];
    // value is a HobbyObject
}

Answer 2

听起来你正试图这样做：

var source = new Dictionary<string, object>();
var key = "some key";
source.Add(key, "some value");

var property = source.GetType().GetProperty("Item");
var value = property.GetValue(source, new[] { key });

Console.WriteLine(value.ToString()); // some value

更新：问题是Dictionary<string, HobbyObject>无法投放到Dictionary<string, object>。我想你必须这样做：

private void SetValue(object source, String path, String value)
{
    if (path.Contains('.'))
    {
        //  If this is not the ending Property, continue recursing
        int index = path.IndexOf('.');
        String property = path.Substring(0, index);

        object nextSource;
        if(property[0] = '*')
        {
            path = path.Substring(index + 1);
            index = path.IndexOf('.');
            String dictionaryName = path.Substring(0, index);

            property = property.Substring(1);

            Object list = source.GetType().GetProperty(dictionaryName)
                                .GetValue(source, null);
            nextSource = list.GetType().GetProperty("Item")
                             .GetValue(list, new[] { property });
        }

使用反射获取字典值

2 个答案: