c# - 如何检查属性是否存在于c#中的动态匿名类型？

Question

我有一个匿名类型对象，我从我想检查该对象上存在的属性的方法中作为动态接收。

....
var settings = new {
                   Filename="temp.txt",
                   Size=10
}
...

function void Settings(dynamic settings) {
var exists = IsSettingExist(settings,"Filename")
}

我将如何实现 IsSettingExist ？

Answer 1

  public static bool IsPropertyExist(dynamic settings, string name)
  {
    if (settings is ExpandoObject)
      return ((IDictionary<string, object>)settings).ContainsKey(name);

    return settings.GetType().GetProperty(name) != null;
  }

  var settings = new {Filename = @"c:\temp\q.txt"};
  Console.WriteLine(IsPropertyExist(settings, "Filename"));
  Console.WriteLine(IsPropertyExist(settings, "Size"));

输出：

 True
 False

Answer 2

public static bool HasProperty(dynamic obj, string name)
{
    Type objType = obj.GetType();

    if (objType == typeof(ExpandoObject))
    {
        return ((IDictionary<string, object>)obj).ContainsKey(name);
    }

    return objType.GetProperty(name) != null;
}

Answer 3

如果您可以控制创建/传递设置对象，我建议您改用 ExpandoObject。

dynamic settings = new ExpandoObject();
settings.Filename = "asdf.txt";
settings.Size = 10;
...

function void Settings(dynamic settings)
{
    if ( ((IDictionary<string, object>)settings).ContainsKey("Filename") )
        .... do something ....
}

Answer 4

这适用于匿名类型、 ExpandoObject 、 Nancy.DynamicDictionary或任何其他可以转换为IDictionary<string, object> 。

    public static bool PropertyExists(dynamic obj, string name) {
        if (obj == null) return false;
        if (obj is IDictionary<string, object> dict) {
            return dict.ContainsKey(name);
        }
        return obj.GetType().GetProperty(name) != null;
    }

Answer 5

合并和修复来自 Serj-TM 和 user3359453 的答案，以便它同时适用于 ExpandoObject 和 DynamicJsonObject。 这对我有用。

public static bool HasPropertyExist(dynamic settings, string name)
{
    if (settings is System.Dynamic.ExpandoObject)
        return ((IDictionary<string, object>)settings).ContainsKey(name);

    if (settings is System.Web.Helpers.DynamicJsonObject)
    try
    {
        return settings[name] != null;
    }
    catch (KeyNotFoundException)
    {
        return false;
    }


    return settings.GetType().GetProperty(name) != null;
}

Answer 6

这对我有用-：

  public static bool IsPropertyExist(dynamic dynamicObj, string property)
       {
           try
           {
               var value=dynamicObj[property].Value;
               return true;
           }
           catch (RuntimeBinderException)
           {

               return false;
           }

       }

Answer 7

使用反射，这是我使用的功能：

public static bool doesPropertyExist(dynamic obj, string property)
{
    return ((Type)obj.GetType()).GetProperties().Where(p => p.Name.Equals(property)).Any();
}

然后..

if (doesPropertyExist(myDynamicObject, "myProperty")){
    // ...
}

Answer 8

上面的解决方案都不适用于来自Json dynamic ，但是我设法通过将抛出的异常类型（ KeyNotFoundException而不是RuntimeBinderException ）更改为实际工作的东西来使用Try catch （由@user3359453 提供）转换一个...

public static bool HasProperty(dynamic obj, string name)
    {
        try
        {
            var value = obj[name];
            return true;
        }
        catch (KeyNotFoundException)
        {
            return false;
        }
    }

希望这可以为您节省一些时间。

Answer 9

如果有人需要处理来自 Json 的动态对象，我已修改 Seth Reno 答案以处理从 NewtonSoft.Json.JObjcet 反序列化的动态对象。

public static bool PropertyExists(dynamic obj, string name)
    {
        if (obj == null) return false;
        if (obj is ExpandoObject)
            return ((IDictionary<string, object>)obj).ContainsKey(name);
        if (obj is IDictionary<string, object> dict1)
            return dict1.ContainsKey(name);
        if (obj is IDictionary<string, JToken> dict2)
            return dict2.ContainsKey(name);
        return obj.GetType().GetProperty(name) != null;
    }

Answer 10

我遇到的动态是Newtonsoft.Json.Linq.JObject而不是IDictionary

我添加了额外的如果它有效。

public static bool PropertyExists(dynamic obj, string name)
{
    if (obj == null) return false;

    else if (obj is IDictionary<string, object> dict)
    {
        return dict.ContainsKey(name);
    }

    else if (obj is Newtonsoft.Json.Linq.JObject jObject)
    {
        return jObject.ContainsKey(name);
    }

    else
    {
        return obj.GetType().GetProperty(name) != null;
    }
}

Answer 11

为了扩展@Kuroro 的答案，如果您需要测试该属性是否为空，下面应该可以工作。

public static bool PropertyExistsAndIsNotNull(dynamic obj, string name)
{
    if (obj == null) return false;
    if (obj is ExpandoObject)
    {
        if (((IDictionary<string, object>)obj).ContainsKey(name))
            return ((IDictionary<string, object>)obj)[name] != null;
        return false;
    }
    if (obj is IDictionary<string, object> dict1)
    {
        if (dict1.ContainsKey(name))
            return dict1[name] != null;
        return false;
    }
    if (obj is IDictionary<string, JToken> dict2)
    {
        if (dict2.ContainsKey(name))
            return (dict2[name].Type != JTokenType.Null && dict2[name].Type != JTokenType.Undefined);
        return false;
    }
    if (obj.GetType().GetProperty(name) != null)
        return obj.GetType().GetProperty(name).GetValue(obj) != null;
    return false;
}

Answer 12

我有一个匿名类型对象，该对象是我想检查的对象中存在的属性作为动态方法接收的。

....
var settings = new {
                   Filename="temp.txt",
                   Size=10
}
...

function void Settings(dynamic settings) {
var exists = IsSettingExist(settings,"Filename")
}

我将如何实现IsSettingExist？

Answer 13

这也适用于 DynamicJsonObject：

  public static bool PropertyExists(dynamic settings, string name)
  {
    if (settings is ExpandoObject)
      return ((IDictionary<string, object>)settings).ContainsKey(name);
    else if (settings is DynamicJsonObject)
      return ((DynamicJsonObject)settings).GetDynamicMemberNames().Contains(name);

    return settings.GetType().GetProperty(name) != null;
  }

Answer 14

    public static void Test()
    {
        int LOOP_LENGTH = 100000000;
        {
            long first_memory = GC.GetTotalMemory(true);
            var stopWatch = Stopwatch.StartNew();

            Console.WriteLine("doesPropertyExist");

            dynamic testdo = new { A = 1, B = (string)null, C = "A" };
            for (int i = 0; i < LOOP_LENGTH; i++)
            {
                if (!TestDynamic.doesPropertyExist(testdo, "A"))
                {
                    Console.WriteLine("throw find");
                    break;
                }

                if (TestDynamic.doesPropertyExist(testdo, "ABC"))
                {
                    Console.WriteLine("throw not find");
                    break;
                }
            }
            stopWatch.Stop();
            var last_memory = GC.GetTotalMemory(true);
            Console.WriteLine($" Time:{stopWatch.Elapsed.TotalSeconds}s\t Memory:{last_memory - first_memory}");
        }

        {
            long first_memory = GC.GetTotalMemory(true);
            var stopWatch = Stopwatch.StartNew();

            Console.WriteLine("HasProperty");

            dynamic testdo = new { A = 1, B = (string)null, C = "A" };
            for (int i = 0; i < LOOP_LENGTH; i++)
            {
                if (!TestDynamic.HasProperty(testdo, "A"))
                {
                    Console.WriteLine("throw find");
                    break;
                }

                if (TestDynamic.HasProperty(testdo, "ABC"))
                {
                    Console.WriteLine("throw not find");
                    break;
                }
            }
            stopWatch.Stop();
            var last_memory = GC.GetTotalMemory(true);
            Console.WriteLine($" Time:{stopWatch.Elapsed.TotalSeconds}s\t Memory:{last_memory - first_memory}");
        }


        {
            long first_memory = GC.GetTotalMemory(true);
            var stopWatch = Stopwatch.StartNew();

            Console.WriteLine("IsPropertyExist");

            dynamic testdo = new { A = 1, B = (string)null, C = "A" };
            for (int i = 0; i < LOOP_LENGTH; i++)
            {
                if (!TestDynamic.IsPropertyExist(testdo, "A"))
                {
                    Console.WriteLine("throw find");
                    break;
                }

                if (TestDynamic.IsPropertyExist(testdo, "ABC"))
                {
                    Console.WriteLine("throw not find");
                    break;
                }
            }
            stopWatch.Stop();
            var last_memory = GC.GetTotalMemory(true);
            Console.WriteLine($" Time:{stopWatch.Elapsed.TotalSeconds}s\t Memory:{last_memory - first_memory}");
        }

        {
            long first_memory = GC.GetTotalMemory(true);
            var stopWatch = Stopwatch.StartNew();

            Console.WriteLine("IsPropertyExistBinderException");

            dynamic testdo = new { A = 1, B = (string)null, C = "A" };
            for (int i = 0; i < LOOP_LENGTH; i++)
            {
                if (!TestDynamic.IsPropertyExistBinderException(testdo, "A"))
                {
                    Console.WriteLine("throw find");
                    break;
                }

                if (TestDynamic.IsPropertyExistBinderException(testdo, "ABC"))
                {
                    Console.WriteLine("throw not find");
                    break;
                }
            }
            stopWatch.Stop();
            var last_memory = GC.GetTotalMemory(true);
            Console.WriteLine($" Time:{stopWatch.Elapsed.TotalSeconds}s\t Memory:{last_memory - first_memory}");
        }


        {
            long first_memory = GC.GetTotalMemory(true);
            var stopWatch = Stopwatch.StartNew();

            Console.WriteLine("PropertyExists");

            dynamic testdo = new { A = 1, B = (string)null, C = "A" };
            for (int i = 0; i < LOOP_LENGTH; i++)
            {
                if (!TestDynamic.PropertyExists(testdo, "A"))
                {
                    Console.WriteLine("throw find");
                    break;
                }

                if (TestDynamic.PropertyExists(testdo, "ABC"))
                {
                    Console.WriteLine("throw not find");
                    break;
                }
            }
            stopWatch.Stop();
            var last_memory = GC.GetTotalMemory(true);
            Console.WriteLine($" Time:{stopWatch.Elapsed.TotalSeconds}s\t Memory:{last_memory - first_memory}");
        }


        {
            long first_memory = GC.GetTotalMemory(true);
            var stopWatch = Stopwatch.StartNew();

            Console.WriteLine("PropertyExistsJToken");

            dynamic testdo = new { A = 1, B = (string)null, C = "A" };
            for (int i = 0; i < LOOP_LENGTH; i++)
            {
                if (!TestDynamic.PropertyExistsJToken(testdo, "A"))
                {
                    Console.WriteLine("throw find");
                    break;
                }

                if (TestDynamic.PropertyExistsJToken(testdo, "ABC"))
                {
                    Console.WriteLine("throw not find");
                    break;
                }
            }
            stopWatch.Stop();
            var last_memory = GC.GetTotalMemory(true);
            Console.WriteLine($" Time:{stopWatch.Elapsed.TotalSeconds}s\t Memory:{last_memory - first_memory}");
        }




    }

    public static bool IsPropertyExist(dynamic settings, string name)
    {
        if (settings is ExpandoObject)
            return ((IDictionary<string, object>)settings).ContainsKey(name);

        return settings.GetType().GetProperty(name) != null;
    }

    public static bool HasProperty(dynamic obj, string name)
    {
        Type objType = obj.GetType();

        if (objType == typeof(ExpandoObject))
        {
            return ((IDictionary<string, object>)obj).ContainsKey(name);
        }

        return objType.GetProperty(name) != null;
    }


    public static bool PropertyExists(dynamic obj, string name)
    {
        if (obj == null) return false;
        if (obj is IDictionary<string, object> dict)
        {
            return dict.ContainsKey(name);
        }
        return obj.GetType().GetProperty(name) != null;
    }

    // public static bool HasPropertyExist(dynamic settings, string name)
    // {
    //     if (settings is System.Dynamic.ExpandoObject)
    //         return ((IDictionary<string, object>)settings).ContainsKey(name);
    //     if (settings is DynamicJsonObject)
    //         try
    //         {
    //             return settings[name] != null;
    //         }
    //         catch (KeyNotFoundException)
    //         {
    //             return false;
    //         }
    //     return settings.GetType().GetProperty(name) != null;
    // }

    public static bool IsPropertyExistBinderException(dynamic dynamicObj, string property)
    {
        try
        {
            var value = dynamicObj[property].Value;
            return true;
        }
        catch (RuntimeBinderException)
        {

            return false;
        }

    }

    public static bool HasPropertyFoundException(dynamic obj, string name)
    {
        try
        {
            var value = obj[name];
            return true;
        }
        catch (KeyNotFoundException)
        {
            return false;
        }
    }


    public static bool doesPropertyExist(dynamic obj, string property)
    {
        return ((Type)obj.GetType()).GetProperties().Where(p => p.Name.Equals(property)).Any();
    }

    public static bool PropertyExistsJToken(dynamic obj, string name)
    {
        if (obj == null) return false;
        if (obj is ExpandoObject)
            return ((IDictionary<string, object>)obj).ContainsKey(name);
        if (obj is IDictionary<string, object> dict1)
            return dict1.ContainsKey(name);
        if (obj is IDictionary<string, JToken> dict2)
            return dict2.ContainsKey(name);
        return obj.GetType().GetProperty(name) != null;
    }

    // public static bool PropertyExistsJsonObject(dynamic settings, string name)
    // {
    //     if (settings is ExpandoObject)
    //         return ((IDictionary<string, object>)settings).ContainsKey(name);
    //     else if (settings is DynamicJsonObject)
    //         return ((DynamicJsonObject)settings).GetDynamicMemberNames().Contains(name);

    //     return settings.GetType().GetProperty(name) != null;
    // }
}

是否存在属性

时间：59.5907507s 内存：403680

有属性

时间：30.8231781s 内存：14968

是否存在属性

时间：39.6179575s 内存：97000

IsPropertyExistBinderException 抛出 find

属性存在

时间：56.009761s 内存：13464

PropertyExistsJToken

时间：61.6146953s 内存：15952

Answer 15

为了节省其他人的时间，这个答案涵盖了很多使用 Newtonstoft Json 反序列化动态搜索这个问题的人：

dynamic dynamicObject = JsonConvert.DeserializeObject<dynamic>(json);
if (IsContainsKey(dynamicObject, "searchText"))
    searchText = dynamicObject.searchText;

bool IsContainsKey(dynamic newtonsoftDynamic, string propertyName) {
    return (newtonsoftDynamic as JObject).ContainsKey(propertyName);
}

或者只是在代码中：

JObject obj = dynamicObject as JObject;
string searchText = string.Empty;
if (obj.ContainsKey("searchText"))
    searchText = obj.Value<string>("searchText");

没有例外，通过 Newtonsoft 进行正确处理，但您仍然可以将 dynamicObject.xxx 用于您知道将始终存在的属性。