Home » c# » How do I check if a property exists on a dynamic anonymous type in c#?

How do I check if a property exists on a dynamic anonymous type in c#?

Posted by: admin November 29, 2017 Leave a comment

Questions:

I have an anonymous type object that I receive as a dynamic from a method
I would like to check in a property exists on that object.

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

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

How would I implement IsSettingExist ?

Answers:
  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"));

Output:

 True
 False

Questions:
Answers:
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;
}

Questions:
Answers:

if you can control creating/passing the settings object, i’d recommend using an ExpandoObject instead.

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 ....
}

Questions:
Answers:

This is working for me-:

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

               return false;
           }

       }

Questions:
Answers:

Merging and fixing answers from Serj-TM and user3359453 so that it works with both ExpandoObject and DynamicJsonObject. This works for me.

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;
}

Questions:
Answers:

Using reflection, this is the function i use :

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

then..

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

Questions:
Answers:

None of the solutions above worked for dynamic that comes from Json, I however managed to transform one with Try catch (by @user3359453) by changing exception type thrown (KeyNotFoundException instead of RuntimeBinderException) into something that actually works…

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

enter image description here

Hope this saves you some time.