How to detect if a property exists on an ExpandoObject?

c# dynamic expandoobject
Softlion picture Softlion · May 15, 2010 · Viewed 92.6k times · Source

In javascript you can detect if a property is defined by using the undefined keyword: 

if( typeof data.myProperty == "undefined" ) ...

How would you do this in C# using the dynamic keyword with an ExpandoObject and without throwing an exception?

Answer

Dykam picture Dykam · May 15, 2010

According to MSDN the declaration shows it is implementing IDictionary:

public sealed class ExpandoObject : IDynamicMetaObjectProvider, 
    IDictionary<string, Object>, ICollection<KeyValuePair<string, Object>>, 
    IEnumerable<KeyValuePair<string, Object>>, IEnumerable, INotifyPropertyChanged

You can use this to see if a member is defined:

var expandoObject = ...;
if(((IDictionary<String, object>)expandoObject).ContainsKey("SomeMember")) {
    // expandoObject.SomeMember exists.
}

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