How to dynamically get a property by name from a C# ExpandoObject?

Question

I have an ExpandoObject and want to make a getter for it that will return a property by name at runtime, where the name is specified in a string instead of hardcoded.

For example, I CAN do this:

account.features.isEmailEnabled;

and that will return true. account is a ExpandoObject, and features is also an ExpandoObject. So I have an ExpandoObject that contains other ExpandoObjects.

So what I want to be able to do is this:

account.features.GetProperty("isEmailEnabled");

and have that return true.

The reason is that I have many features, and I want to be able to write one generic getter method where I can pass in the name of the feature I want, and the method will pass me back the value for account.features.whatever (where "whatever" is specified by passing in a string to the generic getter method). Otherwise I am going to have to write 30-some getters one for each feature.

I did a lot of research and tried doing something like:

var prop = account.features.GetType();  
// this returns System.Dyanmic.ExpandoObject

followed by

var value = prop.GetProperty(featureNameAsString);

but value always comes back as null. I don't understand why. In the watch window I can do account.features.isEmailEnabled and it shows true and says its a boolean. But if I try to get at this value using the approach above and pass in isEmailEnabled as the featureNameAsString I just get null.

Can someone please tell me what I may be doing wrong and what's a good approach, without it being too complex?

I am working with ASP.NET under the 4.5.1 framework.

Marc Gravell · Accepted Answer · 2013-10-02 14:31:14Z

116

ExpandoObject provides access both via dynamic and via IDictionary<string,object> - so you could just use the dictionary API:

var byName = (IDictionary<string,object>)account.features;
bool val = (bool)byName["isEmailEnabled"];

Or if the name is fixed, just:

bool val = ((dynamic)account).features.isEmailEnabled;

answered Oct 2, 2013 at 14:31

Marc Gravell

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Maxter · Accepted Answer · 2024-02-20 20:37:46Z

3

You can use an extension method to do what you need:

public static T Get<T>(this ExpandoObject expO, string prop)
{
    return (T)((IDictionary<string, object>)expO)[prop];
}

Example usage:

account.features.Get<bool>("isEmailEnabled");

answered Feb 20, 2024 at 20:37

Maxter

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