Add property to ExpandoObject with the same name as a string

Question

Is there a way to add a property to an ExpandoObject with the same name as a string value?

For example, if I have:

string propName = "ProductNumber";
dynamic obj = new System.Dynamic.ExpandoObject();

I can create the property ProductNumber like:

obj.ProductNumber = 123;

But, can I create the property obj.ProductNumber based on the string propName? So, if I don't know what the name of the property will be in advanced, I can create it based on this input. If this is not possible with ExpandoObject, any other areas of C# I should look into?

Overcash

possible duplicate of Adding unknown (at design time) properties to an ExpandoObject – Schizomycete

Practical use of the above found here: #2974508 – Reaves

Answer 1

ExpandoObject implements IDictionary<string, object>:

((IDictionary<string, object>)obj)[propName] = propValue

I don't know off the top of my head whether you can use the indexer syntax with a dynamic reference (i.e., without the cast), but you can certainly try it and find out.

Qualls

you can't index an ExpandoObject as you've done in your first example – Foggy

Second example is good. First example gives Cannot apply indexing with [] to an expression of type 'System.Dynamic.ExpandoObject' – Overcash

@Overcash thanks -- I had forgotten that the indexer is an explicit interface implementation. Answer edited. – Qualls

@VBRonPaulFan yes, I had forgotten that the interface implementation is explicit. I've edited the answer. – Qualls

man, i am so glad i found this post. i was about to implement some object off of DynamicObject from some other tutorials just to get this ability. life and time saver thanks!! :D – Gaberdine

Answer 2

Cast the ExpandoObject to an IDictionary<string,object> to do this:

string propName = "ProductNumber";
dynamic obj = new System.Dynamic.ExpandoObject();
var dict = (IDictionary<string,object>)obj;
dict[propName] = 123;

Doorpost

+1 for at least mentioning that ExpandoObject is IDictionary<string,object> underneath. See docs – Eye