Dynamically adding properties to an ExpandoObject

Question

I would like to dynamically add properties to a ExpandoObject at runtime. So for example to add a string property call NewProp I would like to write something like

var x = new ExpandoObject();
x.AddProperty("NewProp", System.String);

Is this easily possible?

Answer 1

dynamic x = new ExpandoObject();
x.NewProp = string.Empty;

Alternatively:

var x = new ExpandoObject() as IDictionary<string, Object>;
x.Add("NewProp", string.Empty);

Answer 2

As explained here by Filip - http://www.filipekberg.se/2011/10/02/adding-properties-and-methods-to-an-expandoobject-dynamicly/

You can add a method too at runtime.

x.Add("Shout", new Action(() => { Console.WriteLine("Hellooo!!!"); }));
x.Shout();

Answer 3

Here is a sample helper class which converts an Object and returns an Expando with all public properties of the given object.

    public static class dynamicHelper
        {
            public static ExpandoObject convertToExpando(object obj)
            {
                //Get Properties Using Reflections
                BindingFlags flags = BindingFlags.Public | BindingFlags.Instance;
                PropertyInfo[] properties = obj.GetType().GetProperties(flags);

                //Add Them to a new Expando
                ExpandoObject expando = new ExpandoObject();
                foreach (PropertyInfo property in properties)
                {
                    AddProperty(expando, property.Name, property.GetValue(obj));
                }

                return expando;
            }

            public static void AddProperty(ExpandoObject expando, string propertyName, object propertyValue)
            {
                //Take use of the IDictionary implementation
                var expandoDict = expando as IDictionary;
                if (expandoDict.ContainsKey(propertyName))
                    expandoDict[propertyName] = propertyValue;
                else
                    expandoDict.Add(propertyName, propertyValue);
            }
        }

Usage:

//Create Dynamic Object
dynamic expandoObj= dynamicHelper.convertToExpando(myObject);

//Add Custom Properties
dynamicHelper.AddProperty(expandoObj, "dynamicKey", "Some Value");

Answer 4

i think this add new property in desired type without having to set a primitive value, like when property defined in class definition

var x = new ExpandoObject();
x.NewProp = default(string)