Is there an easy way to merge C# anonymous objects

Question

Let\'s say I have two anonymous objects like this:

var objA = new { test = \"test\", blah = \"blah\" };
var objB = new { foo = \"foo\", bar = \"bar\" };
         


        

Answer 1

Using TypeDescriptor

As mentioned in comments, Luke Foust solution does not work with anonymous types. The cast to Dictionary does not work, I propose to construct the Dictionaries using the TypeDescriptor.GetProperties method:

public static dynamic CombineDynamics(object object1, object object2)
{
  IDictionary dictionary1 = GetKeyValueMap(object1);
  IDictionary dictionary2 = GetKeyValueMap(object2);

  var result = new ExpandoObject();

  var d = result as IDictionary;
  foreach (var pair in dictionary1.Concat(dictionary2))
  {
    d[pair.Key] = pair.Value;
  }

  return result;
}

private static IDictionary GetKeyValueMap(object values)
{
  if (values == null)
  {
    return new Dictionary();
  }

  var map = values as IDictionary;
  if (map == null)
  {
    return map;
  }

  map = new Dictionary();
  foreach (PropertyDescriptor descriptor in TypeDescriptor.GetProperties(values))
  {
    map.Add(descriptor.Name, descriptor.GetValue(values));
  }

  return map;
}

It's now working with anonymous types:

var a = new {foo = "foo"};
var b = new {bar = "bar"};

var c = CombineDynamics(a, b);

string foobar = c.foo + c.bar;

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Notes:

My GetKeyValueMap method is based on the RouteValueDictionary class (System.Web.Routing). I've rewritten it (using ILSpy to disassemble it) because I think that a System.Web class has nothing to do with object merging.