How do I check type of dynamic datatype at runtime?

Question

In my ASP.NET website, I have a method that returns a value of type dynamic. This method, depending on certain criteria and results, will then either return a Boolean value or SortedList.

There is too much code to paste, but for example:

public dynamic ReturnThis(dynamic value)
{
    if(someConditionIsMet)
    {
        value = true;
    }
    else
    {
        value = new List<String>().Add(new Person() { Name = "Travis" });
    }

    return value;
}

My problem is, I would like to determine the datatype of value after calling this method before acting on or reading its data. But I am unsure how to check what type dynamic value is. How can I do this?

possible duplicate of [get the Type for a object declared dynamic](http://stackoverflow.com/questions/7362532/get-the-type-for-a-object-declared-dynamic) — Erik Philips, Apr 17 '14 at 20:57

score 32 · Answer 1 · edited Oct 11 '16 at 21:45

Both solutions are working for me. In the documentation Smeegs linked to, the is keyword was mentioned. And I came up with a slightly more readable solution:

if(value is Boolean) { } and if(value is List<Person>) { }

A working test:

using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace ConsoleApplication3348
{
    class Program
    {
        class Person
        {
            string Name = "";
        }

        static void Main(string[] args)
        {

            Console.WriteLine("Assigning List to value");
            dynamic value = new List<Person>();

            if (value is List<Person>)
            {
                Console.WriteLine("value is a list");
            }

            value = false;

            Console.WriteLine("Assigning bool to value");
            if (value is Boolean)
            {
                Console.WriteLine("value is bool");
            }

            Console.Read();
        }
    }
}

score 27 · Accepted Answer · edited Jul 14 '23 at 16:31

27

Just read this on another SO question...hopefully it will do the trick for you:

Type unknown = ((ObjectHandle)value).Unwrap().GetType();

Read and upvote this question for more info: get the Type for a object declared dynamic

edited Jul 14 '23 at 16:31

Loz

118
11

answered Apr 17 '14 at 20:55

Troy Carlson

2,965
19
26

1

not working `{"Cannot convert type 'System.__ComObject' to 'System.Runtime.Remoting.ObjectHandle'"}` dynamic is not castable to `ObjectHandle` – Franck Dec 01 '21 at 14:01

score 21 · Answer 3 · answered Apr 17 '14 at 20:53

21

You should just be able to use GetType(). Like so:

dynamic returnedValue = ReturnThis(value);
var returnType = returnedValue.GetType();

Here is some more information on GetType()

answered Apr 17 '14 at 20:53

Smeegs

9,151
5
42
78

4

According to the other answer, `GetType()` doesn't seem to behave as you're suggesting on `dynamic` types. – mason Apr 17 '14 at 20:56
1

It should for primitive types like `string` and `boolean`, but I'm not 100% – Smeegs Apr 17 '14 at 20:57
2

no, GetType on a dynamic object returns the type dynamic. not helpful. – dr d b karron Mar 06 '19 at 00:03

score 7 · Answer 4 · answered Jun 10 '20 at 02:23

7

dynamic dyn = 1;
Type t = ((object)dyn).GetType();

Works just fine!

answered Jun 10 '20 at 02:23

Alex Peng

411
5
4

This does not work it return `{Name = "__ComObject" FullName = "System.__ComObject"}` – Franck Dec 01 '21 at 13:54

score 5 · Answer 5 · answered Aug 26 '16 at 10:05

Given a dynamic type:

dynamic dynVar;
Type type;

A merely declared, uninitialized dynamic variable dynVar will throw an exception of Type Microsoft.CSharp.RuntimeBinder.RuntimeBinderException as you are performing runtime binding on a null reference, when performing Type-Reflection via dynVar.GetType().

As pointed out by "Troy Carlson", one may use, the rather slow method via a remoted MarshalByRefObject:
```
 Type type = ((ObjectHandle)dynVar).Unwrap().GetType();
 // > type...is null
```
But a simple null check as for any other type would suffice:
```
 type = dynVar == null ? null : dynVar.GetType();
```
or...
```
 type = dynVar?.GetType();
```

How do I check type of dynamic datatype at runtime?

5 Answers5

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