How do I check if a given object is nullable in other words how to implement the following method…
bool IsNullableValueType(object o)
{
...
}
I am looking for nullable value types. I didn't have reference types in mind.
//Note: This is just a sample. The code has been simplified
//to fit in a post.
public class BoolContainer
{
bool? myBool = true;
}
var bc = new BoolContainer();
const BindingFlags bindingFlags = BindingFlags.Public
| BindingFlags.NonPublic
| BindingFlags.Instance
;
object obj;
object o = (object)bc;
foreach (var fieldInfo in o.GetType().GetFields(bindingFlags))
{
obj = (object)fieldInfo.GetValue(o);
}
obj
now refers to an object of type bool
(System.Boolean
) with value equal to true
. What I really wanted was an object of type Nullable<bool>
So now as a work around I decided to check if o is nullable and create a nullable wrapper around obj.
Best Answer
There are two types of nullable -
Nullable<T>
and reference-type.Jon has corrected me that it is hard to get type if boxed, but you can with generics: - so how about below. This is actually testing type
T
, but using theobj
parameter purely for generic type inference (to make it easy to call) - it would work almost identically without theobj
param, though.But this won't work so well if you have already boxed the value to an object variable.
Microsoft documentation: https://docs.microsoft.com/en-us/dotnet/csharp/programming-guide/nullable-types/how-to-identify-a-nullable-type