C# Type to Generic class

Question

I have a project in MVC C# code-first. I want to pass a type to my method. And my method needs a class to work. But I don't want to pass a class - I want it to be dynamic. Is it possible or not?

Here is my codes;

string item ="PERSON" // item is a parametric I give the table name to get the type of table 
Assembly asm = Assembly.Load("ProjectName");
Type entityType = asm.GetType(String.Format("NameSpace.Model.{0}", item));

 var test = LINQDynamic<>.GetQueryResult(ssa,entityType,ddd); // In LINQDynamic<> I want to use entityType like that LINQDynamic<entityType> but it's not acceptable what can I make the convert type to generic?..Because table name is parametric.Is it possible to convert that type?

public class LINQDynamic<TEntity> where TEntity: class
   {

       public static object GetQueryResult(object pkKey,Type type, params object[] pkKeys)
       {
                     //TODO
       }
    }

Possible duplicate of [How to use reflection to call generic Method?](http://stackoverflow.com/questions/232535/how-to-use-reflection-to-call-generic-method) — sara, Oct 07 '15 at 06:34
Yes may be it's same.But my table name is dynamic.How can I convert or how can I use the reflection for create string table name to real class passing to LINQDynamic. — Bora Oktekin, Oct 09 '15 at 13:03

score 0 · Accepted Answer · answered Oct 07 '15 at 07:13

Reflection example:

public static void Main(string[] args)
{
    Type t = typeof(string);
    Type fooType = typeof(Foo<>);
    Type genericFooType = fooType.MakeGenericType(t);
    object o = Activator.CreateInstance(genericFooType,null);
    MethodInfo method = genericFooType.GetMethod("Bar");
    method.Invoke(o, null);
}

public class Foo<T> where T:class
{
    public void Bar()
    {
        Console.WriteLine ("Calling Bar");
    }
}

score 0 · Answer 2 · answered Oct 07 '15 at 11:52

It seems that you are not using the TEntity in your LINQDynamic class - instead you pass the type as a parameter. This makes the TEntity kind of pointless.

Try:

public class LINQDynamic
{
   public static object GetQueryResult(object pkKey,Type type, params object[] pkKeys)
   {
                 //TODO
   }
}

var test = LINQDynamic.GetQueryResult(ssa,entityType,ddd);

score 0 · Answer 3 · answered Oct 07 '15 at 18:13

I've run into the same problem before. Here's is generally what I do. Keeping winding your way up the call stack in your code until you get to a point where you can describe what's happening with an interface and not a generic, i.e.; IEnumerable GetResults(string item).

Then, code gen the contents of the method (this allows you to keep the generic method call) using Expression Trees, and store the compiled lambda in a static dictionary, where the key is your "item" and the value is Func < IEnumerable < IEntity > >.

Tread lightly though. It's easy to run into issues with multi-threading, memory leaks, and other nasty problems in concurrent and long-running applications like web applications. I would almost recommend you not do it.

score 0 · Answer 4 · edited Apr 06 '21 at 03:14

Adapted the suggestion by singsuyash:

  object[] newobj = { pkey,entityType,pKyes };
            object[] parameters = new object[] { newobj };
            Type t = typeof (string);
            Type linqType = typeof (LinqDynamic<>);
            Type genericLinqType = linqType.MakeGenericType(entityType);
            object o = Activator.CreateInstance(genericLinqType, null);
            MethodInfo method = genericLinqType.GetMethod("GetEntityByPrimaryKey");
            var results = method.Invoke(o, parameters);

C# Type to Generic class

4 Answers4