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Problem with converting variable to Generic class

Posted on 2016-08-29
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Medium Priority
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Last Modified: 2016-09-08
I' trying to achieve the following :
I have an interface with an method in it :

---------------------------------------------------------------------
  public interface IDetailPaneUserControl<T>
  {
    T SelectedItem { get; set; }

    Task LoadView(RadPane paneContainer, T item, PaneUserControl parentPane = null);

    Task LoadView(RadPane paneContainer, Guid? id, PaneUserControl parentPane = null);
  }
---------------------------------------------------------------------

The Implementation is like the following :

---------------------------------------------------------------------
 public class DetailPaneUserControl<T> : PaneUserControl, IDetailPaneUserControl<T>, IMayBeClosed where T : class, IBaseEntity, new()
---------------------------------------------------------------------

This class is inherited in my usercontrol.

However I now need to check of a control is of this type and use a method of it. I cannot give with type, but it have to have the IBaseEntity interface.

---------------------------------------------------------------------
 if (item != null)
            {
                var itemType = item.GetType();
                if (paneContent is IDetailPaneUserControl<itemType>)
                    await ((IDetailPaneUserControl<itemType>) paneContent).LoadView(pane, item);
            }
---------------------------------------------------------------------

The item.GetType() isn't working, saying that itemType is a variable but used as an type.

Any idea's how to get the code working?
0
Comment
Question by:MobileAccess
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11 Comments
 
LVL 45

Expert Comment

by:AndyAinscow
ID: 41775826
Does changing
var itemType = item.GetType();
to
Type itemType = item.GetType();
cure it?
0
 
LVL 20

Expert Comment

by:Daniel Van Der Werken
ID: 41776176
My guess is that this line:

if (paneContent is IDetailPaneUserControl<itemType>)

is expecting an actual Type in <itemType> and what you're passing in is looked upon as a variable.

If AndyAinscow's solution doesn't fix it, I might try something like:

if (paneContent is IDetailPaneUserControl<Item>)

Open in new window


where
Item 

Open in new window

is the true class name of the itemType object. I don't see that in your code.
0
 

Author Comment

by:MobileAccess
ID: 41779526
The problem is that I cannot code it like that. It needs to be specified at runtime. So I can't place the real name (type) of the item. it needs to be dynamic
0
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LVL 45

Expert Comment

by:AndyAinscow
ID: 41779538
Do you mean my suggestion doesn't compile and/or run  ?
0
 
LVL 20

Expert Comment

by:Daniel Van Der Werken
ID: 41781718
I think he means mine, because he can't determine the type until run-time.

I'm thinking of using the Dynamic keyword here, but I don't have an example off hand.  It's just a thought and might not really be correct.
0
 
LVL 45

Expert Comment

by:AndyAinscow
ID: 41781734
It would be nice for the asker to respond so we know which isn't working.  Or close the question if one does actually solve it.
Just guessing is going to waste everyones time.
0
 

Author Comment

by:MobileAccess
ID: 41784298
Andy, I'm sorry, I was sick last week...
Your method I've tried, but the problem stays the same.

Daniel,
Indeed, I do not know the type accept at runtime. I'll take a look at the dynamic approach, haven't used this before...
0
 
LVL 20

Expert Comment

by:Daniel Van Der Werken
ID: 41786076
Apparently, this is doable.

This builds. Not promising you it will run!

        Item item = new Item();
        PaneUserControl paneContent = new PaneUserControl();
        RadPane pane = new RadPane();

        if (item != null)
        {
            var genericItemType = item.GetType();
            var specificItemType = genericItemType.MakeGenericType(item.GetType());
            var list = Activator.CreateInstance(specificItemType);
            if (paneContent is IDetailPaneUserControl<Item>)
            {
                ((IDetailPaneUserControl<Item>)paneContent).LoadView(pane, item);
            }
        }

Open in new window

0
 
LVL 20

Expert Comment

by:Daniel Van Der Werken
ID: 41786088
Ugh. I made a mistake. Let me fix it. That does not answer your question.
0
 
LVL 20

Accepted Solution

by:
Daniel Van Der Werken earned 2000 total points
ID: 41786283
Okay. We can't get rid of using  if (myDetailPanelUserControl is IDetailPaneUserControl<Item>) with the actual type, Item, being used. It just won't work as far as I can tell.

However, we can "dynamically" generate everything, I think.

        Item item = new Item();
        RadPane pane = new RadPane();

        if (item != null)
        {
            Type genericIDetailPaneUserControlType = typeof(IDetailPaneUserControl<>);
            Type[] typeArgs = { item.GetType() };
            Type[] methodTypeArgs = new Type[] { typeof(RadPane), item.GetType(), typeof(PaneUserControl) };

            Type specificicIDetailPaneUserControlType = genericIDetailPaneUserControlType.MakeGenericType(typeArgs);

            var myDetailPanelUserControl = Activator.CreateInstance(specificicIDetailPaneUserControlType);

            MethodInfo methodInfo = myDetailPanelUserControl.GetType().GetMethod("LoadView").MakeGenericMethod(methodTypeArgs);

            methodInfo.Invoke(this, new object[] { pane, item });

        }

Open in new window

0
 

Author Comment

by:MobileAccess
ID: 41788386
Thanks, I'll try this tomorrow :)
0

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