I am creating a control which inherits from the GridView.

I want to have an event that adds a new row to the ODS before the GridView 
binds.

I was thinking of doing this:

private void AttachDataSourceEvent()
{
  ObjectDataSource ds = GetDataSource() as ObjectDataSource;
   if (ds != null) 
      { 
          ds.Selected += new 
ObjectDataSourceStatusEventHandler(this.OnObjectDataSource_Selected); 
      }        
}

protected void OnObjectDataSource_Selected(object sender, 
ObjectDataSourceStatusEventArgs e)
       {
           if (m_addButtonClicked)//Add empty record for the first row to 
the LIST
           {
               List<T> list = (List<T>)e.ReturnValue;
               list.Insert(0, new T());
           }
       }

I think the above code will retrieve the ODS used by the GridView.
However, the code in OnObjectDataSource_Selected was from a Helper Class 
that new what the ODS DataObjectType was.  Now I am having trouble getting 
what the object type used is.  I can get the ODS 
DataObjectTypeName="GridViewHelperTestObjects+TestRow"
but I don't know how to convert this type of syntax to a Type.

Hi Chuck,

Well, that's an interesting idea to add a new record to the data source 
before binding. But I'm still not very clear about the last part of your 
message: where do you get this "GridViewHelperTestObjects+TestRow"? Do you 
have some complete code listing to show the issue? 

On the other hand, I guess why you're adding a new record to the data 
source is that you're trying to let the GridView support inserting new 
record? Feel free to correct me if I'm wrong. If this is the case, actaully 
we can use the footer template to insert a new row into GridView, as this 
article describes:

#Adding a New Row in GridView
http://gridviewguy.com/ArticleDetails.aspx?articleID=98


Regards,
Walter Wang (wawang@online.microsoft.com, remove 'online.')
Microsoft Online Community Support

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Hi Walter,
I don't want to add the row to the footer and I don't care for the numerous 
gridview footer add row techniques.

This DataObjectTypeName="GridViewHelperTestObjects+TestRow"
come from the ObjectDataSource's DataObjectTypeName property.  What I need 
to do is create a new object of this type.  In the VS designer the above text 
is what gets put in the property when I select this object for the 
DataObjectTypeName:

public static class GridViewHelperTestObjects
{
   [DataObject]
   public class GridViewTestDAL
   {
    [DataObjectMethod(DataObjectMethodType.Select, false)]
        public List<TestRow> GetAll()
        {...}
     ....
     }
 
     public class TestRow
    {

        public TestRow()
        { }

     }
}

When you create the ODS you have a couple or items that could be useful:

IDatasource  ObjectDataSources.DataSource ()  
string              ObjectDataSource.TypeName

In the code in my previous post I added the new row to the list but I knew 
the type ahead of time.  Now I can't specify the type ahead of time, but the 
name is in the ODS ObjectDataSource.TypeName.  Is their some way to get the 
Type from the ObjectDataSource.TypeName and then create an object.  I am sure 
that is what the ODS does internally for adding new rows.

http://msdn2.microsoft.com/en-us/library/system.web.ui.webcontrols.objectdatasource.typename.aspx
To create an instance of the object that the ObjectDataSource control binds 
to, the control uses reflection to load the type that is identified by the 
type name at run time. Therefore, the value of the TypeName property can be a 
partially qualified type for code that is located in the Bin or App_Code 
directories or a fully qualified type name for code that is registered in the 
global assembly cache. If you use the global assembly cache, you must add the 
appropriate reference to the assemblies section of the Machine.config or 
Web.config fil

Well here is what I came up with for my non-Generic method.
Let me know if their is a better way.

protected void OnObjectDataSource_Selected(object sender, 
ObjectDataSourceStatusEventArgs e)
        {
            if (m_AddingInsertRow)//Add empty record for the first row to 
the LIST
            {
                Type typeList = e.ReturnValue.GetType(); //List<T>
                Type typeObj = 
e.ReturnValue.GetType().GetGenericArguments()[0]; //<T>

                object ojb = Activator.CreateInstance(typeObj);  //new T

                // insert the new T into the list by using InvokeMember on 
the List<T>
                object result = null;
                object[] arguments = { 0, ojb };

                result = typeList.InvokeMember("Insert", 
BindingFlags.InvokeMethod, null, e.ReturnValue, arguments);

                //List<T> list = (List<T>)e.ReturnValue;
                //list.Insert(0, new T());
            }
        }

I think your solution should be fine as long as you know before hand that 
the data source is a List<T>. 

On ther other hand, if you use the ObjectDataTypeName string, you can also 
construct an instance of it using following code:

public void AttachDataSourceEvent()
{
    IDataSource ds = GetDataSource();
    ObjectDataSource ods = ds as ObjectDataSource;
    if (ods != null)
    {
        ods.Selected += new 
ObjectDataSourceStatusEventHandler(delegate(object sender, 
ObjectDataSourceStatusEventArgs e) {
            Type typeObj = Type.GetType(ods.DataObjectTypeName);
            object ojb = Activator.CreateInstance(typeObj);
            
            e.ReturnValue.GetType().InvokeMember("Insert", 
BindingFlags.InvokeMethod, null, e.ReturnValue, new object[] { 0, ojb});
        });
    }
}

You still need to assume the list has a well known method to insert the 
data. Not sure if you think it's better or not.

Regards,
Walter Wang (wawang@online.microsoft.com, remove 'online.')
Microsoft Online Community Support

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Walter I seem to have trouble with this (which seems much simpler and more 
direct than e.ReturnValue.GetType().GetGenericArguments()[0] ):

Type typeObj = Type.GetType(ods.DataObjectTypeName); 
In my case

ods.DataObjectTypeName = GridViewHelperTestObjects+TestRow
Type.GetType(ods.DataObjectTypeName) = null

I can't get the type from the ods.DataObjectTypeName

When I do
 Type typeObj = e.ReturnValue.GetType().GetGenericArguments()[0];
I get the type  (Name=TestRow, FullName= GridViewHelperTestObjects+TestRow)

In the immediate window I get:
 Type.GetType("TestRow")
null
 Type.GetType("GridViewHelperTestObjects+TestRow")
null

Hi Chuck,

In my test code, I'm also using an inner class 
(myns.GridViewHelper+Product); so this should not be a problem. 

Anyway, I'm attaching my sample website here for your reference. (You will 
have to use Outlook Express to download the attachment; or you can send me 
an email and I will email the file to you)



Regards,
Walter Wang (wawang@online.microsoft.com, remove 'online.')
Microsoft Online Community Support

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I took your code and added
created a ObjectDataSource1_Selected
in the aspx.cs page

In the event I put:
        ObjectDataSourceView odsv = sender as ObjectDataSourceView;
Type typeObj2 = Type.GetType(odsv.DataObjectTypeName);

The odsv.DataObjectTypeName is identical to what is returned in your inline 
delegate    ods.DataObjectTypeName.

However typeObj2 still comes back null.

Hi Chuck,

My attached website.zip in my last reply should work as is.

As you described, so the issue became we cannot use Type.GetType() to load 
the type correctly. Please try another simpler inner class and use 
Type.GetType on it. My guess is that your DataObject might be in another 
assembly and there's some assembly loading issue.

The difference should not be how we use the delegate or obtaining the 
DataObjectTypeName from ObjectDataSource/ObjectDataSourceView. Following 
code still works on my side:

    public class Class1 : GridView
    {
        public void AttachDataSourceEvent()
        {
            IDataSource ds = GetDataSource();
            ObjectDataSource ods = ds as ObjectDataSource;
            if (ods != null)
            {
                //ods.Selected += new 
ObjectDataSourceStatusEventHandler(delegate(object sender, 
ObjectDataSourceStatusEventArgs e)
                //{
                //    Type typeObj = Type.GetType(ods.DataObjectTypeName);
                //    object ojb = Activator.CreateInstance(typeObj);

                //    e.ReturnValue.GetType().InvokeMember("Insert", 
BindingFlags.InvokeMethod, null, e.ReturnValue, new object[] { 0, ojb });
                //});
                ods.Selected +=new 
ObjectDataSourceStatusEventHandler(ods_Selected);
            }
        }

        void ods_Selected(object sender, ObjectDataSourceStatusEventArgs e)
        {
            ObjectDataSourceView dsv = (ObjectDataSourceView)sender;
            Type typeObj = Type.GetType(dsv.DataObjectTypeName);
            object ojb = Activator.CreateInstance(typeObj);

            e.ReturnValue.GetType().InvokeMember("Insert", 
BindingFlags.InvokeMethod, null, e.ReturnValue, new object[] { 0, ojb });
        }
    }


Regards,
Walter Wang (wawang@online.microsoft.com, remove 'online.')
Microsoft Online Community Support

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Hi Chuck,

How's the status of this post?


Regards,
Walter Wang (wawang@online.microsoft.com, remove 'online.')
Microsoft Online Community Support

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*** Sent via Developersdex http://www.developersdex.com ***

I'll just leave it as:
Type typeObj = 
e.ReturnValue.GetType().GetGenericArguments()[0]; //<T> 

I did some searching on Type.MakeGenericType
but didn't get anywhere.

Hi Chuck,

Since my code seems cannot reproduce the issue you mentioned, I'm wondering 
if you could create a reproducible project and send it to me? Thanks.


Regards,
Walter Wang (wawang@online.microsoft.com, remove 'online.')
Microsoft Online Community Support

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Hi Chuck,

Thank you for your code. I've done some research and found the difference 
between your code and mine is that the data object type is in a different 
assembly other than the GridView's assembly, therefore a simple type name 
string without assembly name will not load it.

The fix is to supply the assembly name when you declare ObjectDataSource:

    <asp:ObjectDataSource ID="odsForGrid" runat="server" 
DataObjectTypeName="GridViewHelperTestObjects+TestRow,__code"


(__code is the special assembly name for code in App_Code)



Hope this helps.


Regards,
Walter Wang (wawang@online.microsoft.com, remove 'online.')
Microsoft Online Community Support

==================================================
When responding to posts, please "Reply to Group" via your newsreader so
that others may learn and benefit from your issue.
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