"alee" wrote:

> I created an object using BindingList<T> for GetObjects() and assigned that
> to a objectBindingSource in a WinForm application.  The ObjectBindingSource
> then
> assigned to a DataGridView.  There was a objectBindingNavigation also on the
> form.  Everything worked as expected when I run the application.  However,
> after inserting
> some new rows, deleting a few rows, and updating yet couple rows, the program
> could not save the resulting datasource.  I had a hard time converting the
> result of the objectBindingSource to a typed DataSet Object table.  Everytime
> I tried to save, the system returned a message stating that the operation
> created duplicated keys in the table and stopped.  It appeared that after
> converting the ObjectBindingSource to a typed dataset, all unchaged rows were
> updated to the dataset as new rows.
>
> I tried to solve the problem with a typed dataset table, it worked fine.  But,
> I can't rewrite all our business objects to use datatables and datarows
> instead of BindingList<object> and objects.
>
> Any suggestions or comments will be greatly appreciated.
>
>

"alee" <u31808@uwe> wrote in message news:6de3a5a9d1d65@uwe...
>I created an object using BindingList<T> for GetObjects() and assigned
>that
> to a objectBindingSource in a WinForm application.  The
> ObjectBindingSource
> then
> assigned to a DataGridView.  There was a objectBindingNavigation also on
> the
> form.  Everything worked as expected when I run the application.
> However,
> after inserting
> some new rows, deleting a few rows, and updating yet couple rows, the
> program
> could not save the resulting datasource.  I had a hard time converting
> the
> result of the objectBindingSource to a typed DataSet Object table.
> Everytime
> I tried to save, the system returned a message stating that the operation
> created duplicated keys in the table and stopped.  It appeared that after
> converting the ObjectBindingSource to a typed dataset, all unchaged rows
> were
> updated to the dataset as new rows.
>
> I tried to solve the problem with a typed dataset table, it worked fine.
> But,
> I can't rewrite all our business objects to use datatables and datarows
> instead of BindingList<object> and objects.
>
> Any suggestions or comments will be greatly appreciated.
>

>>I created an object using BindingList<T> for GetObjects() and assigned
>>that
>[quoted text clipped - 24 lines]
>>
>> Any suggestions or comments will be greatly appreciated.
>
>How are you trying to save the datasource? I am doing the same thing. I am
>not using DataSets, though. I am handling the updates myself, in the class
>for the object. I have a property in my class telling if the row was added
>or modified. When they delete entries from my grid, I am saving those in
>another list. When they hit save, I go through the list and perform the
>inserts and updates, and then do the deletes of the deleted entries. So I
>cache them and do them all at the end.
>
>To set the rowstate, I'm capturing events on the list. My list is defined
>as a BindingList(Of Company).
>
>I figured this out using examples in Brian Noyes' data binding book, and
>Chris Sells' Windows Forms 2.0 book. You don't have either of those, do
>you?
>
>Robin S.

> Robin,
>
> In the WinForm, I used:
>
> private void dockBindingNavigatorSaveItem_Click(object sender, EventArgs
> e)
>       {
>           Dock dock = new Dock();
>           dockBS.EndEdit();
>           dock.UpdateDocks(dockBS.DataSource as BindingList<Dock>);
>       }
>
> and in the Dock class located in a separate DLL, I used:
>
> public void UpdateDocks(BindingList<Dock> docks)
>       {
>           DockandSlipDS.DockTableDataTable table = new
>               DockandSlipDS.DockTableDataTable();
>           foreach( Dock dock in docks)
>           {
>               DockandSlipDS.DockTableRow row = table.NewDockTableRow();
>               row.DockId = dock.DockID;
>               row.Location = dock.Location;
>               row.Electricity = dock.Electricity;
>               row.Water = dock.Water;
>               table.AddDockTableRow( row );
>           }
>           _dockTA.Update( table );
>       }
>
> I guess I need a way to scan through each dock in the docks BindingList
> and
> determine the rowstate.  But I can't find a way to get the rowstate of
> the
> returned.  I don't have the two books you mentioned.  Would it be
> possible
> for you to give me some sample code for adding a rowstate detection event
> inside
> the Dock class to capture any change of rowstate.
>
> Also, can you show me how you keep track of changes using another list
> while
> we are using a BindingSource.  A small example will be greatly
> appreciated.
>
> Cheers,
>
> Alan L.
>

>> Robin,
>>
>[quoted text clipped - 44 lines]
>>
>> Alan L.
>
>There's no such thing as a small example for this stuff.  ;-)
>
>When I first tried to figure out how to make a list of my objects, show
>them in a DataGridView, and support updating, it took me a few days, and
>the help of those two books that I listed. I'm not using table adapters or
>data adapters or datasets to do my updates, I'm handling them myself
>through my business class.
>
>The RowState stuff and methodology for updating, I got from Deborah
>Kurata's "Doing Objects in VB2005". This is the book that taught me how to
>segment my application into 3 layers. I call a Stored Procedure in my
>DataAccess layer to do the updates one object at a time, and have the SP
>check the rowstate to determine which SQL statement in the SP to run, just
>like the data adapters work.
>
>I have a base class from which I derive all of my business layer objects.
>In that class, I have a rowstate enumerator defined with the items
>Unchanged, Added, Deleted, and Modified.
>
>When I load each object, I set it to unchanged, because it hasn't been
>changed yet.
>  me.DataStateChanged(EntityStateEnum.Unchanged)
>
>In my class, in the Set for each property, if the value is changed, I have
>a call:
>    DataStateChanged(EntityStateEnum.Modified)
>
>When they add a new row:
>  DataStateChanged(EntityStateEnum.Added)
>
>When they delete a row, I check and make sure it's not one they have added
>that hasn't been committed yet. If it is, I just remove it. If it's not, I
>save it to a different list (so it doesn't show up in the grid) and do:
>  DataStateChanged(EntityStateEnum.Deleted)
>I process these separately from the add/change list that is displayed to
>the user.
>
>This is the method used to change the state of my object. You have to be
>careful; you can't just arbitrarily change it. For example, if they add a
>row, and then before committing the changes, they change a field in the
>row, you don't want it marked as Modified, you want it to still be marked
>as Added because it hasn't been added yet.
>
>    Protected Sub DataStateChanged(ByVal dataState As EntityStateEnum)
>        'if the state is deleted, mark it as deleted
>        'if they are adding a new one, mark it as an add so
>        '  the stored procedure knows to insert it
>        If dataState = EntityStateEnum.Deleted _
>          Or dataState = EntityStateEnum.Added Then
>            Me.EntityState = dataState
>        End If
>        If Me.EntityState = EntityStateEnum.Unchanged _
>          OrElse dataState = EntityStateEnum.Unchanged Then
>            'they are changing it from add or change or delete back to
>unchanged
>            'or from unchanged to something else
>            Me.EntityState = dataState
>        End If
>    End Sub
>
>A rowstate to expose this property (which is private):
>  Public ReadOnly Property RowState() as EntityStateEnum
>    Get
>      Return Me.EntityState
>    End Get
>  End Property
>
>I hope this helps. If you want to know how to bind a list of objects to a
>DataGridView, and handle the updates w/o casting to a dataset, post your
>e-mail address in some format I can recognize and I'll send you an example.
>It is not trivial the first time you do it. There may also be a way to do
>it better, but I haven't had time to revisit it. It works, and works well,
>and that's all I need.
>
>Robin S.

> Hello Robins,
>
> I already solved the problem.  I literally followed the similar steps you
> took with one exception.  That is I found a good VB.NET article from the
> following URL:
>
> http://blogs.msdn.com/vbteam/archive/2005/04/14/TableAdaptersAndObjects.aspx
>
> Other than that I created one base class to hand entitystate (unchanged,
> modified, added,
> deleted) for all my entity classes to inherit from, and
> one extended BaseList class which extends the BindingList<T> to support
> all
> the
> entity state updates with a built in property DeletedRows, which is
> updated
> by
> the entitystate management code in the base class.
>
> By doing this, the Winform application simply uses the entity class
> object
> without any
> modifications.
>
> Thanks for your suggestions and comments.
>
> Cheers and Best regards,
>
> Alan L.
>
>
> RobinS wrote:
>>> Robin,
>>>
>>[quoted text clipped - 44 lines]
>>>
>>> Alan L.
>>
>>There's no such thing as a small example for this stuff.  ;-)
>>
>>When I first tried to figure out how to make a list of my objects, show
>>them in a DataGridView, and support updating, it took me a few days, and
>>the help of those two books that I listed. I'm not using table adapters
>>or
>>data adapters or datasets to do my updates, I'm handling them myself
>>through my business class.
>>
>>The RowState stuff and methodology for updating, I got from Deborah
>>Kurata's "Doing Objects in VB2005". This is the book that taught me how
>>to
>>segment my application into 3 layers. I call a Stored Procedure in my
>>DataAccess layer to do the updates one object at a time, and have the SP
>>check the rowstate to determine which SQL statement in the SP to run,
>>just
>>like the data adapters work.
>>
>>I have a base class from which I derive all of my business layer objects.
>>In that class, I have a rowstate enumerator defined with the items
>>Unchanged, Added, Deleted, and Modified.
>>
>>When I load each object, I set it to unchanged, because it hasn't been
>>changed yet.
>>  me.DataStateChanged(EntityStateEnum.Unchanged)
>>
>>In my class, in the Set for each property, if the value is changed, I
>>have
>>a call:
>>    DataStateChanged(EntityStateEnum.Modified)
>>
>>When they add a new row:
>>  DataStateChanged(EntityStateEnum.Added)
>>
>>When they delete a row, I check and make sure it's not one they have
>>added
>>that hasn't been committed yet. If it is, I just remove it. If it's not,
>>I
>>save it to a different list (so it doesn't show up in the grid) and do:
>>  DataStateChanged(EntityStateEnum.Deleted)
>>I process these separately from the add/change list that is displayed to
>>the user.
>>
>>This is the method used to change the state of my object. You have to be
>>careful; you can't just arbitrarily change it. For example, if they add a
>>row, and then before committing the changes, they change a field in the
>>row, you don't want it marked as Modified, you want it to still be marked
>>as Added because it hasn't been added yet.
>>
>>    Protected Sub DataStateChanged(ByVal dataState As EntityStateEnum)
>>        'if the state is deleted, mark it as deleted
>>        'if they are adding a new one, mark it as an add so
>>        '  the stored procedure knows to insert it
>>        If dataState = EntityStateEnum.Deleted _
>>          Or dataState = EntityStateEnum.Added Then
>>            Me.EntityState = dataState
>>        End If
>>        If Me.EntityState = EntityStateEnum.Unchanged _
>>          OrElse dataState = EntityStateEnum.Unchanged Then
>>            'they are changing it from add or change or delete back to
>>unchanged
>>            'or from unchanged to something else
>>            Me.EntityState = dataState
>>        End If
>>    End Sub
>>
>>A rowstate to expose this property (which is private):
>>  Public ReadOnly Property RowState() as EntityStateEnum
>>    Get
>>      Return Me.EntityState
>>    End Get
>>  End Property
>>
>>I hope this helps. If you want to know how to bind a list of objects to a
>>DataGridView, and handle the updates w/o casting to a dataset, post your
>>e-mail address in some format I can recognize and I'll send you an
>>example.
>>It is not trivial the first time you do it. There may also be a way to do
>>it better, but I haven't had time to revisit it. It works, and works
>>well,
>>and that's all I need.
>>
>>Robin S.
>
> --
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>