Re: Linq-SQL canonical editable datagridview sample code

**Marc Gravell** · Jun 27 '08, 07:43 PM

Re: Linq-SQL canonical editable datagridview sample code

Probably you'd need to implement ICancelAddNew, but taking a peek,
BindingList<Tal ready does this, calling RemoveItem correctly...
hmmm... I'll investigate...

**Marc Gravell** · Jun 27 '08, 07:43 PM

Re: Linq-SQL canonical editable datagridview sample code

I've looked at this with LINQ-to-SQL, and I cannot reproduce the
issue; if I add and remove a row (in any combination of immediate and
delayed cancel), then no change is applied to the database.

So: are you using LINQ-to-SQL, or are you using DbLinq? If the latter,
then I suspect it has "issues" noticing this trivial change (trivial
meant in the literal sense - not intended to be patronising).

You might be able to write the list to track insertions itself, but
this should be the job of the data-context. Of course, if this
actually is LINQ-to-SQL, please let me know and I'll retry...

Marc

**Andrus** · Jun 27 '08, 07:43 PM

Re: Linq-SQL canonical editable datagridview sample code

Marc,

>Probably you'd need to implement ICancelAddNew, but taking a peek,
>BindingList<Ta lready does this, calling RemoveItem correctly...

I observed the following:

1. Pressing down arrow in last line of DataGridView calls AddNewCore() which
adds new entity to
DataContext.

2. Pressing Up Arrow doest *not* call RemoveItem. So added fake entity will
me saved on SubmitChanges() .

I'm wondering how Linq-SQL performs this correctly since RemoveItem() is not
called.

I'm using DbLinq but this should not depend on Linq provider.

Andrus.

**Andrus** · Jun 27 '08, 07:43 PM

Re: Linq-SQL canonical editable datagridview sample code

Marc,

I've looked at this with LINQ-to-SQL, and I cannot reproduce the
issue; if I add and remove a row (in any combination of immediate and
delayed cancel), then no change is applied to the database.

I'm planning to fix this in the following way:

1. AddNewCode() assigns new entity to property only, will not add to
DataContext
2. Override ICancelAddNew EndNew() method and add new entity to DataContext
in this method.

Will this work OK ?

Andrus.

**Marc Gravell** · Jun 27 '08, 07:43 PM

Re: Linq-SQL canonical editable datagridview sample code

Probably - but you can't *fully* verify the cancel conditions (the
index etc) since they aren't available as protected... I added
Console.WriteLi ne to RemoveItem, and it seemed to be working fine...

Marc

**Andrus** · Jun 27 '08, 07:43 PM

Re: Linq-SQL canonical editable datagridview sample code

Marc,

Probably - but you can't *fully* verify the cancel conditions (the
index etc) since they aren't available as protected... I added
Console.WriteLi ne to RemoveItem, and it seemed to be working fine...

I found that this occurs only when I move up-down in my
CustomDataGridV iewComBobox column.

Down arrow in this column invokes AddNewCore().
Up arrow does *not* invoke RemoveItem.
Pressing down arrow again causes InvalidOperatio nException in
base.AddNewCore ()

It seems that my combobox column class blocks bindinglist RemoveItem call.
I checked my class overridden methods and it seems that I'm calling base
methods in most cases.
Which combobox columns method calls bindinglist RemoveItem() ?
I implemented combobox column using MSDN sample code.

Any idea how to debug / resolve this issue? Exception which I got is below.

Andrus.

System.InvalidO perationExcepti on was unhandled
Message="Operat ion is not valid due to the current state of the object."
Source="System. Windows.Forms"
StackTrace:
at
System.Windows. Forms.DataGridV iew.DataGridVie wDataConnection .ProcessListCha nged(ListChange dEventArgs
e)
at
System.Windows. Forms.DataGridV iew.DataGridVie wDataConnection .currencyManage r_ListChanged(O bject
sender, ListChangedEven tArgs e)
at
System.Windows. Forms.CurrencyM anager.OnListCh anged(ListChang edEventArgs e)
at System.Windows. Forms.CurrencyM anager.List_Lis tChanged(Object
sender, ListChangedEven tArgs e)
at
System.Componen tModel.BindingL ist`1.OnListCha nged(ListChange dEventArgs e)
at System.Componen tModel.BindingL ist`1.InsertIte m(Int32 index, T
item)
at System.Collecti ons.ObjectModel .Collection`1.A dd(T item)
at System.Componen tModel.BindingL ist`1.AddNewCor e()
at MyAppl.TableLis t`1.AddNewCore( ) in I:\MyAppl\Table List.cs:line 92
at
System.Componen tModel.BindingL ist`1.System.Co mponentModel.IB indingList.AddN ew()
at System.Windows. Forms.CurrencyM anager.AddNew()
at
System.Windows. Forms.DataGridV iew.DataGridVie wDataConnection .AddNew()
at
System.Windows. Forms.DataGridV iew.DataGridVie wDataConnection .OnNewRowNeeded ()
at System.Windows. Forms.DataGridV iew.OnRowEnter( DataGridViewCel l&
dataGridViewCel l, Int32 columnIndex, Int32 rowIndex, Boolean
canCreateNewRow , Boolean validationFailu reOccurred)
at System.Windows. Forms.DataGridV iew.SetCurrentC ellAddressCore( Int32
columnIndex, Int32 rowIndex, Boolean setAnchorCellAd dress, Boolean
validateCurrent Cell, Boolean throughMouseCli ck)
at System.Windows. Forms.DataGridV iew.ProcessDown KeyInternal(Key s
keyData, Boolean& moved)
at System.Windows. Forms.DataGridV iew.ProcessDown Key(Keys keyData)
at
System.Windows. Forms.DataGridV iew.ProcessData GridViewKey(Key EventArgs e)
at System.Windows. Forms.DataGridV iew.ProcessKeyP review(Message& m)
at System.Windows. Forms.Control.P rocessKeyPrevie w(Message& m)
at System.Windows. Forms.Control.P rocessKeyMessag e(Message& m)
at System.Windows. Forms.ComboBox. ChildWndProc(Me ssage& m)
at
System.Windows. Forms.ComboBox. ComboBoxChildNa tiveWindow.WndP roc(Message& m)
at System.Windows. Forms.NativeWin dow.DebuggableC allback(IntPtr hWnd,
Int32 msg, IntPtr wparam, IntPtr lparam)
at System.Windows. Forms.UnsafeNat iveMethods.Disp atchMessageW(MS G&
msg)
at
....

**Marc Gravell** · Jun 27 '08, 07:43 PM

Re: Linq-SQL canonical editable datagridview sample code

Sorry - I don't think I'm going to be able to debug that just from a
stacktrace, and I'm not in a desparate hurry to pick through your full
bespoke code... sorry again...

Marc

**Andrus** · Jun 27 '08, 07:44 PM

Re: Linq-SQL canonical editable datagridview sample code

Marc,

I discovered that this occurs when all following conditions are met:

1. DataGridView contains single row
2. DataGridViewCol umn column is DataGridViewCom boBoxColumn
3. EditMode is EditOnEnter

In this case pressing up arrow in new row does *not* call BindingList
RemoveItem() method.

Is this .NET bug ? Any idea how to fix it ?

Andrus.

**Andrus** · Jun 27 '08, 07:44 PM

Re: Linq-SQL canonical editable datagridview sample code

Following code reproduces DataGridView crash on edit.
Press down arrow, up arrow, down arrow. Exception occurs.

Any idea how to fix ?

Andrus.

using System;
using System.Windows. Forms;
using System.Componen tModel;

class Supplier {
public string Id { get; set; }
}

class Form1 : Form {
[STAThread]
static void Main() {
Application.Run (new Form1());
}

public Form1() {
DataGridView grid = new DataGridView();
// if this line is commented out, all is OK:
grid.EditMode = DataGridViewEdi tMode.EditOnEnt er;
ComboBoxColumn comboBoxColumn = new ComboBoxColumn( );
ComboBoxCell ComboBoxCell = new ComboBoxCell();
comboBoxColumn. CellTemplate = ComboBoxCell;
grid.Columns.Ad d(comboBoxColum n);
BindingList<Sup plierl = new BindingList<Sup plier>();
l.Add(new Supplier());
grid.DataSource = l;
Controls.Add(gr id);
}

class ComboBoxColumn : DataGridViewCom boBoxColumn { }

class ComboBoxCell : DataGridViewCom boBoxCell {
public override Type EditType {
get {
return typeof(ComboBox EditingControl) ;
}
}

}

class ComboBoxEditing Control : ComboBox, IDataGridViewEd itingControl {
protected int rowIndex;
protected DataGridView dataGridView;
protected bool valueChanged = false;

protected override void OnTextChanged(E ventArgs e) {
base.OnTextChan ged(e);
NotifyDataGridV iewOfValueChang e();
}

protected virtual void NotifyDataGridV iewOfValueChang e() {
valueChanged = true;
if (dataGridView != null) {
dataGridView.No tifyCurrentCell Dirty(true);
}
}

public Cursor EditingPanelCur sor {
get {
return Cursors.IBeam;
}
}

public DataGridView EditingControlD ataGridView {
get {
return dataGridView;
}
set {
dataGridView = value;
}
}

public object EditingControlF ormattedValue {
set {
if (value.ToString () != Text) {
Text = value.ToString( );
NotifyDataGridV iewOfValueChang e();
}
}

get {
return Text;
}
}

public object
GetEditingContr olFormattedValu e(DataGridViewD ataErrorContext s
context) {
return Text;
}

public void PrepareEditingC ontrolForEdit(b ool selectAll) { }

public bool RepositionEditi ngControlOnValu eChange {
get {
return false;
}
}

public int EditingControlR owIndex {
get {
return rowIndex;
}

set {
rowIndex = value;
}
}

public void ApplyCellStyleT oEditingControl (DataGridViewCe llStyle
dataGridViewCel lStyle) {
DropDownStyle = ComboBoxStyle.D ropDown;
}

public bool EditingControlW antsInputKey(Ke ys keyData, bool
dataGridViewWan tsInputKey) {
return !dataGridViewWa ntsInputKey;
}

public bool EditingControlV alueChanged {

get {
return valueChanged;
}
set {
valueChanged = value;
}
}
}
}

**Marc Gravell** · Jun 27 '08, 07:44 PM

Re: Linq-SQL canonical editable datagridview sample code

I will look later; I can't promise anything...

**Andrus** · Jun 27 '08, 07:44 PM

Re: Linq-SQL canonical editable datagridview sample code

Marc,

>I will look later; I can't promise anything...

Thank you.

I noticed that if I comment out OnTextChanged() override, exception does not
occur.
However this code is from MSDN sample.

Andrus.

**Marc Gravell** · Jun 27 '08, 07:44 PM

Re: Linq-SQL canonical editable datagridview sample code

Can you (briefly) remind me what the purpose of this custom column is?
I'm reaching the conclusion that (sample or not) trying to implement
this from scratch is going to be hard; can you not just modify the
behavior of the existing control? For example - if you just want to
support up/down keys etc:

class ComboBoxEditing Control : DataGridViewCom boBoxEditingCon trol
{
private void ChangeUpDown(bo ol up)
{
DataGridViewCel l cell =
EditingControlD ataGridView.Cur rentCell;
if (cell == null) return;

int row = cell.RowIndex, col = cell.ColumnInde x;
if (up) row--; else row++;
if (row >= 0 && row < EditingControlD ataGridView.Row Count
&& EditingControlD ataGridView.End Edit())
{
cell = EditingControlD ataGridView.Row s[row].Cells[col];
EditingControlD ataGridView.Cur rentCell = cell;
}
}
public override bool EditingControlW antsInputKey(Ke ys keyData,
bool dataGridViewWan tsInputKey)
{
switch (keyData)
{
case Keys.Up:
BeginInvoke((Me thodInvoker)del egate {
ChangeUpDown(tr ue);
});
return true;
case Keys.Down:
BeginInvoke((Me thodInvoker)del egate {
ChangeUpDown(fa lse);
});
return true;
case Keys.Enter:
BeginInvoke((Me thodInvoker)del egate {
EditingControlD ataGridView.End Edit(); });
return true;
case Keys.Escape:
BeginInvoke((Me thodInvoker)del egate {
EditingControlD ataGridView.Can celEdit(); });
return true;
default:
return base.EditingCon trolWantsInputK ey(keyData,
dataGridViewWan tsInputKey);
}
}
}

**Andrus** · Jun 27 '08, 07:45 PM

Re: Linq-SQL canonical editable datagridview sample code

Marc,

Can you (briefly) remind me what the purpose of this custom column is?

Custom column is used to host virtual foreign key ComboBox.
There may be 50000 customers in customer table. So customer name combobox
data source should be populated dynamically.

I use subclassed DataGridViewCom boBoxCell GetFormattedVal ue() event to
populate combobox datasource
on the fly by calling Combobox datasource bindinglist special
AddIfNotExists( )
method:

protected override object GetFormattedVal ue(object value, int rowIndex, ref
DataGridViewCel lStyle cellStyle,
TypeConverter valueTypeConver ter, TypeConverter formattedValueT ypeConverter,
DataGridViewDat aErrorContexts context) {

ComboBoxColumn comboBoxColumn = OwningColumn as ComboBoxColumn;

comboBoxColumn. PickList.AddIfN otExists(value) ;

return base.GetFormatt edValue(value, rowIndex, ref cellStyle,
valueTypeConver ter, formattedValueT ypeConverter, context);

Custom combobox column implementation is required to allow grid to
host this combobox.
I havent way any other method to allow enter customers by name in grid.

I'm reaching the conclusion that (sample or not) trying to implement
this from scratch is going to be hard;

Probably DataGridView does not call ICancelAddNew.E ndNew() method.
New is remains in uncommited state when AddNewCore() is called. AddNewCore()
throws Invalid Operation exception.
I think there must be simple one line fix which fixes this. Probably
something simple is missing or wrong in custom column implementation. Or is
it possible to call EndNew() method itself from this code ?

can you not just modify the behavior of the existing control?

Should I really add event hander to GetFormattedVal ue() method ? There are
also other methods which needs to be overridden.
Should I try to add event handlers into all places ? MSDN recomments
subclassing and overriding methods as preferred technique for this.

>For example - if you just want to
support up/down keys etc:

The goal is to allow enter data using foreign keys when lookup table is big
and
resides in server.

Andrus.

**Marc Gravell** · Jun 27 '08, 07:45 PM

Re: Linq-SQL canonical editable datagridview sample code

Call me crazy, but a drop-down isn't the first choice I'd use for
this!

I don't know where the problem is; normally, EndNew/CancelNew are used
correctly, but in the code you posted RemoveItem indeed doesn't get
called. I dont' know why.

Re: Linq-SQL canonical editable datagridview sample code

Re: Linq-SQL canonical editable datagridview sample code

Comment

Comment

Comment

Comment

Comment

Comment

Comment

Comment

Comment

Comment

Comment

Comment

Comment

Comment