c# - How to prevent error when deleting last DataRow from DataTable bound to DataGridView? -

in winforms application, have following logic triggered button press:

    private void executeselectedconsolecommand()     {         var commandsrow = getcommandsrow();         var consolecommand = getconsolecommand(commandsrow);         task.factory.startnew(() =>         {             var runningcommandrow =                   runtimedataset.runningcommands.addrunningcommandsrow(guid.newguid(),                   consolecommand.onelinedescription);              consolecommand.run(null);              runningcommandrow.delete();         });     } 

a bindingsource used let datagridview automatically update itself.

as of now, without following hack, error saying the "index 0 invalid".

        // prevents error when removing last row data bound datagridview         var placeholder = runtimedataset                              .runningcommands                              .addrunningcommandsrow(guid.newguid(), "placeholder"); 

with above code, causes there @ least 1 row in datagridview, works fine.

how fix this?

note: seems many others have run into, web searches have failed..

i have had same problem. after trial , error have discovered have handle several events of datagridview make go away, , requires error ignoring. don't remeber precisely have done circumvent error think following snippets may offer insight (explanations in comments):

remove row:

//when remove row has been added, not commited return function //run update function if row commited (databound) private void dgvtest_rowsremoved(object sender, datagridviewrowsremovedeventargs e) {     if (_lastdatarow == null || _lastdatarow.rowstate == datarowstate.added)         return;     updaterowtodatabase(); } 

row validating:

//i got kind of index not valid or other index errors //rowvalidating fired when entering row , when leaving //in case there no point in validating on row enter private void dgvtest_rowvalidating(object sender, datagridviewcellcanceleventargs e)    { if (disposing)      return; if (!dgvtest.iscurrentrowdirty) {      return;     } try { var v = dgvtest.rows[e.rowindex].databounditem; } catch { return; } } 

data error:

//i had trap errors , change things accordingly private void dgvtest_dataerror(object sender, datagridviewdataerroreventargs e) {         if (e.exception.message.contains("index") && e.exception.message.contains("does not have value")) {             //when editing new row, after first 1 throws error             //cancel , reset allow user make desired changes             bindingsource.canceledit();             bindingsource.endedit();             bindingsource.allownew = false;             bindingsource.allownew = true;             e.cancel = true;             dgvtest.visible = false;             dgvtest.visible = true;         }     } 

row enter:

 //some problemes occured when entering new row  //this resets bindingsource's allownew property user may input new data  private void dgvtest_rowenter(object sender, datagridviewcelleventargs e) {             if (!_loaded)                 return;             if (e.rowindex == dgvtest.newrowindex)                 if (string.isnullorwhitespace(dgvtest.rows[e.rowindex == 0 ? e.rowindex : e.rowindex - 1].cells[_idcolumn].value.tostringsafe())) {                     bindingsource.canceledit();                     bindingsource.allownew = false;                     bindingsource.allownew = true;                 }         } 

hope helps!