Master-detail datagridviews : RowValidating wrong behavior when moving focus from detail record to a master record which is not its parent

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in my WinForms app. i have master-detail DataGridViews. i have attached a RowValidating event handler to my detail grid to make some validation and calculations.

RowValidating fires whenever a detail record loses focus.

the problem is:

when i set focus on a detail record (for editing or whatever) , and then move focus to master grid by clicking on a record that is NOT the parent of THAT detail record, this is what happens:

first : RowValidating event for that detail record is fired, which is logical (because it lost focus).

then : RowValidating event for its parent record is fired, which is logical, too (because we moved focus to a new parent) .

and then : RowValiding event for detail record is fired AGAIN !!! RowIndex is the same index of the detail record which previously lost focus, BUT the actual details that are present in the detail grid now are details of the NEW parent (which we clicked on)! THIS IS NOT LOGICAL.

i have tried other events (CellLeave, RowLeave) and they act the same :
detail events are fired first for the detail row which lost focus,
then master events are fired for its parent,
then detail events are fired AGAIN, but for details of the new parent and RowIndex of the old detail record ...

WHY are detail events are fired twice? and why are they using RowIndex of the previous detail record ?

P.S. i downloaded a master-detail DGV demo, and tried the same events, and similar things happened.
DEMO:

Three Master-Details Related Grids on the Same Form[^]

Posted 28-Sep-14 3:01am

nina4ever

Updated 29-Sep-14 22:17pm

v5

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Comments

George Jonsson 30-Sep-14 4:48am

Are you using BindingSource as data source for your DataGridViews or do you connect them directly to DataSet and/or DataTable?
Not sure if it relevant in this case, but I have had problems when not using BindingSource in other cases.

nina4ever 30-Sep-14 5:35am

it is the same code i had previously posted here (the code in the solution not in the question):

http://www.codeproject.com/Questions/817587/Master-detail-datagridview-how-to-insert-master-re?arn=0

it has BindingSource

nina4ever 1-Oct-14 3:00am

thank u for ur concern. i will post the solution ASAP :)

Sinisa Hajnal 30-Sep-14 6:30am

I can only give general advice on this and hope it works :)
1. try step-into debugger option
2. check sender and event parameters to find if you can distinguish between the two validations(maybe as simple as using master id from master and details to exit the event if they differ)

nina4ever 30-Sep-14 6:34am

thank u.

i thought of that, but isn't it a workaround? i mean, is the behavior i am getting logical and correct?

Sinisa Hajnal 30-Sep-14 6:46am

I think it behaves as it should assuming certain behaviour of the master grid - if you are focused on the details grid, upon leaving you get validation. Then your master goes through it's own validation which in turn could trigger bound data validation or set focus to details grid BEFORE finally going to new master and at that point (when new master is set) details grid AGAIN looses focus and triggers validation.

While maybe not logical, I think this could be order of events. Check your master GotFocus / Enter / SelectedIndexChanged events and see if any go (set focus) to details grid

nina4ever 30-Sep-14 7:05am

i did as u suggested, and followed the execution or RowEnter on details DGV. You are right. for some reseason, when i click on master grid, after all master validation is done, detail RowValidating is executed, and then detail RowEnter is executed (even though i am not clicking on detail).. so, since detail is entered, RowValidating fires before detail RowEnter. old details are supposed to be validated since we are entering new details, that's why the RowIndex is the index of old detail row, but unfortunately old details are already removed from detail grid before RowValidating is executed on them, so validation is "accidentally" applied on new details.

to solve this i will do the following in detail RowValidating : compare between MasterGrid.CurrentRow and MasterGrid.Rows[e.RowIndex]. if they are different, then we are in the wrong scenario, so return.

good?

Sinisa Hajnal 30-Sep-14 7:56am

IF it works it is good and there is peace in the world (at least for a moment :) )

nina4ever 30-Sep-14 8:13am

it works. but i got another problem : if i insert invalid data into detail record, then move focus to MASTER grid, detail RowValidating is executed as expected where i set e.Cancel = true, but that doesn't prevent user from leaving detail record! focus moves to master grid and all other events are fired as if nothing happened.
when i return to detail grid to check that invalid value i don't find it, it wasn't accepted anyway.

is it normal that e.Cancel = true doesn't prevent leaving from detail record to master record?

Sinisa Hajnal 30-Sep-14 8:45am

You have to set focus "manually" back to the grid, but that way you risk infinite loop if something else returns the focus to another control.

If you want to prevent user from leaving, you have to use CellValidating event (I'm fairly sure, but not 100%).

Also, calculations not related to validating should be done ...Validated event (Cell or Row).

nina4ever 30-Sep-14 8:52am

sorry, i am performing validation in CellValidating. it couldn't prevent leaving the cell when moving to the parent grid.
calculations are already in CellValidated and RowValidated.

Sinisa Hajnal 1-Oct-14 2:19am

Good work! :) I'm sorry, I don't know why this would happen if you set e.Cancel = True and return there shouldn't be anything afterwards...check grid properties for something like Keep focus on error or move focus after ... or whatever that could cause it. I'm out of ideas :)

nina4ever 1-Oct-14 2:58am

thank u very much for your help. if i come up with something i will post it,
and i will post my solution for the main question ASAP.

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nina4ever · Accepted Answer · 2014-09-30T22:51:00

C#

private void detailGrid_RowValidating(object sender,DataGridViewCellCancelEventARgs e)
{

   string current_parent_row_id =  masterGrid.CurrentRow.Cells["id"].Value.ToString();
   string validated_parent_row_id = detailGrid.Rows[0].Cells["id"].Value.ToString();

   if (current_parent_row_id != validated_parent_row_id) return;

   // validation goes next ...

}