Validate after user enter value and prevent switching next control

Thanks for the reply. Really useful topics!
I'm handling the "ValidatingEditor" event.
Inside I'm doing:
var myrule = (from rule in Validator.RuleSet.RegisteredRules
                         where rule.Id == "RuleRequiredField for Document.DocumentType"
                         select rule).FirstOrDefault();
var result = myrule.Validate(e.Value);
It always gives me false even if it is filled.
And if the result is false, how can avoid leaving the cell?
Please check attachment.
Many thanks!

If I use the recommended code from this help article, the validation works as expected:

C#
var result2 = Validator.RuleSet.ValidateTarget(View.ObjectSpace, e.Value, "Save");  

Thanks for the reply Dennis.
What about prevent switching to next control until user chooses a valid option? Is it possible?

If you can additionally handle other GridView events as well as events of the corresponding repository item here. Please refer to the How to force validation in repositoryitemgridlookupedit ticket for more details.
In general, this part is not specific to XAF, and you can use any other solutions recommended for the grid control. Do not hesitate to contact our XtraGrid team or check the grid control's documentation in case of any further difficulties here.

Thanks for response!
I think I almost got it but still got some problems. I'm using enter to move to next column.
With tab key everything works fine but not with enter.
If I have no value selected with tab key it won't leave field until it's filled. With enter it leaves field and fills with the first value without selecting even one.
Thanks!

Thanks for the update. I am working on your issue and will get back to you as soon as I can.

Joao, I found your current approach a bit unusual, especially regarding using the SendKeys function in the routine that handles the Enter key (see the attached screenshot).
Since this task is unrelated to XAF itself, I have created a separate ticket on the XtraGrid product as I suggested to you in my previous reply: How do I stop moving to the next control or column when pressing Enter and Tab keys if the currently focused cell is invalid. Feel free to reactivate this ticket if you experience any difficulties applying the solution suggested by our XtraGrid team in XAF. You may also update the ticket I created to describe your business requirements in greater detail. This information will help us provide you with a solution faster.

Hi thanks a lot for the effort that you guys made!
I've tried the solution works fine with strings but with collections it appears some exclamations points. Don't quite understand what is that.
Where can I read more about it?
Thanks again!

I reviewed your project but it is not clear what you mean by "collections".
It seems that you added the 'Status' property that is shown with the help of the LookupEdit in a common XAF application. The LookupEdit class is designed to be used in a GridListEditor class and cannot be used directly with GridControl.
To provide a capability to edit a reference property, create a RepositoryItemLookUpEdit object and assign it to the GridColumn.ColumnEdit property as it is demonstrated in the Q378130.zip file attached to the How do I stop moving to the next control or column when pressing Enter and Tab keys if the currently focused cell is invalid ticket:

Code
DevExpress.XtraEditors.Repository.RepositoryItemLookUpEdit lookup = new DevExpress.XtraEditors.Repository.RepositoryItemLookUpEdit();  
lookup.DataSource = CreateDataSource();  
lookup.DisplayMember = "Name";  
lookup.ValueMember = "ID";  
gridView1.Columns["ID"].ColumnEdit = lookup;  

Don't hesitate to write to me if I misunderstand your needs.
Our team is dedicated to addressing all your concerns. For quick and efficient responses, we kindly request that future messages cover one issue at a time. Your time and cooperation are appreciated.