forcing Validation; WPF, DataGrid, ObservableCollection

Question

I have a WPF DataGrid. I read a csv file and build an ObservableCollection of objects. I set the DataGrid.ItemsSource to the Collection. I would like to then force a RowValidation on every row in the DataGrid. If I, playing user, edit a cell, the RowValidation fires, all is well. But the Validation does not fire on the initial load. Is there some way I can call ??ValidateRow?? on a row? on every row? (C#, WPF, VS2008, etc)

You can try `row.BindingGroup.ValidateWithoutUpdate()` https://stackoverflow.com/a/42476772/2122718 — marbel82, Sep 16 '20 at 13:30

score 2 · Answer 1 · answered Jun 16 '09 at 12:17

For your bindings, set the UpdateSourceTrigger to property changed, and then put your validation rules inside that. The default update source trigger is Lost Focus.

  <Binding Path="Name" UpdateSourceTrigger="PropertyChanged">
            <Binding.ValidationRules>
                <ExceptionValidationRule />
            </Binding.ValidationRules>
        </Binding>

Also, for another good solution, have a look here

http://www.codeproject.com/KB/WPF/wpfvalidation.aspx

Paul builds a custom error provider, like

You can call the Validate() method on the ErrorProvider to force validation, and check if the controls are valid

score 1 · Answer 2 · answered Dec 16 '11 at 18:25

You will need to setup a RowValidationRule and set the ValidationStep="ConvertedProposedValue" if you want it to validate after initial loading of the ObservableCollection

        <DataGrid Name="dgCsvObjects"
            ItemsSource="{Binding Path=CsvObjects}"
            AutoGenerateColumns="False">
            <DataGrid.RowValidationRules>
                <Validation:MyObjectValidationRule ValidationStep="ConvertedProposedValue" />
            </DataGrid.RowValidationRules>
            <DataGrid.Columns>
                <DataGridTextColumn Header="Property1" Binding="{Binding Path=Property1}"  />
                <DataGridTextColumn Header="Property2" Binding="{Binding Path=Property2}"  />
                <DataGridTextColumn Header="Property3" Binding="{Binding Path=Property3}"  />
                <DataGridTextColumn Header="Property4" Binding="{Binding Path=Property4}"  />
            </DataGrid.Columns>
        </DataGrid>

forcing Validation; WPF, DataGrid, ObservableCollection

2 Answers2