R – Silverlight 3 validation DataForm with templates

dataformsilverlight-3.0validation

I have a SL3 application in which I'm using DataForm for my data entry. I want my form to look in the way I like it, so, I use <dataControls:DataForm.EditTemplate> and inside the template I have my good looking form design.

the main issue is, inside the template I have to use normal controls (like TextBox) instead of the "field" controls (like DataFormTextField). they both work almost the same with the big difference when it gets to validation.

if I throw an exception in the setter of the property to which they are bound, they both show the proper red sign and error, but if I decorate the property by validation attributes (for example [Required(ErrorMessage = "can't be empty!")]), only the DataFormTextField control and not the TextBox control will show the error. in both cases my ErrorSummary control has the error in its collection, so I can see the error is being taken into account…

Any help is appreciated.

Best Answer

Are you using the template field?

   <df:DataFormTemplateField FieldLabelContent="Year"> 
      <df:DataFormTemplateField.DisplayTemplate> 
        <DataTemplate> 
          <TextBox Text="{Binding Year}" HorizontalAlignment="Left" /> 
        </DataTemplate> 
      </df:DataFormTemplateField.DisplayTemplate> 
      <df:DataFormTemplateField.EditTemplate> 
        <DataTemplate> 
          <TextBox Text="{Binding Year}" HorizontalAlignment="Left" /> 
        </DataTemplate> 
      </df:DataFormTemplateField.EditTemplate> 
    </df:DataFormTemplateField>

Related Solutions

R – Silverlight 3 – dataform errorsummary with RIA validation

Visual Studio breaks because it sees an error it believes is not handled. If you just continue the program the error will be handled and the failed validation will show as expected.

You can tell VS not to stop on an user unhanded ValidationException using the Debug/Exceptions dialog in VS.

R – Silverlight 3 Validation using Prism

There aren't any from Microsoft at present, but I'll pass this one onto the PRISM team tomorrow to see if we can get a basic Form Validation example inside the next rev of PRISM.

That being said, you can put a validator per Form that essentially validates each field (semantic and/or syntax validation) and should all pass, will return a true/false state.

A way I typically do this is I attach a "CanSave" method to my Commands ie:

SaveOrderCommand = new DelegateCommand<object>(this.Save, this.CanSave);

private bool CanSave(object arg)
{
     return this.errors.Count == 0 && this.Quantity > 0;
}

Then in the this.CanSave, i then put either the basic validation inside this codebase, or I call a bunch of other validators depending on the context - some would be shared across all modules (ie IsEmailValid would be one Validator i place in my Infrastructure Module as a singleton and pass in my string, it would then true/false as a result). Once they all pass, ensure CanSave returns true. If they fail, the CanSave will return False.

Now if they fail and you want to trigger a friendly reminder to the user that its failed theres a number of techniques you can use here. I've typically flagged the said control at validation as being "failed".. (i wrote my own mind you, so up to you which toolkits you could use here - http://www.codeplex.com/SilverlightValidator is a not bad one).

Now, I typically like to do more with Forms that have validation on them by not only highlighting the said control (red box, icon etc) but also explain to the user in more detail whats required of them - thus custom approach is a solution I've opted for.

At the end of the day, you're going to have to do some of the heavy lifting to validate your particular form - but look into ways to re-use validators where they make sense (email, SSN etc are easy ones to re-use).

HTH?

Scott Barnes - Rich Platforms Product Manager - Microsoft.

Best Answer

Related Solutions

R – Silverlight 3 – dataform errorsummary with RIA validation

R – Silverlight 3 Validation using Prism

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