Bob Log III al Tetris

e se fate i bravi metto anche un video…

Nella sua classificazione, Vladimir Jankélévitch distingue la menzogna in base al rapporto che intrattiene con la verità. E dunque c’è la dissimulazione, quando ci si limita a nascondere la verità (Berlusconi ha detto: “Non ho mai voluto candidare veline, non frequento minorenni”). L’alterazione, quando si modifica la natura del vero (Berlusconi ha detto: “Non sapevo che Patrizia fosse una prostituta”). La deformazione, quando se ne ingrandisce o se ne rimpicciolisce il formato (Berlusconi ha detto: “Ho visto tre, quattro volte Noemi e sempre con i genitori”). L’antegoria, quando si dice l’assoluto contrario (Berlusconi ha detto: “Non ho mai pagato una prostituta”). La fabulazione, quando invece di mascherare la verità, la si inventa di sana pianta (Berlusconi ha detto: “C’è un progetto eversivo contro di me”). Leggi tutto qua

Concerto di Carlos Santana a Trieste!
Niente cossa dir, el mato ga ancora zata! =)

Il 14 luglio questo blog aderisce all’appello di Diritto alla Rete contro il Ddl Alfano che imbavaglia la Internet italiana.

I used to get the form validation by hand, with some ugly checks, message boxes, several boolean variables to combine with a lot of operators && and ||. A TOTAL mess.

My target was to provide a simple validation tool that I can spread (by inheritance) to all the forms in a project.
So if your project needs only a simple check for mandatory fields, the solution I found maybe can interest you. If you need something more sofisticated, you can imagine an extension of this solution to suite your needs.

How to get it

In a base form class, the parent of all my forms in the project, get an instance of an ErrorProvider, by putting it into the form. Be sure to have “Modifier” property set to “Protected”.
By default, the form property AutoValidate is set to EnablePreventFocusChange. This way, all the controls fire up Validating Event when it’s time to, and the focus will remain on the control when the validation fails.
In this base form we have to add two methods: ValidateControl and SetValidationHandlerOnControl.
The first one is the method that will handle the validation on the control we need to check.
The second one will add the validation handler to the control.

namespace ValidationTest{
  public partial class MyBaseForm
  {
    ...
    protected void ValidateControlHandler(object sender, CancelEventArgs e)
    {
      // this string will be the tooltip shown when an error appears
      String error = null;
      String textToCheck = String.Empty;

      // we need to be sure that the sender control is
      // of the type System.TextBox
      Type senderType = sender.GetType();
      if (senderType == typeof(TextBox))
        textToCheck = ((TextBox)sender).Text;
      else
        throw new ArgumentException(
  	    "The sender is not a TextBox, but a " + senderType.Name);

      // Mandatory field: if the textToCheck is null or empty, fire up the error
      if (String.IsNullOrEmpty(textToCheck))
      {
        error = "Mandatory field";
        // this CancelEventArgs property locks the pointer over the control
        // until the error disappears
        e.Cancel = true;
      }

      // if there isn't any error, the SetError get a
      // null string and it will not shown.
      // otherwise the SetError will show an icon and a tooltip
      // next to the control that fails the validation
      errorProvider.SetError((Control)sender, error);
    }

    protected void SetValidationHandlerOnControl(Control ctrl)
    {
      // we need to be sure that the sender control
      // is of the type System.TextBox
      Type ctrlType = ctrl.GetType();
      if (ctrlType == typeof(TextBox))
        ctrl.Validating += new CancelEventHandler(this.ValidateControlHandler);
    }
  }
}

Ok, that’s almost done.
Now, if we had a form that inherits from MyBaseForm, we can add the controls we need to validate with a simple call to SetValidationHandlerOnControl.
Let’s consider that we have three TextBoxes: by default they all have property CausesValidation set to true. And let’s have a button that is the default AcceptButton for the form, with the TabIndex property value set to be greater than the TabIndex value of the textboxes.
So we need to call

namespace ValidationTest{
  public partial class MyChildForm : MyBaseForm
  {
    public MyChildForm(){
      InitializeComponent();
      SetValidationHandlerOnControl(this.textBox1);
      SetValidationHandlerOnControl(this.textBox2);
      SetValidationHandlerOnControl(this.textBox3);
    ...
    }
  }
}

that’s it!
Now if we don’t provide any string in one of the textBox, the ErrorProvider will show a little (!) icon near to the textBox, the focus will remain on until the string is null or empty. (See image below)

Get the solution with this example here (18Kb). Hope you’ll find it interesting…
Comment out the article if you like it!

EDIT: corrected a typo. Sorry!

Hello everybody!
One minute ago, I’ve published the RIMA website.
What’s RIMA? It’s a ruby script for archiving emails in Imap server that I wrote.
Check it out! and try it!

Domanda: anche Noemi è truzza?

Indovinate chi è il vero Papi…