Walkthrough: Retrieving Dialog Box Information Collectively Using Objects

Walkthrough: Retrieving Dialog Box ...

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Microsoft Visual Studio 2008/.NET Framework 3.5

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Windows Forms Programming

Walkthrough: Retrieving Dialog Box Information Collectively Using Objects

Updated: October 2008

Most Windows Forms dialog boxes have properties that expose information to the parent form. Rather than create multiple properties, you can expose a group of related data through a single dialog box property by creating a class object that stores all of the information needed by the parent form.

The following walkthrough creates a dialog box that exposes a UserInformation property containing name and e-mail address data, which is available to the parent form even after the dialog box is closed.

To create a dialog box that will expose its data through an object

In Visual Studio, create a new Windows Forms project called DialogBoxObjects. For more information, see How to: Create a Windows Application Project.
Add a new Form to the project and name it InformationForm. For more information, see How to: Add Windows Forms to a Project.
From the Toolbox, drag a TableLayoutPanel onto the InformationForm form.
Use the smart tag that appears as an arrow next to the TableLayoutPanel control to add a third row to the table.
Use the mouse to resize the rows so that all three rows are equal.
From the Toolbox, drag a Label to each table cell in the first column.
Set the Name property of the Label controls to firstNameLabel, lastNameLabel, and emailLabel.
Set the Text property of the controls to First Name, Last Name, and Email.
From the Toolbox, drag a TextBox to each cell in the second column.
Set the Name property of the TextBox controls to firstNameText, lastNameText, and emailText.
From the Toolbox, drag a Button control onto the form.
Set the Name property of the Button to closeFormButton.
Set the Text property of the Button to OK.
Add a new class file named UserInformation to the project.
For a C# project, add the public qualifier to the class definition to make this class visible outside of its namespace.

In the UserInformation class, add property definitions for the FirstName, LastName and EmailAddress properties. When you are finished, the code should look like this:

Visual Basic

Public Class UserInformation
    Private _FirstName As String = ""
    Private _LastName As String = ""
    Private _EmailAddress As String = ""

    Public Property FirstName() As String
        Get
            Return _FirstName
        End Get
        Set(ByVal value As String)
            _FirstName = value
        End Set
    End Property


    Public Property LastName() As String
        Get
            Return _LastName
        End Get
        Set(ByVal value As String)
            _LastName = value
        End Set
    End Property


    Public Property EmailAddress() As String
        Get
            Return _EmailAddress
        End Get
        Set(ByVal value As String)
            _EmailAddress = value
        End Set
    End Property
End Class

using System;
using System.Collections.Generic;
using System.Text;

namespace DialogBoxObjects
{
    public class UserInformation
    {
        private string _firstName = "";
        private string _lastName = "";
        private string _emailAddress = "";

        public string FirstName
        {
            get
            {
                return (_firstName);
            }
            set
            {
                _firstName = value;
            }
        }

        public string LastName
        {
            get
            {
                return (_lastName);
            }
            set
            {
                _lastName = value;
            }
        }

        public string EmailAddress
        {
            get
            {
                return (_emailAddress);
            }
            set
            {
                _emailAddress = value;
            }
        }
    }
}

Visual C++

using namespace System;
using namespace System::Collections::Generic;
using namespace System::Text;

namespace DialogBoxObjects
{
    public ref class UserInformation
    {
    public:
        UserInformation()
        {
            firstNameValue = "";
            lastNameValue = "";
            emailAddressValue = "";
        }
    private:
        String^ firstNameValue;
    private:
        String^ lastNameValue;
    private:
        String^ emailAddressValue;
    public:
        property String^ FirstName
        {
            String^ get()
            {
                return firstNameValue;
            }
            void set( String^ value )
            {
                firstNameValue = value;
            }
        }
    public:
        property String^ LastName
        {
            String^ get()
            {
                return lastNameValue;
            }
            void set( String^ value )
            {
                lastNameValue = value;
            }
        }
    public:
        property String^ EmailAddress
        {
            String^ get()
            {
                return emailAddressValue;
            }
            void set( String^ value )
            {
                emailAddressValue = value;
            }
        }
    };
}

In Solution Explorer, right-click InformationForm and select View Code.

In the code-behind page for InformationForm, enter the following code in the InformationForm class to add a UserInformation property.

Visual Basic

Private _UI As New UserInformation()

Public ReadOnly Property UserInformation() As UserInformation
    Get
        Return _UI
    End Get
End Property

UserInformation _ui = new UserInformation();

public UserInformation UserInformation
{
    get
    {
        return (_ui);
    }
}

Visual C++

    DialogBoxObjects::UserInformation^ userInformation;

public:
    property DialogBoxObjects::UserInformation^ UserInformation
    {
        DialogBoxObjects::UserInformation^ get()
        {
            return this->userInformation;
        }
    }

In the InformationForm class, add a Validated event handler for each of the TextBox controls.

In the event handler code, update the corresponding property of the UserInformation class whenever the TextBox value changes, as shown in the following code. For more information, see How to: Create Event Handlers Using the Designer.

Visual Basic

Private Sub FirstNameText_Validated(ByVal sender As Object, ByVal e As EventArgs) Handles FirstNameText.Validated
    Dim FirstNameTemp As String = FirstNameText.Text.Trim()
    If FirstNameText.Text.Trim().Length > 0 Then
        _UI.FirstName = FirstNameTemp
    End If
End Sub

Private Sub LastNameText_Validated(ByVal sender As Object, ByVal e As EventArgs) Handles LastNameText.Validated
    Dim LastNameTemp As String = LastNameText.Text.Trim()
    If LastNameText.Text.Trim().Length > 0 Then
        _UI.LastName = LastNameTemp
    End If
End Sub

Private Sub EmailText_Validated(ByVal sender As Object, ByVal e As EventArgs) Handles EmailText.Validated
    Dim EmailTemp As String = EmailText.Text.Trim()
    If EmailTemp.Length > 0 Then
        _UI.EmailAddress = EmailTemp
    End If
End Sub

public InformationForm()
{
    InitializeComponent();

    firstNameText.Validated += new EventHandler(firstNameText_Validated);
    lastNameText.Validated += new EventHandler(lastNameText_Validated);
    emailText.Validated += new EventHandler(emailText_Validated);
}

void firstNameText_Validated(object sender, EventArgs e)
{
    string firstNameTemp = firstNameText.Text.Trim();
    if (firstNameText.Text.Trim().Length > 0)
    {
        _ui.FirstName = firstNameTemp;
    }
}

void lastNameText_Validated(object sender, EventArgs e)
{
    string lastNameTemp = lastNameText.Text.Trim();
    if (lastNameText.Text.Trim().Length > 0)
    {
        _ui.LastName = lastNameTemp;
    }
}

void emailText_Validated(object sender, EventArgs e)
{
    string emailTemp = emailText.Text.Trim();
    if (emailTemp.Length > 0)
    {
        _ui.EmailAddress = emailTemp;
    }
}

Visual C++

    private:
        void FirstNameText_Validated(Object^ sender, EventArgs^ e)
        {
            String^ firstName = firstNameText->Text->Trim();
            if (firstName->Length > 0)
            {
                userInformation->FirstName = firstName;
            }
        }

    private:
        void LastNameText_Validated(Object^ sender, EventArgs^ e)
        {
            String^ lastName = lastNameText->Text->Trim();
            if (lastName->Length > 0)
            {
                userInformation->LastName = lastName;
            }
        }

    private:
        void EmailText_Validated(Object^ sender, EventArgs^ e)
        {
            String^ email = emailText->Text->Trim();
            if (email->Length > 0)
            {
                userInformation->EmailAddress = email;
            }
        }

    public:
        InformationForm()
        {
            userInformation = gcnew DialogBoxObjects::UserInformation;

            components = nullptr;
            InitializeComponent();

            firstNameText->Validated += gcnew EventHandler
                (this, &InformationForm::FirstNameText_Validated);
            lastNameText->Validated += gcnew EventHandler(this, 
                &InformationForm::LastNameText_Validated);
            emailText->Validated += gcnew EventHandler(this, 
                &InformationForm::EmailText_Validated);
        }

In the InformationForm class, add a Click event handler for the closeFormButton control.

In the event handler code, validate the input and close the dialog box if the input is valid, as shown in the following code.

Visual Basic

Private Sub closeFormButton_Click(ByVal sender As Object, ByVal e As EventArgs) Handles closeFormButton.Click
    If _UI.FirstName.Length = 0 Then
        MessageBox.Show("First name cannot be zero-length.")
        Exit Sub
    End If
    If _UI.LastName.Length = 0 Then
        MessageBox.Show("Last name cannot be zero-length.")
        Exit Sub
    End If
    If _UI.EmailAddress.Length = 0 Then
        MessageBox.Show("Email address cannot be zero-length.")
        Exit Sub
    End If

    Me.DialogResult = System.Windows.Forms.DialogResult.OK
    Me.Close()
End Sub

private void closeFormButton_Click(object sender, EventArgs e)
{
    if (_ui.FirstName.Length == 0)
    {
        MessageBox.Show("First name cannot be zero-length.");
        return;
    }
    if (_ui.LastName.Length == 0)
    {
        MessageBox.Show("Last name cannot be zero-length.");
        return;
    }
    if (_ui.EmailAddress.Length == 0)
    {
        MessageBox.Show("Email address cannot be zero-length.");
        return;
    }

    this.DialogResult = DialogResult.OK;
    this.Hide();
}

Visual C++

private:
    void CloseFormButton_Click(Object^ sender, EventArgs^ e)
    {
        if (userInformation->FirstName->Length == 0)
        {
            MessageBox::Show("First name cannot be zero-length.");
            return;
        }
        if (userInformation->LastName->Length == 0)
        {
            MessageBox::Show("Last name cannot be zero-length.");
            return;
        }
        if (userInformation->EmailAddress->Length == 0)
        {
            MessageBox::Show("Email address cannot be zero-length.");
            return;
        }

        this->DialogResult = ::DialogResult::OK;
        this->Hide();
    }

To show the dialog box you created and retrieve the data using an object

In Solution Explorer, right-click Form1 and select View Designer.
From the Toolbox, drag a Button control onto the form.
Set the Name property of the Button to showFormButton.
Set the Text property of the Button to Show Form.
Add a Click event handler for the showFormButton control.

In the event handler code, call the dialog box and display the results, as shown in the following code.

Visual Basic

Private Sub showFormButton_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles showFormButton.Click
    Dim InfoForm As New InformationForm()
    Dim dr As DialogResult = InfoForm.ShowDialog()
    If dr = System.Windows.Forms.DialogResult.OK Then
        Dim Txt As String = "First Name: " & InfoForm.UserInformation.FirstName + ControlChars.Cr + ControlChars.Lf
        Txt &= "Last Name: " & InfoForm.UserInformation.LastName + ControlChars.Cr + ControlChars.Lf
        Txt &= "Email Address: " & InfoForm.UserInformation.EmailAddress

        MessageBox.Show(Txt)
    End If

    InfoForm.Dispose()
End Sub

private void showFormButton_Click(object sender, EventArgs e)
{
    InformationForm iForm = new InformationForm();
    DialogResult dr = iForm.ShowDialog();
    if (dr == DialogResult.OK)
    {
        string txt = "First Name: " + iForm.UserInformation.FirstName + "\r\n";
        txt += "Last Name: " + iForm.UserInformation.LastName + "\r\n";
        txt += "Email Address: " + iForm.UserInformation.EmailAddress;

        MessageBox.Show(txt);
    }

    iForm.Dispose();
}

Visual C++

private:
    void ShowFormButton_Click(Object^ sender, EventArgs^ e)
    {
        InformationForm^ informationForm = gcnew InformationForm();
        ::DialogResult dialogResult = informationForm->ShowDialog();
        if (dialogResult == ::DialogResult::OK)
        {
            // Initiate a StringBuilder to build up user information
            StringBuilder^ userData = gcnew StringBuilder("First Name: ");

            // Append the information obtained from the information dialog
            userData->Append(informationForm->UserInformation->FirstName);
            userData->AppendLine();
            userData->Append("Last Name: ");
            userData->Append(informationForm->UserInformation->LastName);
            userData->AppendLine();
            userData->Append("Email Address: ");
            userData->Append(
                informationForm->UserInformation->EmailAddress);

            // Display the information in a message box
            MessageBox::Show(userData->ToString());
        }
    }

Build and run the sample.
When Form1 appears, click the Show Form button.
When InformationForm appears, specify the information and then click OK.
When you click OK, the information that you specified is retrieved from the form, the information is displayed in a message box, and then the form is closed.

Change History

Date	History	Reason
October 2008	Added correct step for closeFormButton Click event handler. Added more steps to clarify instructions.	Content bug fix.

Date

History

Reason

October 2008

Added correct step for closeFormButton Click event handler. Added more steps to clarify instructions.

Content bug fix.

To create a dialog box that will expose its data through an object

To show the dialog box you created and retrieve the data using an object

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