Manage Data in a VB Application (without the Database)

Scott Lysle
Nov 09, 2012
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Introduction

This article provides an approach to building an application that may be used to collect, store, and retrieve data without relying upon a database to get there. If you need to store a limited amount of data, if your users won't be sharing data with other users, and you do not require a full blown relational database on the backend, this might article be of interest.

The article is built around a demonstration project that allows the user to store some information gathered during bird observation; of course the same approach could be used to work with contact information, an inventory, postage stamp collection, coin collections, movie collections, or whatever else you might be interested in keeping tabs on.

Figure 1: Application Main Form

The application provides the following functionality:

Create a bird data file.
Add birds to the bird data file.
Remove birds from the bird data file.
Search for specific birds by name.
Create and edit details about the bird.
- Bird name
- Bird gender
- Bird location
- Bird behavior
- Observation date
- Observation time
- Image of the bird
Save a bird data file.
Reopen a bird data file.
Navigate through all of the birds in the bird data file.
View a list of all birds in the bird data file.

The approaches used within the application are representative of only one way of doing things; as with most things in the .NET world, there are several alternatives and you can modify the code to work with the data using one of the other alternatives if you prefer to do so.

Figure 2: Finding a Bird

Figure 3: Listing All Birds

Getting Started

There is a single solution included with this download, the solution contains a Win Forms project called "BirdWatch_VB"; this project contains three forms (the main form, a search form, and a form used to display the total list of birds), a serializable class called 'BirdData.vb' (used to contain bird related data), and a class entitled, 'FileSerializer.vb' which contains two static methods used to serialize and deserialize the bird data (writing it to and reading it from a file) .

If you open the attached project into Visual Studio 2008; you should see the following in the solution explorer:

Figure 4: Solution Explorer

Code: BirdData.vb

The BirdData class is the container class used to store all of the bird related data used in the application. Whilst this demonstration uses bird data, this could easily be replaced with something more useful to you.

The class begins with the normal and default imports:

Imports System

Imports System.Drawing

Imports System.Collections.Generic

Imports System.Linq

Imports System.Text

The next section contains the class declarations. Note that the class is declared as serializable; the serializable attribute indicates that the class can be serialized.

<Serializable()> _

Public Class BirdData

The region defined in the class declares the member variables used internally by the class; any member variables exposed externally are made accessible through public properties.

#Region "Member Variables"

Private mId As System.Guid

Private mBirdName As String

Private mGender As String

Private mLocation As String

Private mBehaviorObserved As String

Private mDateViewed As DateTime

Private mTimeViewed As DateTime

Private mPicture As Byte()

Private mPictureName As String

#End Region

The next region of code in the class contains the constructors. Two constructors are defined; a default constructor that creates a new instance of the class and assigns it an internal ID (as a Guid). The second constructor accepts a bird name as an argument and, when called, this constructor generates both an ID and assigns the bird name property to the bird name member variable.

#Region "Constructor"

Public Sub New()

mId = Guid.NewGuid()

End Sub

Public Sub New(ByVal birdName)

mId = Guid.NewGuid()

mBirdName = birdName

End Sub

#End Region

The last bit of the code in this class is contained within the properties region; this region contains all of the properties defined to access the member variables. Note that since the ID value is always set by the constructor, the property does not provide a public interface to set the Guid to a new value.

#Region "Properties"

Public ReadOnly Property ID() As Guid

Get

Return mId

End Get

End Property

Public Property BirdName() As String

Get

Return mBirdName

End Get

Set(ByVal value As String)

mBirdName = value

End Set

End Property

Public Property Gender() As String

Get

Return mGender

End Get

Set(ByVal value As String)

mGender = value

End Set

End Property

Public Property Location() As String

Get

Return mLocation

End Get

Set(ByVal value As String)

mLocation = value

End Set

End Property

Public Property BehaviorObserved() As String

Get

Return mBehaviorObserved

End Get

Set(ByVal value As String)

mBehaviorObserved = value

End Set

End Property

Public Property DateViewed() As Date

Get

Return mDateViewed

End Get

Set(ByVal value As Date)

mDateViewed = value

End Set

End Property

Public Property TimeViewed() As Date

Get

Return mTimeViewed

End Get

Set(ByVal value As Date)

mTimeViewed = value

End Set

End Property

Public Property Picture() As Byte()

Get

Return mPicture

End Get

Set(ByVal value As Byte())

mPicture = value

End Set

End Property

Public Property PictureName() As String

Get

Return mPictureName

End Get

Set(ByVal value As String)

mPictureName = value

End Set

End Property

#End Region

End Class

That concludes the description of the 'BirdData' class.

Code: Main Application Form (Form1.vb)

The Bird Tracker main form contains the following controls:

Menu
- File
  - New
  - Open
  - Save
  - Save As
  - Exit
- View
  - List All Birds
Toolbar
- Add Bird
- Remove Bird
- Find Bird
- Save Bird Data
- Navigate to Previous Bird
- Navigate to Next Bird
- Exit Application
Bird name text box control
Bird gender combo box
Bird location multiline text box
Bird Behavior multiline text box
Date of observation date time picker
Time of observation date time picker
Group container
Picture box
Set Picture button

Figure 5: Form1.vb

The class begins with the normal and default imports:

Imports System

Imports System.Collections.Generic

Imports System.ComponentModel

Imports System.Data

Imports System.Drawing

Imports System.Linq

Imports System.Text

Imports System.IO

Imports System.Windows.Forms

The next section contains the class declaration.

''' <summary>

''' A simple project used to maintain data about a

''' collection of birds (could be anything), and to

''' display that data to the user, persist the data,

''' and allow the user to recover and modify the

''' data without using a database.

''' </summary>

Public Class Form1

The region defined in the class declares the member variables used internally by the class; any member variables exposed externally are made accessible through public properties. The comment adjacent to each declaration describes its purpose.

#Region "Variable Declarations"

Private birds As List(Of BirdData) ' a container for the bird collection

Private currentBird As BirdData ' the current bird (displayed)

Private currentFilePath As String ' the path to the bird data file

Private currentPosition As Integer ' the position within the bird list

Private dirtyForm As Boolean ' mark the form dirty when changed

#End Region

The next region of code in the class contains the constructor. Upon initialization, the application creates a new bird data list, creates a new bird data object, sets the date and time picker controls to the current data, sets the current position indicator to zero, and sets the dirty form Boolean to false.

#Region "Constructor"

Private Sub Form1_Load(ByVal sender As System.Object, _

ByVal e As System.EventArgs) Handles MyBase.Load

' create new bird data list

' ready to write data

birds = New List(Of BirdData)()

currentBird = New BirdData()

birds.Add(currentBird)

' set the date time pickers to now

dtpDate.Value = DateTime.Now

dtpTime.Value = DateTime.Now

' init current position to zero

currentPosition = 0

' mark form as not dirty

dirtyForm = False

End Sub

#End Region

The next code region is called 'Housekeeping'. This region contains some basic functionality used to operate the application. The first code section is for the Exit toolbar button click event handler; this function merely calls the exit menu item option's event handler rather than duplicate the code in both functions.

#Region "Housekeeping"

''' <summary>

''' Exit the application

''' </summary>

''' <param name="sender"></param>

''' <param name="e"></param>

''' <remarks></remarks>

Private Sub exitToolStripMenuItem_Click(ByVal sender As System.Object, _

ByVal e As System.EventArgs) _

Handles exitToolStripMenuItem.Click

If dirtyForm = True Then

If MessageBox.Show(Me, "You have not saved the current bird data; " + _

"would you like to save before exiting?", _

"Save Current Data", MessageBoxButtons.YesNo) = _

System.Windows.Forms.DialogResult.Yes Then

saveToolStripMenuItem_Click(Me, New EventArgs())

End If

Else

Application.Exit()

End If

End Sub

The next section of code is the exit menu option's click event handler. This code first checks to see if the form is marked as dirty (based upon user changes made during the operation of the application); if the form is dirty and the user attempts to exist the application, the user will be presented with a message box which will ask them whether or not they wish to exit the application without saving. If the user indicates that they would prefer to save prior to exiting the application, the application will present the save file dialog to the user; otherwise the application will exit.

''' <summary>

''' Exit the application

''' </summary>

''' <param name="sender"></param>

''' <param name="e"></param>

''' <remarks></remarks>

Private Sub tsbExit_Click(ByVal sender As System.Object, _

ByVal e As System.EventArgs) Handles tsbExit.Click

' call the menu function

exitToolStripMenuItem_Click(Me, New EventArgs())

End Sub

The next method is used to clear out all of the information displayed in the main form controls.

''' <summary>

''' Clear all form fields

''' </summary>

Public Sub ClearForm()

dirtyForm = True

txtBirdName.Text = String.Empty

txtLocation.Text = String.Empty

txtBehavior.Text = String.Empty

cboGender.SelectedIndex = -1

dtpDate.Value = DateTime.Now

dtpTime.Value = DateTime.Now

picBird.Image = Nothing

End Sub

The next function contained in the form is used to set the image associated with the current bird. Since we are adding new data to the current instance of bird data, the form is marked as dirty - this will allow the functions used to exit the application to check to see if the current data needs to be saved prior to exiting the application. The function uses the open file dialog to allow the user to set a path to an image file; once a file path is set; the function opens the files, converts it into a byte array and stores it in the current bird data object's image property. The function wraps up by setting the form's image to display selected bird picture.

''' <summary>

''' Load the image into the picture box

''' </summary>

''' <param name="sender"></param>

''' <param name="e"></param>

''' <remarks></remarks>

Private Sub btnSetImage_Click(ByVal sender As System.Object, ByVal e As

System.EventArgs) Handles btnSetImage.Click

dirtyForm = True

Dim imageFilePath As String = String.Empty

Dim OpenFileDialog1 As New OpenFileDialog()

OpenFileDialog1.Title = "Open Image File"

OpenFileDialog1.Filter = "JPEG Documents (*.jpg)|*.jpg|Gif Files|*.gif"

If OpenFileDialog1.ShowDialog() = System.Windows.Forms.DialogResult.Cancel

Then

Return

End If

imageFilePath = OpenFileDialog1.FileName

If String.IsNullOrEmpty(imageFilePath) Then

Return

End If

If System.IO.File.Exists(imageFilePath) = False Then

Return

End If

Try

' convert Image to byte array and save in

Dim fsImage As System.IO.FileStream = Nothing

fsImage = System.IO.File.Open(imageFilePath, FileMode.Open,

FileAccess.Read)

Dim bArrImage(fsImage.Length) As Byte

fsImage.Read(bArrImage, 0, Convert.ToInt32(fsImage.Length))

fsImage.Close()

currentBird.Picture = bArrImage

currentBird.PictureName = imageFilePath

Dim ms As New MemoryStream(bArrImage)

picBird.Image = Image.FromStream(ms)

ms.Dispose()

Catch ex As Exception

MessageBox.Show(ex.Message, "Error Storing Image")

End Try

End Sub

The next function up is used to handle the 'New' menu option's click event; this function begins by checking the dirty form Boolean to see if the current data should be saved prior to starting the new bird data file. If the current form is dirty; the user will be prompted to save the current data, else, a new collection of bird data is created and the form is cleared all of prior entries.

''' <summary>

''' Create a new bird data file

''' </summary>

''' <param name="sender"></param>

''' <param name="e"></param>

''' <remarks></remarks>

Private Sub newToolStripMenuItem_Click(ByVal sender As System.Object, _

ByVal e As System.EventArgs) _

Handles newToolStripMenuItem.Click

If dirtyForm = True Then

If (MessageBox.Show(Me, "You have not saved the current bird data; " + _

"would you like to save before starting a new " + _

"bird database?", "Save Current Data", _

MessageBoxButtons.YesNo) = _

System.Windows.Forms.DialogResult.Yes) Then

saveToolStripMenuItem_Click(Me, New EventArgs())

Else

' discard and start new document

birds = New List(Of BirdData)()

ClearForm()

End If

Else

' start new document

birds = New List(Of BirdData)()

ClearForm()

End If

End Sub

The open file menu option's click event handler is next; this function also checks for a dirty form prior to opening a new bird data file into the application. If the form is not dirty, the application will call the 'Open' function which will in turn allow the user to navigate to and open a file for viewing or edit.

''' <summary>

''' Open an existing bird data file

''' </summary>

''' <param name="sender"></param>

''' <param name="e"></param>

''' <remarks></remarks>

Private Sub openStripMenuItem2_Click(ByVal sender As System.Object, _

ByVal e As System.EventArgs) _

Handles openStripMenuItem2.Click

If dirtyForm = True Then

If (MessageBox.Show(Me, "You have not saved the current bird data; " + _

"would you like to save before opening a different " + _

"bird database?", "Save Current Data", _

MessageBoxButtons.YesNo) = _

System.Windows.Forms.DialogResult.Yes) Then

saveToolStripMenuItem_Click(Me, New EventArgs())

Else

Open()

End If

Else

Open()

End If

End Sub

Next up, the open method uses the open file dialog control to allow the user to navigate to and select a bird data file. Once selected, the file is deserialized into the local bird collection and made available to the display.

''' <summary>

''' Open an existing bird data file

''' </summary>

Public Sub Open()

Dim OpenFileDialog1 As New OpenFileDialog()

OpenFileDialog1.Title = "Open BRD Document"

OpenFileDialog1.Filter = "BRD Documents (*.brd)|*.brd"

If OpenFileDialog1.ShowDialog() = _

System.Windows.Forms.DialogResult.Cancel Then

Return

End If

currentFilePath = OpenFileDialog1.FileName

If String.IsNullOrEmpty(currentFilePath) Then

Return

End If

If System.IO.File.Exists(currentFilePath) = False Then

Return

End If

birds = FileSerializer.Deserialize(currentFilePath)

' Load bird at position zero

If birds.Count <> 0 Then

currentBird = birds.ElementAt(0)

LoadCurrentBird()

dirtyForm = False

End If

End Sub

The save menu option click event handler is up next. This function uses the save file dialog to allow the user to name or set the path to the file. Once the file path is set, the application serializes the data contained in the bird collection, saving it to disk.

''' <summary>

''' Save the existing bird data file

''' </summary>

''' <param name="sender"></param>

''' <param name="e"></param>

''' <remarks></remarks>

Private Sub saveToolStripMenuItem_Click(ByVal sender As System.Object, _

ByVal e As System.EventArgs) _

Handles saveToolStripMenuItem.Click

SaveCurrentBird()

If String.IsNullOrEmpty(currentFilePath) Then

Dim SaveFileDialog1 As New SaveFileDialog()

Try

SaveFileDialog1.Title = "Save BRD Document"

SaveFileDialog1.Filter = "BRD Documents (*.brd)|*.brd"

If SaveFileDialog1.ShowDialog() = _

System.Windows.Forms.DialogResult.Cancel Then

Return

End If

Catch

Return

End Try

currentFilePath = SaveFileDialog1.FileName

End If

If String.IsNullOrEmpty(currentFilePath) Then

MessageBox.Show("File path is not set.", "Save Error")

Return

End If

FileSerializer.Serialize(currentFilePath, birds)

MessageBox.Show("File " + currentFilePath + " saved.", "File Saved")

dirtyForm = False

End Sub

The next bit of code is very similar to save; it allows the user to save the current bird data file to the local hardware using a replacement name.

''' <summary>

''' Save the existing bird data file with

''' a new file name

''' </summary>

''' <param name="sender"></param>

''' <param name="e"></param>

''' <remarks></remarks>

Private Sub saveAsToolStripMenuItem_Click(ByVal sender As System.Object, _

ByVal e As System.EventArgs) _

Handles saveAsToolStripMenuItem.Click

Dim SaveFileDialog1 As New SaveFileDialog()

Try

SaveFileDialog1.Title = "Save BRD Document"

SaveFileDialog1.Filter = "BRD Documents (*.brd)|*.brd"

If SaveFileDialog1.ShowDialog() = _

System.Windows.Forms.DialogResult.Cancel Then

Return

End If

Catch

Return

End Try

currentFilePath = SaveFileDialog1.FileName

If String.IsNullOrEmpty(currentFilePath) Then

Return

End If

FileSerializer.Serialize(currentFilePath, birds)

MessageBox.Show("File " + currentFilePath + " saved.", "File Saved.")

dirtyForm = False

End Sub

The toolbar's save button is up next; it merely calls the save menu item click event to save the bird data file.

''' <summary>

''' Save the existing bird data file

''' </summary>

''' <param name="sender"></param>

''' <param name="e"></param>

''' <remarks></remarks>

Private Sub tsbSave_Click(ByVal sender As System.Object, ByVal e As

System.EventArgs) Handles tsbSave.Click

saveToolStripMenuItem_Click(Me, New EventArgs())

End Sub

The save current bird function is used to set the values of the current bird data object to match the content from the form controls.

''' <summary>

''' Set the current bird values to the form content

''' if the user navigates off the current bird, it will

''' save the content

''' </summary>

Private Sub SaveCurrentBird()

If Not String.IsNullOrEmpty(txtBirdName.Text) Then

Try

currentBird.BirdName = txtBirdName.Text

currentBird.Location = txtLocation.Text

currentBird.BehaviorObserved = txtBehavior.Text

currentBird.Gender = cboGender.Text

currentBird.DateViewed = dtpDate.Value

currentBird.TimeViewed = dtpTime.Value

' bird image byte array is set for current

' bird when image is set

Catch ex As Exception

MessageBox.Show(ex.Message, "Error")

End Try

End If

End Sub

#End Region

The next region is called Bird Data Management; within this section are the methods used to manage the bird data and the bird data collection. The first function contained in this region is used to add a new bird to the collection. The function saves the current bird, creates a new empty bird object, adds the new bird data object to the birds collection, and then marks the form as dirty.

#Region "Bird Data Management"

''' <summary>

''' Add a new bird to the bird data list

''' </summary>

''' <param name="sender"></param>

''' <param name="e"></param>

''' <remarks></remarks>

Private Sub tsbAdd_Click(ByVal sender As System.Object, _

ByVal e As System.EventArgs) _

Handles tsbAdd.Click

SaveCurrentBird()

currentBird = New BirdData()

ClearForm()

birds.Add(currentBird)

dirtyForm = True

End Sub

The next function is used to remove a bird from the collection. After a bird is removed; the current position is updated and the form reloaded with the replacement bird information.

''' <summary>

''' Remove the current bird from the bird

''' from the bird data list

''' </summary>

''' <param name="sender"></param>

''' <param name="e"></param>

''' <remarks></remarks>

Private Sub tsbRemoveBird_Click(ByVal sender As System.Object, _

ByVal e As System.EventArgs) _

Handles tsbRemoveBird.Click

birds.RemoveAt(currentPosition)

If currentPosition = 0 Then

currentPosition += 1

Else

currentPosition -= 1

currentBird = birds(currentPosition)

LoadCurrentBird()

dirtyForm = True

End If

End Sub

The next function is used to support finding a specific bird. When the click event handler is executed, a new instance of the find form (Form3) is created and an event handler for the find form's 'BirdNameUpdated' event is set.

''' <summary>

''' Find a specific bird

''' </summary>

''' <param name="sender"></param>

''' <param name="e"></param>

''' <remarks></remarks>

Private Sub tsbFindBird_Click(ByVal sender As System.Object, _

ByVal e As System.EventArgs) _

Handles tsbFindBird.Click

Dim f As New Form3(birds)

AddHandler f.BirdNameUpdated, AddressOf FindBird

f.Show()

End Sub

The next function up is used to find a specific bird by its name. When find form raises the event indicating that the user wants the bird of a particular name found in the collection, this function will iterate through the collection until the match is found and then it will make that bird the current bird and update the form to display that bird's information.

''' <summary>

''' Bird finder code

''' </summary>

''' <param name="sender"></param>

''' <param name="e"></param>

''' <remarks></remarks>

Private Sub FindBird(ByVal sender As Object, _

ByVal e As BirdNameUpdateEventArgs)

Dim i As Integer

For i = 0 To birds.Count - 1

If birds(i).BirdName = e.BirdName Then

currentBird = birds(i)

LoadCurrentBird()

currentPosition = i

End If

End Sub

The next function is used to display a form containing all of the birds contained in the current bird data list. Form 2 contains a single data grid view control and it accepts a list of bird data as an argument for the constructor. When the form is created and passed a copy of the current bird data, that data is bound to the data grid view control and displayed to the user.

''' <summary>

''' List all of the birds

''' in the bird data file

''' </summary>

''' <param name="sender"></param>

''' <param name="e"></param>

''' <remarks></remarks>

Private Sub listAllBirdsToolStripMenuItem_Click(ByVal sender As System.Object, _

ByVal e As System.EventArgs) _

Handles

listAllBirdsToolStripMenuItem.Click

Dim f As New Form2(birds)

f.Show()

End Sub

The next function is called whenever the current bird is changed. It reloads all of the form controls from the current bird object.

''' <summary>

''' Load the current bird into the form

''' </summary>

Private Sub LoadCurrentBird()

Try

txtBirdName.Text = currentBird.BirdName

txtLocation.Text = currentBird.Location

txtBehavior.Text = currentBird.BehaviorObserved

Catch

End Try

Try

cboGender.Text = currentBird.Gender

Catch

End Try

Try

dtpDate.Value = currentBird.DateViewed

Catch

End Try

Try

dtpTime.Value = currentBird.TimeViewed

Catch

End Try

Try

If currentBird.Picture IsNot Nothing Then

Dim ms As New MemoryStream(currentBird.Picture)

picBird.Image = Image.FromStream(ms)

ms.Dispose()

Else

picBird.Image = Nothing

End If

Catch

picBird.Image = Nothing

End Try

End Sub

#End Region

The next region contained within this class contains two functions used to control navigation forwards and backwards through the bird data list. In either case, the current bird is saved by calling the 'SaveCurrentBird' function. After the current bird is saved locally, the position is checked to see if it is at the bottom or top limit and if possible, the position is incremented or decremented. Once the current position is updated, the current bird data is set to the bird data at the updated position and for the form reloaded.

#Region "Navigation"

''' <summary>

''' Navigate back to the previous record

''' if possible

''' </summary>

''' <param name="sender"></param>

''' <param name="e"></param>

''' <remarks></remarks>

Private Sub tsbNavBack_Click(ByVal sender As System.Object, _

ByVal e As System.EventArgs) _

Handles tsbNavBack.Click

SaveCurrentBird()

If currentPosition <> 0 Then

currentPosition -= 1

currentBird = birds(currentPosition)

LoadCurrentBird()

End If

End Sub

''' <summary>

''' Navigate to the next bird

''' record if possible

''' </summary>

''' <param name="sender"></param>

''' <param name="e"></param>

''' <remarks></remarks>

Private Sub tsbNavForward_Click(ByVal sender As System.Object, _

ByVal e As System.EventArgs) _

Handles tsbNavForward.Click

SaveCurrentBird()

If currentPosition < (birds.Count - 1) Then

currentPosition += 1

currentBird = birds(currentPosition)

LoadCurrentBird()

End If

End Sub

#End Region

The last region of code in this class is used to mark the form as dirty in response to changes. Note that, rather than using the value changed events to set the form dirty, other events such as the text box control's key press event were used to provide an indication as to whether or not something was changed. The reason being that, if one were to open a bird data file and navigate through the list, the values would change and the form would be marked as dirty even though in reality no changes took place.

#Region "Dirty Form"

''' <summary>

''' Dirty the form whenever the user

''' types into the bird name textbox

''' </summary>

''' <param name="sender"></param>

''' <param name="e"></param>

''' <remarks></remarks>

Private Sub txtBirdName_KeyPress(ByVal sender As System.Object, _

ByVal e As

System.Windows.Forms.KeyPressEventArgs) _

Handles txtBirdName.KeyPress

dirtyForm = True

End Sub

''' <summary>

''' Dirty the form if the user clicks

''' on the gender combo box

''' </summary>

''' <param name="sender"></param>

''' <param name="e"></param>

''' <remarks></remarks>

Private Sub cboGender_MouseClick(ByVal sender As System.Object, _

ByVal e As System.Windows.Forms.MouseEventArgs)

Handles cboGender.MouseClick

dirtyForm = True

End Sub

''' <summary>

''' Dirty the form whenever the user

''' types into the bird location textbox

''' </summary>

''' <param name="sender"></param>

''' <param name="e"></param>

''' <remarks></remarks>

Private Sub txtLocation_KeyPress(ByVal sender As System.Object, _

ByVal e As

System.Windows.Forms.KeyPressEventArgs) _

Handles txtLocation.KeyPress

dirtyForm = True

End Sub

''' <summary>

''' Dirty the form whenever the user

''' types into the bird name textbox

''' </summary>

''' <param name="sender"></param>

''' <param name="e"></param>

''' <remarks></remarks>

Private Sub txtBehavior_KeyPress(ByVal sender As System.Object, _

ByVal e As

System.Windows.Forms.KeyPressEventArgs) _

Handles txtBehavior.KeyPress

dirtyForm = True

End Sub

''' <summary>

''' Dirty the form if the user

''' opens the dtp control

''' </summary>

''' <param name="sender"></param>

''' <param name="e"></param>

''' <remarks></remarks>

Private Sub dtpDate_CloseUp(ByVal sender As System.Object, _

ByVal e As System.EventArgs) _

Handles dtpDate.CloseUp

dirtyForm = True

End Sub

''' <summary>

''' Dirty the form if the user

''' opens the dtp control

''' </summary>

''' <param name="sender"></param>

''' <param name="e"></param>

''' <remarks></remarks>

Private Sub dtpTime_CloseUp(ByVal sender As System.Object, _

ByVal e As System.EventArgs) _

Handles dtpTime.CloseUp

dirtyForm = True

End Sub

#End Region

End Class

That wraps up the discussion of the code contained in the main form of the application.

Code: List All Birds Form (Form2.vb)

The form used to display the entire list of birds contained in the current bird data list is pretty simple. The form contains a single data grid view control which is used to display the bird data list. The constructor was modified to accept a bird data list as an argument; the constructor binds the data grid view control to the bird data list and hides the first column (containing a Guid used to uniquely identify the record).

The code for this class is provided in total:

Imports System

Imports System.Collections.Generic

Imports System.ComponentModel

Imports System.Data

Imports System.Drawing

Imports System.Linq

Imports System.Text

Imports System.Windows.Forms

Public Class Form2

Public Sub New(ByVal bd As List(Of BirdData))

InitializeComponent()

' set the datasource of the grid

dataGridView1.DataSource = bd

' this is a guid to hide it

dataGridView1.Columns(0).Visible = False

End Sub

End Class

That concludes the description of the 'Form2' class.

Code: Find Birds Form (Form3.vb)

This form is used to provide the user with a list of the names of all of the birds contained in the current bird data list. The user can view and select bird names from the list and then click on the form's Find button; this will raise an event which will be used by the main form to load the matching bird into the form.

The class begins with the normal and default library imports, namespace declaration, and class declaration:

Imports System

Imports System.Collections.Generic

Imports System.ComponentModel

Imports System.Data

Imports System.Drawing

Imports System.Linq

Imports System.Text

Imports System.Windows.Forms

''' <summary>

''' This form class displays a list of existing

''' bird names for the user to pick from; once

''' selected, an event will be raised with

''' the selected bird name passed as an

''' argument. The main form will listen

''' for an process this event to update

''' the display of the current bird to match

''' the search bird.

''' </summary>

Public Class Form3

Following the class declaration, a delegate and event are declared; these are used to notify the main form whenever the user selects a bird from the form's list and then clicks the form's Find button. The 'BirdNameUpdateEventArgs' is declared as a separate class; that class will be used to contain the selected bird name and to make that information available to the main form whenever the event is raised.

' add a delegate

Public Delegate Sub BirdNameUpdateHandler(ByVal sender As Object, ByVal e As

BirdNameUpdateEventArgs)

' and associated event to notify

' listeners when a bird name is

' picked from this form's bird

' name list

Public Event BirdNameUpdated As BirdNameUpdateHandler

The constructor was modified to accept a bird data list as an argument; whenever an instance of the form is created, the constructor will iterate through the bird data list and add each bird name to the list box control used to display the bird names.

''' <summary>

''' Pass current bird data list to the

''' constructor so that the form can

''' generate a list of bird names for

''' the user to choose from

''' </summary>

''' <param name="bd"></param>

''' <remarks></remarks>

Public Sub New(ByVal bd As List(Of BirdData))

InitializeComponent()

' iterate the bird data to add

' each bird name to the bird

' name list box control

For Each bird As BirdData In bd

listBox1.Items.Add(bird.BirdName)

End Sub

The find button click event handler creates an instance of the event arguments and adds the list box control's selected item to the event arguments. Once set, the event is raised and raising the event will force the main form to load the selected bird's information into the form's controls.

''' <summary>

''' When the user clicks on the find button,

''' raise an event so the main form will display

''' the appropriate bird

''' </summary>

''' <param name="sender"></param>

''' <param name="e"></param>

''' <remarks></remarks>

Private Sub btnFind_Click(ByVal sender As System.Object, _

ByVal e As System.EventArgs) _

Handles btnFind.Click

' populate the argument list with the bird name

Dim args As New BirdNameUpdateEventArgs(listBox1.SelectedItem.ToString())

' raise the event to pass the bird name back to the

' main form for processing

RaiseEvent BirdNameUpdated(Me, args)

End Sub

The 'BirdNameUpdateEventArgs' class is used to contain the bird name and to facilitate passing the bird name to the main form whenever the bird name updated event is fired. This class could be expanded to contain greater numbers of properties.

''' <summary>

''' Container for the bird name update event arguments;

''' in this case there is only one argument, that being

''' the selected name of a bird from the bird list

''' </summary>

Public Class BirdNameUpdateEventArgs

Inherits System.EventArgs

Private mBirdName As String

' Class constructor

Public Sub New(ByVal sBirdName As String)

Me.mBirdName = sBirdName

End Sub

' Properties - Accessible by the listener

Public Property BirdName() As String

Get

Return mBirdName

End Get

Set(ByVal value As String)

mBirdName = value

End Set

End Property

End Class

That wraps up the discussion of the find form class (Form3.vb).

Summary

The article shows one approach that may be used to persist and manage data within a win forms application without actually backing the application with a database. Such an approach might be useful in a number of different applications and where the user does not share information with other users. Even though the example shows the approach used to manage a collection of information regarding birds, it could be used for any number of other purposes such as maintaining a library of fly patterns, or your favorite insect collection, inventories of tools or equipment, etc.