This a just a basic webform setup of a listbox being populated with data from a database, in this case the Northwind Access database, and then populating textboxes with data related to the item the user selects.
1. WebForm
-Create an ASP.NET webform page
-Add a
listbox server control and set
AutoPostBack property to
True
-Add
9 textbox server controls and give them appropriate
ID's to match the
FieldNames from the datasource.
i.e txtProductID for ProductID, txtProductName for ProductName, etc
-Add a
checkbox server control for the
discontinued option for a particular product.
-For visual design purposes I would recommended associated labels to indicate what will appear in the textboxes.
Sample Code: -
Partial Code listing
<form id="Form1" method="post" runat="server">
<!-- ||||| BEGIN OUTER TABLE ||||| -->
<table id="tblMain" style="WIDTH: 568px; HEIGHT: 340px" cellSpacing="1" cellPadding="1" width="568" border="0">
<tr>
<td align="center" colSpan="2">Products</td></tr>
<tr>
<td style="WIDTH: 219px" rowSpan="9">
<asp:listbox id=lstProducts runat="server" autopostback="True" width="232px" height="299px"></asp:listbox>
</td>
<td style="HEIGHT: 199px"><!--- ||||| Start Inner Table ||||| -->
<table id="tblInner" cellSpacing="1" cellPadding="1" width="300" border="1">
<tr>
<td style=
"HEIGHT: 26px"><asp:label id=
"lblID" runat=
"server" Width=
"112px">Product ID</asp:label><asp:textbox id=txtID tabIndex=
"1" runat=
"server" width=
"48px" font-bold=
"True" enabled=
"False"></asp:textbox></td>
</tr>
<tr>
<td><asp:label id=
"lblProductName" runat=
"server" Width=
"112px">Product Name</asp:label><asp:textbox id=
"txtName" tabIndex=
"2" runat=
"server" ></asp:textbox></td>
</tr>
<tr>
<td><asp:label id=
"lblSupplier" runat=
"server" Width=
"112px">Supplier</asp:label><asp:textbox id=
"txtSupplier" tabIndex=
"3" runat=
"server" ></asp:textbox></td>
</tr>
<tr>
<td><asp:label id=
"lblCategory" runat=
"server" Width=
"112px">Category</asp:label><asp:textbox id=
"txtCategory" tabIndex=
"4" runat=
"server" ></asp:textbox></td>
</tr>
<tr>
<td><asp:label id=
"lblQtyPerUnit" runat=
"server" Width=
"112px">Quantity Per Unit</asp:label><asp:textbox id=
"txtQtyPerUnit" tabIndex=
"5" runat=
"server" ></asp:textbox></td>
</tr>
<tr>
<td><asp:label id=
"lblUnitPrice" runat=
"server" Width=
"112px">Unit Price</asp:label><asp:textbox id=
"txtUnitPrice" tabIndex=
"6" runat=
"server" ></asp:textbox></td>
</tr>
<tr>
<td><asp:label id=
"lblUnitsInStock" runat=
"server" Width=
"112px">Units
In Stock</asp:label><asp:textbox id=
"txtUnitsInStock" tabIndex=
"7" runat=
"server" ></asp:textbox></td>
</tr>
<tr>
<td><asp:label id=
"lblUnitsOnOrder" runat=
"server" Width=
"112px">Units on Order</asp:label><asp:textbox id=
"txtUnitsOnOrder" tabIndex=
"8" runat=
"server" ></asp:textbox></td>
</tr>
<tr>
<td><asp:label id=
"lblReorderLevel" runat=
"server" width=
"112px">Reorder Point</asp:label><asp:textbox id=
"txtReOrder" tabIndex=
"9" runat=
"server" ></asp:textbox></td>
</tr>
<tr>
<td><asp:Label id="lblDC" runat="server" Width="112px">Discontinued</asp:Label>
<asp:checkbox id="chkDC" tabIndex="10" runat="server"/></td>
</tr>
</table><!-- ||||| END OF INNER TABLE ||||| --->
</td>
</tr>
</table><!-- ||||| END OUTER TABLE ||||| -->
<p><asp:label id=lblMsg runat="server" width="568px"></asp:label></p>
</form>
2. Web.Config Settings - Connection String
-Modify to meets your particular setup.
-I prefere to place the connection string in the web.config file
as it does add a performance boost, as well as simplify coding a web application that consistantly uses the same DataSource.
-CASE SENSITIVE!
Sample Code: -
Partial Code listing
<configuration>
<!-- ||||| Application Settings ||||| -->
<appSettings>
<add key="strConn" value="Provider = Microsoft.Jet.OLEDB.4.0;Data Source=C:\Inetpub\wwwroot\Northwind.mdb;User ID=Admin;Password=;" />
</appSettings>
<system.web>
' ...
' ...
' ...
3. Write the code behind for the WebForm
a. Import Required Namespaces
Imports System.Web.Security ' ||||| Required Class for Authentication
Imports System.Data ' ||||| DB Accessing Import
Imports System.Data.OleDb ' |||||| Access Database Required Import!
Imports System.Configuration ' |||||| Required for Web.Config appSettings |||||
b. Create Class Variable(s)
Dim MyConn As OleDbConnection = New OleDbConnection(ConfigurationSettings.AppSettings("strConn"))
c. Add the code in the Page_Load Event to populate the listbox
Private Sub Page_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
If Not Page.IsPostBack Then
' ||||| Fill the Listbox with Product Items
ListLoad()
' ||||| Set the default selected item (usually the first on the list)
lstProducts.SelectedIndex = 0
End If
End Sub
ListLoad() Subroutine
' ||||| FILL THE LIST BOX |||||
Private Sub ListLoad()
' ||||| DECLARE VARIABLES |||||
Dim strProducts As String = "SELECT ProductID, ProductName FROM Products"
Dim oCmd As New OleDbCommand(strProducts, MyConn)
Dim objReader As OleDbDataReader
Try
' ||||| Check if Connection to DB is already open, if not, then open a connection
If MyConn.State = ConnectionState.Closed Then
' ||||| DB not already Open...so open it
MyConn.Open()
End If
' ||||| Set DataReader Obj to Results of the connection made
' ||||| Setting the DataReader this way will allow you to close the reader
' ||||| and the connection as the same time.
objReader = oCmd.ExecuteReader(CommandBehavior.CloseConnection)
' ||||| Clear any possible items in the Listbox prior to databinding.
lstProducts.Items.Clear()
' ||||| Set the DataValueField to the Primary Key
lstProducts.DataValueField = "ProductID"
' ||||| Set the DataTextField to the text/data you want to display
lstProducts.DataTextField = "ProductName"
' ||||| Set the DataSource the the OleDBDataReader's result
lstProducts.DataSource = objReader
' ||||| Bind the Source Data to the Web/Server Control
lstProducts.DataBind()
' ||||| Close the Connection and the Reader
objReader.Close()
Catch ex As Exception
' ||||| Handle any Exceptions
MsgBox("Error Connecting to Database!", MsgBoxStyle.Critical)
End Try
End Sub
-Now that you have the listbox populated, what about the textboxes?
-Well, what we want to happen is that when the user selects any item in the listbox we want to have the data on that item populate the textboxes.
-The first two steps have been done to make this work. The first was setting the
AutoPostBack property to
True for the listbox, and the second was
setting the
DataValueField (
primary key) and
DataTextField for the listbox data. The third part is now obtain the data on the selection the user has made, which is done by the code in the
SelectedIndexChanged event
SelectIndexChanged code :
rivate Sub lstProducts_SelectedIndexChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles lstProducts.SelectedIndexChanged
' ||||| "This event will post to the server only if the AutoPostBack property is TRUE ||||
' ||||| If the Index of the selected item is changed
' ||||| (default = 0, i.e. First item in list)
' ||||| Then display the details of the selected item
' ||||| DELCARE VARIABLES |||||
Dim objCmd As OleDbCommand
Dim objReader As OleDbDataReader
Dim strSQL As String
' ||||| Create SQL String
strSQL = "SELECT ProductID, ProductName, QuantityPerUnit, UnitPrice, UnitsInStock,"
strSQL &= " UnitsOnOrder, ReorderLevel, Discontinued FROM Products"
strSQL &= " WHERE ProductID = "
' ||||| Returns the DataValueField
strSQL &= lstProducts.SelectedItem.Value
objCmd = New OleDbCommand(strSQL, MyConn)
Try
If MyConn.State = ConnectionState.Closed Then
MyConn.Open()
End If
objReader = objCmd.ExecuteReader(CommandBehavior.CloseConnection)
' ||||| Loop through the Reader to retrieve data
' ||||| and set each textbox/checkbox to appropriate data from datasource
While objReader.Read()
With objReader
txtID.Text = .Item("ProductID")
txtName.Text = .Item("ProductName")
txtQtyPerUnit.Text = .Item("QuantityPerUnit")
txtUnitPrice.Text = .Item("UnitPrice")
txtUnitsInStock.Text = .Item("UnitsInStock")
txtUnitsOnOrder.Text = .Item("UnitsOnOrder")
txtReOrder.Text = .Item("ReorderLevel")
chkDC.Checked = .Item("Discontinued")
End With
End While
Catch ex As Exception
lblMsg.Text = ex.Message
End Try
'End If
End Sub
Now just "run" the webform and you are done.
Of course this is a simple set of code and concept, but the principles that you can now build on from here will enable you do a variety to things, like dropdown menu lists, or listboxes of background color choices, just to name a few.
I could have done a number of things different, or have add more funcitonality, which I do plan to do. As I modify and expand this concept further I will post the changes and the results.
Happy Coding!
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