Passing variable from code behind to HTML tag in ASP.NET

Some how in some case, we want to directly passing variable that we already declare in ASP.NET with code behind to the HTML tag, like <input type = “TEXT”> tag in HTML, we can do that just with the simple code, here is the way:

Declare test as a property (at the class level) instead of a local variable, then refer to it as you currently do in your markup (aspx).

VB.NET 10 (automatic properties):

Protected Property test As String = "Test" 

---------------------------------------------

Pre-VB.NET 10 (no support for automatic properties)

Private _test As String
Protected Property Test As String
Get
     Return _test
End Get
Set(value As String)
     _test = value
End Set
End Property

——————————————————–

place that variable in HTML tag that you want to place, such as :

<input type=”TEXT” name=”SomeThing” size=”50″ maxlength=”250″ value = “<%= test %>”>

 

that’s all, hope this helpful

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XML Web Services

In this section we will build a more interesting Web service that returns a ADO .NET DataSet, containing the full set of records from a table. We will create our own database table and access the data from the table with this Web service. To Start, open Microsoft Access and create a new Database named Currency. Create a new table Table1 and add three columns named, Country Code, Country Name and Currency. Enter some values in the table and close it. Open Visual Studio .NET and select ASP .NET Web service from the projects type template. Drag a OleDb connection from the Data tab in the toolbox and using the properties window build a connection string that connects to the Currency database which we created. Switch to the code view and start writing the following code.

Imports System
Imports System.Web.Services
Imports System.Data.OleDb
‘import this namespace as we are working with an OleDb source<WebService(Namespace := “http://tempuri.org/&#8221;)>

_Public Class Service1 Inherits System.Web.Services.WebService

#Region ” Web Services Designer Generated Code ”

#End Region

<WebMethod()> Public Function GetData() As DataSet
‘WebMethod name is GetData,generate data set
Dim da as OleDbDataAdapter=new OleDbDataAdapter(“Select * From Table1”,_
OleDbConnection1)
‘dataadapter
Dim ds As DataSet=new DataSet()
‘declaring a new DataSet
da.Fill(ds, “Table1”)
‘filling dataadapter
Return ds
‘returning dataset
End Function
End Class

Consuming the Service

Once you finish with coding the Web service we need to consume this service. To do that, open a new Windows Application and from the toolbox drag a DataGrid and a Button. Our intention here is to load the data from Table1 in the Currency database into the DataGrid when we click the Button. Now, add a Web reference to the Web service by selecting Reference->Add WebReference in the Solution Explorer Window. Enter the URL of the service in the address bar and click “Add Reference“. That adds a reference to the Web Service. Now double-click on the Button and write the following code.

Public Class Form1Inherits System.Windows.Forms.Form

#Region ” Windows Form Designer generated code ”

#End Region

Private Sub Button1_Click(ByVal sender As System.Object, ByVal e_
As System.EventArgs)Handles Button1.Click
Dim myService As New localhost.Service1()
‘an instance of the Web service
Dim ds1 As DataSet = myService.GetData
DataGrid1.DataSource = ds1.Tables(“Table1”)
‘filling the datagrid with table
End Sub
End Class

Once you finish with the code, run the Windows Application and click on the Button. The data you entered in Table1 of the Currency database will be displayed in the datagrid. The difference, we are accessing the data with a Web service. The image below displays that.

Creating a Web service with VB.NET

Web services technology is based on HTTP, Simple Object Access Protocol (SOAP), and XML. Since Web services use open standards, calling Web services is fairly simple.

VB.NET allows you to use Web services as if they were entirely local objects since most of the marshaling between the client and the server is taking place in the background. This tip shows you how to create a simple Web service.

Example

I will create a Web service and add a Web function that will return the current machine’s IP address. Here are the steps for creating a Web service:

  1. Open Visual Studio.Net and select Create New Website under VB.NET.
  2. Select Web Service from the options listed.
  3. Once you get the code window open, add the following code:
<WebMethod()> _
        Public Function GetMachineIPAddress() As String         

         Dim strHostName As String = ""
         Dim strIPAddress As String = ""
         Dim host As System.Net.IPHostEntry         

         strHostName = System.Net.Dns.GetHostName()
         strIPAddress = System.Net.Dns.GetHostEntry(strHostName).HostName.ToString()         

         host = System.Net.Dns.GetHostEntry(strHostName)
         Dim ip As System.Net.IPAddress
         For Each ip In host.AddressList
             Return ip.ToString()
         Next         

         Return ""         

     End Function

Once you debug the example, you will see a screen that looks like Figure A.

Figure A

Figure A

It will list two available Web methods: the one that was generated (HelloWorld) and the one I created (GetMachineIPAddress). Click the link for GetMachineIPAddress, and you will see a screen allowing you to get more information about this method and invoking it (Figure B).

Figure B

Figure B

Click the Invoke button, and the result will look like Figure C.
Figure C

Figure C