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<pre>
Title: Record Navigation in Web Forms using Events in c#
Author: M. Raja Rajeswari
Email: rajee_mr_rajee@hotmail.com
Environment: c#
Keywords: Event Handling, Record Navigation,View State
Level: Intermediate
Description: An article on something-or-other
Section Miscellaneous
SubSection General
</pre>
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<li>
<a href="C:\Documents and Settings\m.rajarajeswari\Desktop\WebForm.zip">Download
source - XXX Kb</a></li>
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width="1000" height="400"></p>
<!------------------------------- STEP 3 --------------------------->
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<h2>Introduction</h2>
<p>This article explains you how to do Record Navigation in Web Form using c#.
First have a look at my sample web form.
<h2>Using the code</h2>
<p>I have used Web User Control for the images to be used in all other web forms.
In the User Control Page I have declared the Event.<BR>
<pre>
Syntax:<br>
public delegate void InsertEventHandler(object sender, EventArgs e);
public event InsertEventHandler NewRecord;
</pre>
<p>
Now I will tell u how to raise the event in the Image Button Click of New.
</p>
<pre>
private void btnNewImage_Click(object sender, System.Web.UI.ImageClickEventArgs e)
{
OnNew(e);
}
</pre>
<p>
First u have to write a function to raise the event and then call the function
in the Image Button Click. In the function u can write like this.
</p>
<pre>
protected virtual void OnNew(EventArgs e)<br>
{
if(NewRecord!= null)<br>
{
NewRecord(this,e);<br>
}
}
</pre>
<p>
So far u have seen how to decalre an even and raise the event in the
UserControl Page. Now u want to use this event in the web form.
<br>
<br>
How do u do that?<br>
<br>
It is very simple. Let me explain.<br>
<br>
1. To use the Web UserControl in the Web Form just drag the UserControl to the
Web Form.<br>
2. Then give a name to the UserControl. For eg. GenericUserControl.<br>
3. In the InitalizeComponent() of the Web Form u have to initialize that event.<br>
Example is shown below.
<pre>
#region Web Form Designer generated code
override protected void OnInit(EventArgs e)
{
// CODEGEN: This call is required by the ASP.NET Web Form Designer.
InitializeComponent();
base.OnInit(e);
}
private void InitializeComponent()
{
this.GenericUserControl.NewRecord +=new SamWebApp.frmUserControl.InsertEventHandler(GenericUserControl_NewRecord);
this.Load += new System.EventHandler(this.Page_Load);
}
#endregion
</pre>
<p>
4. Then in the Web Form u have to write the function for
GenericUserControl_NewRecord.
<pre>
private void GenericUserControl_NewRecord(object sender, EventArgs e)
{
// ur code comes here...
// what u want to do in the button click event write here.
}
</pre>
</p>
<p>
Now coming to the Record Navigation, how to find the
<br>
<b>I . First Record in the Datatable?</b>
<br>
Follow the above steps mentioned:
<br>
1. Initialize an event for the FirstRecord.
<br>
2. Then write the function for that event.
<pre>
private void GenericUserControl_MoveFirstRecord(object sender,EventArgs e)
{
DataSet dsDataSet = new DataSet();
DataTable dtDataTable = new DataTable();
if(dsDataSet!=null)
{
dtDataTable = dsDataSet.Tables[0];
ViewState["currRow"] =0;
}
SetNavigationRecord();
}
private void SetNavigationRecord()
{
txtCustId.Text=dtDataTable.Rows[(int)ViewState["currRow"]]["CustomerID"].ToString();
txtCompName.Text=dtDataTable.Rows[(int)ViewState["currRow"]]["CompanyName"].ToString();
txtContName.Text=dtDataTable.Rows[(int)ViewState["currRow"]]["ContactName"].ToString();
txtContTitle.Text=dtDataTable.Rows[(int)ViewState["currRow"]]["ContactTitle"].ToString();
txtAddress.Text=dtDataTable.Rows[(int)ViewState["currRow"]]["Address"].ToString();
txtCity.Text=dtDataTable.Rows[(int)ViewState["currRow"]]["City"].ToString();
txtRegion.Text=dtDataTable.Rows[(int)ViewState["currRow"]]["Region"].ToString();
txtPostalCode.Text=dtDataTable.Rows[(int)ViewState["currRow"]]["PostalCode"].ToString();
txtCountry.Text=dtDataTable.Rows[(int)ViewState["currRow"]]["Country"].ToString();
txtPhone.Text=dtDataTable.Rows[(int)ViewState["currRow"]]["Phone"].ToString();
txtFax.Text=dtDataTable.Rows[(int)ViewState["currRow"]]["Fax"].ToString();
}
</pre>
<p>
What is ViewState and Why are we using viewstate?
<br>
<br>
ViewState gets the dictionary of state of information that allows u to save and
restore the viewstate of a server control across multiple requests for the same
page.
</p>
<p>
<b>II. Next Record in the DataTable</b>
<pre>
private void GenericUserControl_MoveNextRecord(object sender,EventArgs e)
{
if(dsDataSet!=null)
{
dtDataTable = dsDataSet.Tables[0];
totRow=dtDataTable.Rows.Count;
ViewState["currRow"] =((int)ViewState["currRow"]) + 1;
if ((int)ViewState["currRow"] >= totRow)
{
ViewState["currRow"] =0;
}
SetNavigationRecord();
}
}
</pre>
</p>
<p>
<b>III. Previous Record in the DataTable</b>
<pre>
private void GenericUserControl_MoveNextRecord(object sender,EventArgs e)
{
if(dsDataSet!=null)
{
dtDataTable = dsDataSet.Tables[0];
totRow=dtDataTable.Rows.Count;
ViewState["currRow"] =((int)ViewState["currRow"]) + 1;
if ((int)ViewState["currRow"] >= totRow)
{
ViewState["currRow"] =0;
}
SetNavigationRecord();
}
}
</pre>
</p>
<p>
<b>IV. Last Record in the DataTable</b>
<pre>
private void GenericUserControl_MoveLastRecord(object sender,EventArgs e)
{
if(dsDataSet!=null)
{
dtDataTable = dsDataSet.Tables[0];
totRow=dtDataTable.Rows.Count;
ViewState["currRow"] =totRow -1;
}
SetNavigationRecord();
}
</pre>
</p>
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