How to access the controls of source page from the target Page?

ASP.Net 2.0 Page object now comes with a property called PreviousPage which gives the access to the posted page.

Page P=Page.PreviousPage;

The Page object comes with a method called FindControl() which takes the control ID as parameter and gives the access to that control.

TextBox text=(TextBox)P.FindControl(“txtDOB”);

Or

TextBox text=(TextBox)PreviousPage.FindControl(“txtDOB”);

The code for the source and target page will be,

SourcePage:

<asp:TextBox ID="txtDOB" runat="server"></asp:TextBox>

<asp:Button ID="btnGeturAge" runat="server" PostBackUrl="~/Target.aspx" Text="Calculate Age" />

TargetPage:

protected void Page_Load(object sender, EventArgs e)

{

Page P=Page.PreviousPage;

TextBox text=(TextBox)P.FindControl(“txtDOB”);

}

<%@ PreviousPageType %> Directive:

In the above example, to access a control that is declared in source page we have to redeclare it in the target page. ASP.Net 2.0 has a PreviousPageType directive to redeclare the source page in the target page. Also, we have to declare a public property for every control in source page to access it in the target page.

<%@ PreviousPageType VirtualPath="~/Default.aspx" %>

So the code will be like,

SourcePage:

<asp:TextBox ID="txtDOB" runat="server"></asp:TextBox>

<asp:Button ID="btnGeturAge" runat="server" PostBackUrl="~/Age.aspx" Text="Calculate Age" />

public DateTime DOB

{

get

{

return Convert.ToDateTime(txtDOB.Text);

}

}

TargetPage:

<%@ PreviousPageType VirtualPath="~/SourcePage.aspx” %>

protected void Page_Load(object sender, EventArgs e)

{

DateTime dt=PreviousPage.DOB;

}

When the source page is posted to the target page, the target page will get executed for the first time which makes target page’s IsPostback to be false.The source page will be loaded into the memory and executes all the events except the render event. To ensure that the page is executed for a cross page postback there is a property called IsCrossPagePostBack in PreviousPage object which will be true for a cross page postback.

PreviousPage.IsCrossPagePostBack

So we can write the above code like,

if (PreviousPage.IsCrossPagePostBack)

{

DateTime dt=PreviousPage.DOB;

}