|
|
 |
|
|
|
|
Restoring an Active Tab |
|
Learn how to restore an active tab when navigating back to previous pages.
- Jing Ding, Senior Systems Consultant, Ohio State University Medical Center
January 25, 2010
Iron Speed Designer V6.X
|
|
Introduction |
|
Iron Speed Designer’s generated master-detail pages put child tables in a tab container.
If there are multiple tabs, the active tab is not “memorized” when navigating from page to
page. However, there may be times you want the active tab memorized across page navigation.
For example, if you click a row edit button on the second tab, you are redirected to an Edit
Record page. After you save the changes and go back to the previous page, the page shows the
first tab, but not the second tab. This article shows you how to restore the active tab across
page navigation.
|
Solution |
|
Since the active tab needs to be remembered across page navigation, it has to be stored in a session
variable. The best place to retrieve and restore the active tab from the session variable is the page’s
PreRender event handler. To store the active tab into the session variable you will have to add custom
code to multiple exit points on the page. For example, within a child table, there are three table buttons
(New, Edit, and Copy) and three row buttons (Edit, View, Copy). In their button click event handlers, at least
one line of custom code is needed to store the active tab. If there are three child tables, the same code will
be cut-and-pasted in 18 (3 x 6) places. That is a maintenance nightmare!
Fortunately, Iron Speed Designer already has a built-in single point of exit. Before redirecting to
other pages, all Iron Speed Designer pages call the SaveControlsToSession() function. Generated applications
use the function to store filters and search boxes of table controls. We can take advantage of this to store
active tabs.
|
Implementation |
|
In the page’s code-behind file (MyPage.aspx.cs or MyPage.aspx.vb), override SaveControlsToSession() and ClearContorlsFromSession() functions, and insert two lines of code in LoadData() function. That’s it.
C#:
protected override void SaveControlsToSession() {
base.SaveControlsToSession();
SaveToSession(MyTabContainer, MyTabContainer.ActiveTabIndex.ToString());
}
protected override void ClearControlsFromSession() {
base.ClearControlsFromSession();
RemoveFromSession(MyTabContainer);
}
public void LoadData() {
// LoadData reads database data and assigns it to UI controls.
// Customize by adding code before or after the call to LoadData_Base()
// or replace the call to LoadData_Base().
LoadData_Base();
if (InSession(MyTabContainer))
MyContainer.ActiveTabIndex = Convert.ToInt32(GetFromSession(MyTabContainer));
}
|
VB .NET:
Protected Overloads Overrides Sub SaveControlsToSession()
MyBase.SaveControlsToSession()
SaveToSession(MyTabContainer, MyTabContainer.ActiveTabIndex.ToString())
End Sub
Protected Overloads Overrides Sub ClearControlsFromSession()
MyBase.ClearControlsFromSession()
RemoveFromSession(MyTabContainer)
End Sub
Public Sub LoadData()
' LoadData reads database data and assigns it to UI controls.
' Customize by adding code before or after the call to LoadData_Base()
' or replace the call to LoadData_Base().
LoadData_Base()
If InSession(MyTabContainer) Then
MyTabContainer.ActiveTabIndex = Convert.ToInt32(GetFromSession(MyTabContainer))
End If
End Sub
|
Please note that the active tab is restored in the LoadData() function, instead of a PreRender
event handler. This is because Iron Speed Designer has its own PreRender event handler where
ClearControlsFromSession() is called. If you add your own PreRender handler, it is not guaranteed
to be called before Iron Speed Designer’s handler. If Iron Speed Designer’s handler is called first,
the active tab is cleared from the session, and you won’t be able to restore it. Therefore, the code
is moved into LoadData(), which is called before any PreRender handlers.
|
Conclusion |
|
Taking advantage of Iron Speed Designer’s built-in infrastructure to restore an active tab across page
navigation only requires a few lines of code in a central location.
|
About the Author |
|
Jing Ding has a PhD in Computer Engineering, Bioinformatics and Computational Biology, and an M.S. in Toxicology
from Iowa State University. He received his B.S. in biophysics from Fundan University in Shanghai, China. He is a
self-taught programmer who "played" with assembly, C and C++ in the 1990s. He took a break from programming from
1997 to 2000. When he picked it up again in 2001, he worked with Java. Jing began working with C# and .NET in 2006.
|
|
|
|
|
|
|
|
|
|
