Solved

ASP.NET event handler for a DropDown control

Posted on 2015-02-05
1
234 Views
Last Modified: 2015-02-06
I am new to ASP.NET. Normally, when working with Windows Forms, you have events that trigger methods. For example, if a user clicks on a button, the btnRun_OnClick event is called, and the code control jumps to the first line in that method.

However, it appears that with the ASP.NET code below, when the user changes the selected item in a drop down control, a PostBack happens.

Question: Am I correctly assuming that in Windows Forms, events always call methods (Event Handlers), and in ASP.NET, events always are handled via PostBack? What if for the below code, I want to run some code in method Foo(), how would I do that?

<tr>
		                            <td class="ControlLayoutCell" colspan="2">
		                                <cc1:I1Label runat="Server" ID="lblCCPaymentProcessor" Text="Credit Card Payment Processor:" CssClass="LabelGeneric" Width="100%" />
		                            </td>
		                            <td class="ControlLayoutCell">
		                                <cc1:I1DropDownList runat="server" ID="cboCCPaymentProcessor" Width="100%" TabIndex="90" AutoPostBack="true" OnSelectedItemChanged="cboCCPaymentProcessor_SelectedItemChanged"></cc1:I1DropDownList>
		                            </td>
		                        </tr>

Open in new window

0
Comment
Question by:pzozulka
[X]
Welcome to Experts Exchange

Add your voice to the tech community where 5M+ people just like you are talking about what matters.

  • Help others & share knowledge
  • Earn cash & points
  • Learn & ask questions
1 Comment
 
LVL 29

Accepted Solution

by:
Paul Jackson earned 500 total points
ID: 40592728
Yes that is correct events are fired when a postback occurs whether this is because an event has been triggered by a control such as a dropdown list item being changed or a button being clicked.

The postback is occurring because you have set the AutoPostBack property to true for the dropdown list it will then call the method specified in the OnSelectedItemChanged property which is currently set to cboCCPaymentProcessor_SelectedItemChanged if you want to call foo() when a user changes the selected item I would put the foo() method call in the cboCCPaymentProcessor_SelectedItemChanged event handler in the code behind.

If you don't want foo() to be called when the dropdown list item is changed and instead when a button is clicked then remove the AutoPostBack=True from the dropdown list and then add a button and add the foo() method call to the button click event handler. By default all button clicks will cause a postback.
0

Featured Post

Prepare for your VMware VCP6-DCV exam.

Josh Coen and Jason Langer have prepared the latest edition of VCP study guide. Both authors have been working in the IT field for more than a decade, and both hold VMware certifications. This 163-page guide covers all 10 of the exam blueprint sections.

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

More often than not, we developers are confronted with a need: a need to make some kind of magic happen via code. Whether it is for a client, for the boss, or for our own personal projects, the need must be satisfied. Most of the time, the Framework…
Real-time is more about the business, not the technology. In day-to-day life, to make real-time decisions like buying or investing, business needs the latest information(e.g. Gold Rate/Stock Rate). Unlike traditional days, you need not wait for a fe…
There are cases when e.g. an IT administrator wants to have full access and view into selected mailboxes on Exchange server, directly from his own email account in Outlook or Outlook Web Access. This proves useful when for example administrator want…
Monitoring a network: why having a policy is the best policy? Michael Kulchisky, MCSE, MCSA, MCP, VTSP, VSP, CCSP outlines the enormous benefits of having a policy-based approach when monitoring medium and large networks. Software utilized in this v…

626 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question