Web Forms :: Event Handlers For Dynamically Built Controls?
Mar 22, 2010
reading on the forums about assigning event handlers to controls that are dynamically created via code and am just not getting anywhere.In my particular case, I'm rolling through a directory of images and creating ImageButton controls on the fly and want to assign the OnCommand event to a single handler.Then, by using the CommandName (which is different for each control) I can figure out which ImageButton was clicked and act accordingly.
The snippet below (which can be found in many posts on this topic) is inside a foreach which loops through the directory and gets each FileInfo (fi).Each is then added to a PlaceHolder (phImages).
[Code]...
This code compiles and runs but the event handler is never invoked when an ImageButton is clicked. I believe this is because you cannot, without some coding I'm not familiar enough to do yet, assign a handler to multiple controls.I say this because I ran into a similar problem in a Silverlight app I wrote and had to use a lambda (=>) operator to do something similar (although I admit to not knowing enough about this to know if this situation is the same).
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Jul 15, 2010
I have a situation where I dynamically load one of twenty user controls at a time in an ASP.net web page. Based on much reading I've done, I understand that I am to reload the user control upon postback via the Page_Init event handler. This I've done and it seems to work fine.
But now I would like to wire up assorted controls in the user controls such that when the value of each is changed, an event is fired and the web page is notified. Here's an example of how I'm doing that:
userControl.NewData_Handler += new EventHandler(UserControl_NewData_Handler);
There's a problem though. Because the user control is being done in Page_Init (ie. before Page_Load) I don't believe that a line of code such as the one above can function yet.
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Nov 24, 2010
The textbox has an onblur event (the workings of the onblur event are irrelevant), and an associated RequiredFieldValidator. This code functions exactly as it should. However,if in the body onload event I simply raise an alert of the innerHTML of tr1 or td1, the onblur event does not appear (but it does work, and can be seen when I view source in IE7). If I remove the RequiredFieldValidator, the onblur event handler is shown in the alert, or if I retain the validator but change onblur to onfocus, then the event handler also appears in the alert. I need this to work as when the user increases the Quantity, duplicates of the table row are added (I have tried both cloneNode, and setting the innerHTML of each new table cell to that of the original, but as my alert proves, the onblur event handler is not included in what is copied). The same problem also occurs with onchange for select tags with validators. I am using Visual Studio 2008 (.Net
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[Code]....
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Dec 13, 2010
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Simply putting the code in the page load would produce an error.
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[Code]....
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Sep 7, 2010
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[Code]....
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[code].....
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Nov 3, 2010
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Sep 14, 2010
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Oct 28, 2010
I have the following on my aspx page
[Code]....
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[Code]....
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Nov 18, 2010
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Nov 9, 2010
let me know "Is there any method to check whether a control was attached with any Event Handlers or not"?
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Nov 1, 2010
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Feb 18, 2011
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[code]
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Feb 27, 2010
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[Code]....
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Feb 17, 2010
I have a Placeholder control on Employee Main Menu. Several SQL Data sources are run at page load in order to notify employees that something is due. Each "something is due" message is loaded into a unique label. Therefore the Placeholder could have several labels in them. For clarity's sake I'd like them separated by line breaks. However I understand from reading a previous forum item that "< /br>" are ignored. How can I embed a line break when PlaceHolder_Msg.Controls.Count > 1
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Mar 7, 2011
I have the following code, i add code for required validator, but when you make selection from dropdown to create the table, the page generates an error. Should the logic be somewhere else to add it to the table? i mean, dont they have to be there so when you submit the form, it fires the validation?
[Code]....
Here is the error that comes up, when i make a selection from my dropdown that creates the table.
Line: 938
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Feb 15, 2011
Can anyone clarify to me the difference between the following:
1.
{
// ...
Button b = new Button();
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}
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2.
{
// ...
Button b = new Button();
b.Click += a_Click;
}
void a_Click(object sender, RoutedEventArgs e) { //do stuff...... }
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Mar 26, 2010
I'm curious about the pros and cons when subscribing to event handlers.
<asp:DropDownList id="DropDownList1" runat="server" OnSelectedIndexChanged="DropDownList1_SelectedIndexChanged" />
vs
protected void Page_Init(object sender, EventArgs e)[code]...
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Apr 27, 2010
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Jul 8, 2010
VS 2008 - create event handlers in C#? but i cant get this:
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Apr 1, 2010
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ln.Click += new EventHandler(LinkClick);
....
public void LinkClick(object sender, EventArgs e)
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Jan 10, 2010
I want to add event handlers programmatically to the server controls rather than using their predefined OnClick properties, etc. But which would be considered a better practice for defining handlers:
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Apr 5, 2010
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Mar 17, 2010
I'm having a hard time understanding why the following code doesn't work. I'm sure it's something remedial that I'm missing or not understanding. I currently have a page that asks for user input. If, based on the input and logged in user, I find data from this page already in the database, I need to update the existing records rather than creating new ones, so I set a class-level bool to true. The problem is, when MyNextButton is clicked, PreviouslySubmitted is still false. So, I'm not sure how to make the value of this variable persist.
public partial class MyForm : System.Web.UI.Page
{
private bool PreviouslySubmitted;
protected void Page_Load(object sender, EventArgs e)
{
MyButton.Click +=
(o, i) =>
{
q = from a in db.TableA
where (a.SomeField == SomeValue)
select a;
if(q.Any())
{
PreviouslySubmitted = true;
//populate the form's fields with values from database for user to revise
}
}
MyNextButton.Click +=
(o, i) =>
{
//the value of PreviouslySubmitted is false at this point,
//even if I made sure it was set to true the previous postback
if(PreviouslySubmitted)
{
//update database
}
else
{
//insert into database
}
}
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