Such a simple question but if I want to add run some code in the OnPreRenderComplete Event for a Asp.Net page that inherits from a Master Page using Visual Studio Web Developer Express 2010 how can I do it?
Right clicking on the aspx page to get to properties allows me to select all the web controls in the drop down. Once I select one I can just click on the events tab and click in the event I want to have the empty method added to the .cs and register it for the event. But I don't see an option for Page.
What am I missing?
Not sure whether this feature is available in Web Developer Express but in Visual Studio you can add/select page event handler via:
Right mouse click on .aspx in solution explorer
Open "View Component Designer"
From properties windows - select "event" icon (yellow colored icon)
Double click on event name or type handler name by hand.
If AutoEventWireup page is set to "true" then the aspx page also automatically runs methods (special naming convention of page events) when certain events are raised. These names are Page_Init, Page_Load etc.
MSDN LINK : How to: Create Event Handlers in ASP.NET Web Pages
OnPreRenderComplete is a virtual method in the Page class that can be overridden with the override keyword.
protected override void OnPreRenderComplete(EventArgs e) {
// your code...
base.OnPreRenderComplete(e);
};
Don't forget, like I did, to call the base classes implementation...
actually I just remembered that I asked this very same question a while ago
and someone showed me this rather obscure way of doing it:
open the page in design view
right click on the background of the page
select view component designer
on the properties page you can now select the lightning bolt
double click an event name to generate the code
Related
I recently found that dropdownlist events are not shown in properties window.
I was disappointed.
I already hate asp.net designer in visual studio. its slow and full with ugly things like this.
please help me. I need to generate events automatically not to write it by hand.
It seems that the Properties Dropdown changes after viewing 'Split' or 'Design' view of the .aspx file at least once. In my case, I always left it in 'Source' mode and never saw the asp.net properties (and events) in Properties Dropdown.
The Design/Split/Soruce buttons are in the lower left of the text editor window pane.
I haven't found a good answer for this anywhere on the web so here it is:
After playing around I noticed that the Events options in Properties disappears after you have started editing the file. If you save or Ctrl+s then Visual Studio will reevaluate the page and realize its an actual ASP tag and give you the full properties with the events choices again.
You do not have to use Designer.
The solution is very easy.
It is just simple,it just that you can not see the events in the source view, you have to just switch to the design view to see the events and double click them to generate events.
and again come to design view
If you want to create OnSelectedIndexChanged Event you can double click your DropDownList in design view.
if not try writing this :
myDropDownList.SelectedIndexChanged +=
and then press tab 2 times. so it will create event handler for you. then you need to copy your handler name and paste it in your control markup.
I have found this too, only it happens on every control.
I found that if you are using "Source View", the events button is not shown in the properties window, but if you use design view and single click the control in design view (or "Both" view) then the events button is then shown in the properties window.
I suspect this is a bug in VS10? It's quite annoying as I don't like the Design view in VS, I always prefer Source view.
Can't speak for earlier versions of VS, but for 2013, after adding the element, Build the project. Sometimes I have to switch to Design view and back to Source view once on the page, but then the events appear:
Click the lightning bolt icon for the events.
Double click SelectedIndexChanged and it creates this in the codebehind:
protected void ddlChoice_SelectedIndexChanged(object sender, EventArgs e) {
}
And adds the event handler to the markup:
<asp:DropDownList runat="server" ID="ddlChoice" OnSelectedIndexChanged="ddlChoice_SelectedIndexChanged" />
When using VS2012 this can be done without actually going into Design view. I know the question is specifically for VS2010, but I can't test this answer myself.
In source view simply start adding the appropriate attribute, for example OnServerValidate on a CustomValidator. As soon as you type the = sign the very first item in the list is <Create new event>, which has the same function as double clicking the control.
At the top of your code page there are two comboboxes. Choose your dropdownlist from the one on the left (It says "(General)" by default) and then choose your event from the one on the right one.
It will create the event for you and so you can just add your code.
Click on the 'Split' view in MS Visual Studio - select a button in the 'Design' view and then look into property window now. You should be able to see Events now. Good luck.
ASP.NET 4.0 Webform website
master page:
left side panel (navigation menu purpose): use UpdatePanel control (AJAX), so when selecting new menu, the whole page won't reload. Only content part will be updated.
My question is -- I want to be able to use browser back button to go back to previous menu (with form state saved). However, when looking into the viewstate, it's always the same. Is there any way to do this? Thanks.
I guess one work around would be, when a user selects a menu item from the menu, put that selection in a session variable and in the page load. Then when the user hits the browser back button, you can set the menu in the page load, since you have values in your session variable.
What pst is referring to is "cross-page posting".
On your source page, you will need to set the asp button's postbackurl to your target page url.
In the target page c# onload method, set page.previouspage to your source page. Check if the previouspage's post was a crosspagepost.
If true, get zource page's viewstate.
How do you get access to the source page's viewstate from the target page? Save the source page's viewstate in the source page before going to the target page. Save the viewstate in an asp hidden variable on the source page, then get it in the target page using previouspage.findcontrol("variable name").
After getting the source page's viewstate, save it in an asp hidden variable on the target page.
When you want to return to the source page, you will do everything above in reverse, in a way.
The "back to previous page" link button will use the source page url for the postbackurl value.
In the source page's onload c# method, set the page.previouspage url to the target page's url. Check if the previouspage's post was a cross-page post.
If true, in the source page (after returning from target page) use previouspage.findcontrol("savedSourcePageViewstate") to get the saved viewstate of the source page.
I am not exactly sure yet how to then change the source page's viewstate to the saved viewstate. you might actually have to do it in the target page's backttopreviouspage button's click handler.
I am working at developing this process right now in a project i'm developing at work.
When i get it working, i'll create a full walkthrough for this, with code examples, and post the link to the walkthrough here.
However, i already haveworking the cross-page posting process of getting data from the source page in the target page.
It is secure, and is the best method that i have come across for getting data from one page to anotherin an asp.net webforms application.
When writing up a codebehind in Visual Studio for ASP.NET web forms applications, I often use the dropdowns at the top of the window to autogenerate page event handlers (e.g. Page_Load, Page_PreRender). I've noticed that sometimes Visual Studio likes to add numbers to these function names like "Page_Load1" or "Page_PreRender2".
Programatically speaking, this has no effect on the code. But stylistically, I find it a bit ugly. Is there any way to get rid of this behavior?
VS will do this if the event handler already exists, but has been disconnected from the event.
You can reproduce this behavior as follows.
Create a form with only a button (leave the default name of Button1
Double-click it to create the event handler Button1_Click
What you may not realize is that in addition to the code-behind, there is also a file for the designer and the .resx. I'm not sure which one has what, and I am not at a PC with Visual Studio, but in one of those files, there is a bunch of code defining the button, including a line that starts with
Button1.Click += new EventHandler
or something along those lines.
At this point all is good.. NOW to disconnect the button from the event...
In the form designer, delete the button
At this point, the Button1_click event handler still exists in code behind but is not tied to an event (because the button whose event it was tied to has been deleted.)
Drag a new button onto the form (still named Button_1)
At this point, there is a new Button_1, but the event handler is still not tied to your original Button1_Click event. So if you double-click on the button, a new eventhandler will be created (Button1_Click1())
I assume it would be happening because you've already got a method named Page_Load in the current scope: Visual Studio has to differentiate between your existing method and the new one somehow.
Note that if you remove an event handler, Visual Studio only deletes the method in the code-behind file if it's empty: if you've modified the code, then it won't delete it from the code-behind file.
When you edit a simple page in the design view, you can add an event on most components by simply double-clicking the relevant event. This does the binding and generates the function declaration in the codebehind for you.
In larger projects where the pages are complex, the design view can be extremely slow. Is there a way to quickly generate the codebehind stubs directly from the .aspx source?
Just begin typing the code to create your component.
For example, this is the code to add a button to your .aspx file:
<asp:Button ID="ButtonAction" class="btn panel-black" runat="server" Text="" OnClick="Function_Name_Here" />
When you get to typing the function name for the OnClick method...
for example, this part of the code:
OnClick="Function_Name_Here"
... Visual Studio will display a little pop-up window with the option to "<create new event>".
Select this option and the codebehind event handler stub will be generated for you.
In the markup view the Properties window is still available: you may have it hidden.
When it's shown and the cursor is in the markup for a particular control, you get that control's properties and events like you would in Design view. Similarly, in the event tab you can double-click the event (i.e Click) to automatically generate an empty declaration in code and hook up the event without ever having to go into the Design view.
I've been able to do this with ReSharper, but I've been using it for so long that I don't recall whether Visual Studio has this capability natively.
So i've got a custom user control. I have an event (SelectionChanged) and I'm wanting to have who ever uses my control to do the following to hook up the event:
drag the control to the page
in designer mode, click on the control
view the controls event handlers (from the properties window)
find the SelectionChanged event
double click and let visual studio create the code behind function and the wire-up on the aspx page.
How do i get this done? I've got the control setup so that the user can manually type in the event wire-up and code behind event by hand, but i want Visual Studio to do this.
Currently, when the a developer has dropped my control on the page, they can click on it and see the properties but no events are available (the lightning bolt isn't even there).
My events are public. Here they are:
public delegate void SelectionChangedDelegate(object sender, SelectionChangedEventArgs e);
public event SelectionChangedDelegate SelectionChangedEvent;
I don't understand how the lightning bolt isn't there. Is your control inheriting from System.Web.UI.HtmlControls.HtmlControl or System.Web.UI.Control or another derive control?
If you are inheriting from one of these controls, you should see the inherited events in the properties window.
The fact the lightning bolt isn't there leads me to believe that you aren't inheriting from one of the the control classes.
EDIT:
Well, you're not going to like this. UserControl doesn't behave the same as a WebControl. And as such, the VS Editor doesn't wireup the events.
If the Event Wireup is critcal for you (If this is going to be a sold library) I would recommend that you rewrite the control as a WebControl. This will require you to add all the controls programatically in the CreateChildControls override method.
You might also be able to wrap your UserControl inside of a WebControl and bubble up all the events that way.
Best of luck!