.net - Attribue To Verify Field Is Initilized By A Given Point In .Net Page Lifecycle?
Jul 12, 2010
I would like to create an attribute I can decorate specific fields or properties with. This attribute will throw an exception if the field or property it decorates is null at a given point in an ASP.Net page lifecycle. I.E. if a property, "x", is null at the prerender stage of an ASP.Net page, it will cause a "ArgumentNullException" exception to be throw with a nice message. Or a mean message. Either way, a message of my choosing.
Is this possible with standard .Net attributes, or would some kind of Spring.Net magic be required?
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Jan 29, 2010
I have a user control embedded in a web part. It has the following snippets of code:
[code]....
Why are some controls initialised and others not? How do I get around this if I'd like to update the Text property on currentPageLabel?
Update:
I've placed breakpoints all the way through the page life cycle and found that nextButton and currentPageLabel are never initialised. The breakpoints were placed at OnLoad, CreateChildControls, goButton_Click, OnPreRender, Render and OnUnload.
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Dec 16, 2010
I'm using a file manager-type WebControl that does lots of postbacks. It's placed inside a Page that is relatively complex. I would like to prevent the WebControl from causing the whole Page to go through the lifecycle.
Is there any way to isolate the WebControl from the rest of the Page? The only way I can think of is sticking the WebControl in a separate Page and creating an iframe in the original Page. Unfortunately that also means my WebControl properties/settings are no longer in the original Page. If I want two instances of the WebControl with different settings, then I have to create a Page for each setting and reference the correct one in my iframes. Not quite as "drag & drop" as I would like.
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Sep 14, 2010
Does the OnActiveStepChanged method of an asp:Wizard control get processed after Page_Load and before Page_LoadComplete?
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Feb 9, 2011
I have a ListView in a web form (c#/.net 4.0). There is an ImageButton in the ItemTemplate.
After a postback, the ItemCommand event fires... and then everythings stops. No other page events occur. (Actually there is one other thing: Dispose() from ExtenderControlBase runs right after the event code finishes - this site has some AjaxControltoolkit controls, though there are none on this particular page).
There are a lot of things involved here so it's not really practical to post all the code, but generally, is there anything that could cause this?
I am rebinding the ListView on each postback, because I'm handling paging on the server side. When I assign the data source to the ListView, it's initially going to have no rows. So at the time the command event fires, the DataSource has no data in it, since it hasn't yet been loaded from the database and rebound. I can't think why this would cause the entire page to just stop loading, though.
The template is just this:
<ItemTemplate>
<tr>
<td class="DataListRow"><asp:ImageButton ID="edit" runat="server" ImageUrl="~/images/nav/datagrid_edit.gif" CommandName="edit" />
</td>
// a few orther cells
</tr>
</ItemTemplate>
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May 10, 2010
I'm working on an ASP.NET project in which the vast majority of the forms are generated dynamically at run time (form definitions are stored in a DB for customizability). Therefore, I have to dynamically create and add my controls to the Page every time OnLoad fires, regardless of IsPostBack. This has been working just fine and .NET takes care of managing ViewState for these controls.
protected override void OnLoad(EventArgs e)
{
base.OnLoad(e);
RenderDynamicControls()
}
private void RenderDynamicControls(){
//1. call service layer to retrieve form definition
//2. create and add controls to page container
}
I have a new requirement in which if a user clicks on a given button (this button is created at design time) the page should be re-rendered in a slightly different way. So in addition to the code that executes in OnLoad (i.e. RenderDynamicControls()), I have this code:
protected void MyButton_Click(object sender, EventArgs e)
{
RenderDynamicControlsALittleDifferently() [code]
My question is, is this really the only way to accomplish what I'm after? It seems beyond hacky to effectively render the form twice simply to respond to a button click. I gather from my research that this is simply how the page-lifecycle works in ASP.NET: Namely, that OnLoad must fire on every Postback before child events are invoked. Still, it's worthwhile to check with the SO community before having to drink the kool-aid.
On a related note, once I get this feature completed, I'm planning on throwing an UpdatePanel on the page to perform the page updates via Ajax.
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Feb 17, 2010
when does the constructor on a page in asp.net page lifecycle get called?
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Oct 22, 2010
I'm working with dynamic fields in ASP.NET due to a very specifc and rigid end-user requirement that would take 2 hours just to explain. Suffice it to say, I can't make the requirement go away.
Anyway, I have a working solution in place; no problems with controls loading, rendering or maintaining their ViewState. This is what my OnLoad looks like:
[code]....
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Nov 28, 2010
I'm creating a page that users can upload a file to the webserver. After upload the page will then have a link to the file that has just been uploaded, along with any other files that have already been uploaded.As I am programatcially creating links to the files which have been uploaded, I have to do this in page_init or else the link button won't fire off it's event when clicked. MY web page does all this - it creates the link buttons and when I click on them, it calls the event method required i.e. a sub to download the file.
OK, the problem I've come accross is: when I click upload (to upload the file) - the page_init sub is called, displaying all the previously uploaded files as link buttons. Then my btnUpload_click sub is called, which uploads my current file. The only prob is the current file hasn't been displayed? I can only display links in the page_init, but because btnUpload is called after the page_init, the current file isn't uploaded until after page_init and therefore not dislayed?
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Dec 13, 2010
Not point to the break point.it gives above error massege when start debbuging. How i fix this.
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Jan 27, 2010
I would like to wrap Session variables in a manner similar to that discussed on CodeProject.
[code]....
Here is my question: if I have to access CurrentUser multiple times in the same page, would I get a performance improvement by assigning it to a local variable instead of accessing the wrapping property? Or does the HttpSessionState make sure the object is only deserialized once per request, so that subsequent calls in the same http request don't cost any more?
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Nov 19, 2010
I need to capture the amount of time that ASP.net takes to execute each page request in my application, but I need to exclude any network latency. I am currently capturing render times by using the StopWatch class and starting the stopwatch during the OnInit method of the page lifecycle and stopping it after the Unload method completes. It seems that the Unload method includes the time it takes send the request to the client, thus including any internet/network latency. What is the last possible point I could stop the stopwatch in the Page Life Cycle that would not include the time it takes to send the request to the client. Would it be directly before the Unload event?
Related question: Does ASP.net finish building the response before it starts sending to the client? Or does it start sending asynchronously, while the response is being formed?
I am using ASP.Net 2.0 with IIS 5 currently.
I have this code in a class that all of my pages inherit from:
readonly Stopwatch _serverExecutionTime = new Stopwatch();
protected override void OnInit(EventArgs e)
{
_serverExecutionTime.Start();
base.OnInit(e);
}
protected override void OnUnload(EventArgs e)
{
_serverExecutionTime.Stop();
base.OnUnload(e);
}
UPDATE
I tried capturing the execution time at the end of the OnRender method, at the start of the OnUnload method and at the end of the OnUnload method. In all three cases the difference in times was at most 1 millisecond. Even when testing this from a client in Europe to a server in the USA, the times were identical.
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Jul 30, 2010
It seems that ASP.NET MVC just runs on top of ASP.NET WebForms. System.Web.Mvc.ViewPage in ASP.NET MVC inherits from System.Web.UI.Page which includes page lifecycle methods like OnRender and friends.
I have seen a couple of comments around the web to the effect that you should resist the urge to override these methods AT ALL COSTS!. Of course, this means that I find myself resisting the urge to do just that.Is there really that much wrong with something like the following?
public class SslPage : ViewPage
{
protected override void OnPreInit(EventArgs e)
{
// Make sure we are using SSL [code].....
One could debate the purity of putting that in a "View" but it seems plenty expedient.How dangerous/blasphemous is it to override these methods? When might it make sense?
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Jan 5, 2011
I have a page on which everything is loaded dynamically.
There is a Gridview (AutoGenerateColumns=true) and in the RowDataBound I check every column for a boolean datatype. If found I add a checkbox (autopostback=true) to the cell and register the CheckedChanged event.
The problem is, that I only get the CheckedChanged event, if I reload the grid in Page_Load:
protected void Page_Load(object sender, EventArgs e) {
LoadGrid();
}
But this is very expensive and causes that the db request will be executed twice. If I changed the code to what I want:
protected void Page_Load(object sender, EventArgs e) {
if (!this.IsPostBack)
loadGrid();
}
I get no CheckedChanged event.
Is there a possibility to get:
- Adding a Checkbox in RowDataBound
- Only "LoadGrid()" if it is no PostBack
- Getting the CheckedChanged event of the relevant row
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Aug 22, 2010
I have a previously working ASPX website which also supports AJAX. However, we just upgraded our SQL Server from 2008 Evaluation to 2008 R2 version 10.50.16 and now this website is no longer working. I believe the problem is that now we need to again restore original SQL accounts and settings prior to this upgrade. This website also uses AJAX. Which accounts need to be created to fix this problem? When I navigate to this URL, I get the message below:
The address is not valid.
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Aug 22, 2010
I have a previously working ASPX website which also supports AJAX. However, we just upgraded our SQL Server to a new version and now this website is no longer working. I believe the problem is that now we need to again restore original SQL accounts and settings prior to this upgrade. This website also uses AJAX. Which accounts need to be created to fix this problem? When I navigate to this URL, I get the message below:
The address is not valid.
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Aug 9, 2010
The normal order for creating a web site is to creating a master page, then add a new web form and point it to the master page. However, I created my web form first, then created the master page. I am using 2008 express.
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Feb 22, 2010
I'm trying to use an to point to an .aspx file, but when I load it I keep getting an empty frame, no matter what is in the target aspx nothing gets displayed. Here the html:
<html xmlns="http://www.w3.org/1999/xhtml" >
<head runat="server">
<title></title>
</head>.....
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In case it is impossibe is it another way to show aspx pages withing another html page?
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Oct 19, 2010
How can one allow a power point presentation to be displayed on an aspx page?
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Nov 24, 2010
I am using technologies Visual studio 2005, .net frame work 2.0, ASP.NET, C#.NET, MS-Office 2003, Chart Director Tool and Operating system Windows Xp.Iam able to create a power point slide using my C#.net code. But I am not getting how to put Chart image in that slide. Using the below code I am generating chart in my .aspx page.
<script language="C#" runat="server">
protected void Plotgraph_Click(object sender, EventArgs e)
{
[code]...
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Sep 13, 2010
I have several gridviews on an aspx and each has a hyperlinkfield. All of them redirect to another page with a single gridview. I am trying to figure out how to get each hyperlinkfield to redirect to the actual point on the receiving page with the corresponding value. In the sample data below, I need to be able to click on 'def' and open aspx page 2 to the point on the page where 'def' is located. All values still need to be visible. Can anchors be used in gridviews?
aspx page 1:
(gridview1)
hyperlinkfield1
field2
field3
abc f2data1
[Code]....
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May 25, 2010
I'm trying to prevent a "flicker" effect that is occurring on my ASP.NET page which occurs when a user navigates to the page via the browser back button after having navigated away from it. The reason for the flicker is that I'm using an Update Panel which has some content in there on the initial page-load. As a result, when the page is loaded via a back button that initial content is shown very briefly before it is updated with the correct History-aware data.
In order to overcome this I am intending on having the updatepanel hidden (display: none) on inital page load and then show it as long as we don't have any history to deal with. The problem is that I can't find out what to check to determine if there's any history. I can see that the Sys.Application has a _history member but when I'm checking it on page init it is null each time.Does anyone know what I should be checking to determine if there's history to deal with for a page load client-side? And at what point to do it?
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Nov 8, 2010
In building custom controls, I've seen two patterns for using the viewstate. One is to use properties to disguise the viewstate access as persistent data.
public bool AllowStuff
{
get
{
return (ViewState[constKeyAllowStuff] != null) ?
(bool)ViewState[constKeyAllowStuff] : false;
}
set { ViewState[constKeyAllowStuff] = value; }
}
The other is to use private member fields and to override the Load/SaveViewState methods on the control and handle it all explicitly:
protected override object SaveViewState()
{
object[] myViewState = new object[2];
myViewState[0] = base.SaveViewState();
myViewState[1] = _allowStuff;
return myViewState;
}
protected override void LoadViewState(object savedState)
{
object[] stateArray = (object[])savedState;
base.LoadViewState(stateArray[0]);
_allowStuff = (bool)stateArray[1];
}
(I cut out a lot of safety checking for clarity, so just ignore that.) Is there are particular advantage to one method over the other? I can't see how they'd differ much performance wise. Version 1 is lazy, so I guess you save a bit if you don't need that particular value during a pass. Version 1 is also more abstract, hides the details better. Version 2 is clearer about when the data is actually valid and ok to read or modify (between the load and save) because it more clearly works within the ASP.NET lifecycle. Version 2 does tend to require more boilerplate code though (a property, a backing private field, and viewstate handling in two places) as opposed to Version 1 which combines all that into one place.
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Jan 15, 2010
Here's the situation - Most of this ASP.NET Web Forms application (which uses a single master page for all pages) with Forms Authentication, has a standard session timeout, but there are some "modes" where we store an encoded cookie that links the user to their account.
I would like to manually check early on in the page lifecycle for the cookie, and if certain conditions are met, manually re-establish the user's authentication ticket/session.
Where's the best place to do this? Master page Page_Init? Global.asax BeginRequest?
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Apr 12, 2010
I think I summed up the question in the title. Here is some further elaboration...I have a web user control that is used in multiple places, sometimes more than once on a given page.The web user control has a specific set of JavaScript functions (mostly jQuery code) that are containted within *.js files and automatically inserted into page headers.However, when I want to use the control more than once on a page, the *.js files are included 'n' number of times and, rightly so, the browser gets confused as to which control it's meant to be executing which function on.What do I need to do in order to resolve this problem? I've been staring at this all day and I'm at a loss.
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