I have a gridview within an update pannel. The gridview contains controls that need to throw async postbacks. I have them registered with the scriptmanager during row bind, but I don't see their change event getting handled by anything. The gridview's rowcommand event doesn't fire. Where should I catch these postbacks?
You have to manually specify Async and Full Postback triggers .
In this article explains how to set AJAX UpdatePanel Triggers i.e. PostBackTrigger or AsyncPostBackTrigger for Button or LinkButton placed in GridView within AJAX UpdatePanel.
hope this will help you
You should wire up the event handlers just like you would if you wanted full postbacks. The fact they are partial doesn't change how the event fires from that perspective.
If the events aren't firing, then the triggering mode of the update panel may be set incorrectly.
Related
I have dropdownlist with some data provided by the page load with calling to a server-side function. On that dropdownlist selectedindexchanged event, I do need to call to get the value of selected index without autopostback. it works only when autopostback is set to true.
without autopost back you can't call selectedindexchanged event. If you dont want to refresh the page you can use UpdatePanel or You can use Ajax call.
I am trying to take advantage of the page lifecycle in Asp.NET so that I don't bind to my datasources more than I actually need to.
This has led to the following problem. I have an ObjectDataSource, GridView, and a button on my page. The button adds a record to the database, which should be picked up by the data source and presented on the Grid. The problem is that the item is not showing up on the gridview until I refresh the page.
I can solve the problem by calling GridView.DataBind() in my button's event handler, but this goes against what I understand about the .NET Page Lifecycle.
Based on this article, the lifecycle should be as follows:
In addition the article states that the Databinding event is "Raised after the control's PreRender event, which occurs after the page's PreRender event."
So, my button click event should fire first, during the Event Handling phase. It should add the record the database.
Next PreRender should be called on the controls.
Finally DataBind should be called on the controls, and the Grid should update to capture the new record.
Yet this doesn't seem to happen. What am I not understanding?
I think the issue is that your viewstate is not enabled on your GridView. This is what I experienced, but then I also had to call DataBind() on the GridView from the page PreRender event if the request was a postback to get the data updated in the GridView on postback.
Edit:
It would help to understand the issue and context better if you could post the source code of your page (aspx + codebehind). How and where do you connect your GridView to your datasource? Statically in markup or dynamically? Do you make any calls to page.DataBind()? ... These things may influence the behaviour of the GridView.
I have two update panels and in the second update panel i have asp.net button and onclick of the button in codebehind i have disabled it like btnAddSecurity.Enabled = false;
When I disable the button i enable a cancel button before it and on cancel button when i try to enable the btnAddSecurity.Enabled = true it simply doesn't work. Both of my updatepanels updatemode is conditional. what is the problem?
thanks
I am assuming cancel button is in the different updatepanel. Then add follwing line to your button click code..
UpdatePanel1.Update();
For more information refer this..
How UpdatePanel Controls Are Refreshed
If the UpdateMode property is set to Always, the UpdatePanel control’s content is updated on every postback that originates from anywhere on the page. This includes asynchronous postbacks from controls that are inside other UpdatePanel controls, and postbacks from controls that are not inside UpdatePanel controls.
If the UpdateMode property is set to Conditional, the UpdatePanel control’s content is updated when one of the following is true:
• When the postback is caused by a trigger for that UpdatePanel control.
• When you explicitly call the UpdatePanel control's Update method.
• When the UpdatePanel control is nested inside another UpdatePanel control and the parent panel is updated.
Assume I have an asp:GridView with some customer information. On that page I also have a button which allows me to add a new user to the GridView. When I add the click the user, I databind the gridview again in the button click. Correct me if I am wrong, but if the asp.net lifecycle or at least part of it is in the following order:
page_load
Hookup event handlers such as my button click
page_preRender
Does this mean that if I put the databinding for the gridview in preRender, that is the only place I need to worry about calling it. I can remove it from the button click. This is what I think, but I am not sure if my thinking is correct, so I would like some more insight as to the benefit of putting code in PreRender as opposed to PageLoad
By PreRender, you assume that most logic in the page that would affect the binding result has been completed (usually in Page_Load, but anywhere earlier really).
Controls in the .Net framework by default do their binding in the PreRender event (makes sense, bind to the datasource at the last possible moment...could be that you changed the data 400 times earlier in the lifecycle). Here's the full layout of the 2.0 lifecycle for reference.
PreRender - Before this event occurs:
The Page object calls EnsureChildControls for each control and for the page.
Each data bound control whose DataSourceID property is set calls its DataBind method. For more information, see Data Binding Events for Data-Bound Controls later in this topic.
The PreRender event occurs for each control on the page. Use the event to make final changes to the contents of the page or its controls.
I forgot to mention this asp.net 2.0.
The user control has a unique id and it is loaded in the PageLoad event.
The user control is loaded into a panel and the panel is inside of a webpart.
The dropdown has autopostback set to true.
EnableViewState = true on the dropdown.
The ListItems are created in the dropdowns pre-render event method.
This is why I don't understand why it is not firing, the dropdown is the only thing that causes postback on this user control.
The event methods for the dropdown should occur since the user control is loaded in the page load method on postback again right?
Make sure there is no OnLoad or PageLoad event that is rebinding the datasource of the dropdown list. Rebinding the data with a new set of data may cause the clickhandler to not ever get executed.
make sure you have if (!Page.IsPostBack) around dropdownlist.datasource = and dropdownlist.databind()
I am not sure if this is your problem, but it is the most common.
Try with EnableViewState set to
true for the DropDownList
If the ViewState is set to false, on post back the selected Index gets back to default which is normally the first Item. First item, if selected, does not cause SelectedIndexChange event to fire