I want to know if I apply server side validation on a text box then when the validation event fires (I means in which state of page cycle this validation has been done in server side)
It fires after the Load phase, before a button-click happens.
But in such a button-click handler, you need to check the results using Page.IsValid, to prevent handling the click when there is invalid input.
From this page:
Postback event handling: If the
request is a postback, control event
handlers are called. After that, the
Validate method of all validator
controls is called, which sets the
IsValid property of individual
validator controls and of the page.
Related
I have a dropdownlist, in the client side, i have it's on change event. If validation is passed, it's selected inded changed event should be fired(server side). My side, the server event is not getting fired. Autopostback is also set is true.
Any suggestion ?
If you are adding the code from the code-behind (as opposed to in the ASPX or ASCX markup), make sure you add it in the Page_Init event or override CreateChildControls. If you want until the Page_Load event to add it, the ASP.NET has already initialized the control state and view state and then will not be aware that the dropdown exists, so when the postback comes it won't know what control to route it to.
Also, in this case, make sure you are always adding the control to the page, not just when Page.IsPostback==false
Make sure your page code is in autoeventwireup = true.
you can check it in your page design page on top.
if autoeventwireup is set to false your event doesn't fire. auto event will set automatically event so it is necessary to write else you have to set event on initialize state.
can you define autopostback and postback and it's differences and which web server control support autopostback and postback and also the difference between postback and callback?
postback: the page performs a POST request to itself
autopostback: a postback is performed automatically, for example when the selected value of a dropdown changes
callback: a method which is invoked when a certain event occurs such as clicking on a button. It also could have another meaning that a page performs a request back to the server (such as an AJAX request).
A postback is initiated by the browser, and reloads the whole page, usually when a control on the page (e.g. a button) is changed.
With some controls (e.g. Checkboxes), you choose if changing the control should result in a postback. This property is called AutoPostback.
A callback is initiated by java script in the page, and can load/update parts of the page, e.g. by manipulating the DOM.
Controls that support AutoPostback includes:
List item
ListControl
BulletedList
CheckBoxList
DropDownList
ListBox
RadioButtonList
CheckBox
TextBox
PostBack happens when data is send to the server (he page performs a POST request to itself)
IsPostBack helps you to identify if postback happen or not
Autopostback if this property of control is true helps to you post as soon as data change on the contol or some event occur
callback is a special postback, so a round-trip always occurs; however, unlike the classic postback, the script callback doesn't redraw the whole page. ViewState is not updated during a callback, it is for postback.
I know why it's happening and i turned the validation off on the page level, but is there a way to turn it off on the control level?
"Invalid Postback or callback argument . Event validation is enabled
using in configuration or <%# Page EnableEventValidation="true" %>in a
page. For security purposes, this feature verifies that arguments to
Postback or callback events originate from the server control that
originally rendered them. If the data is valid and expected, use the
ClientScriptManager.RegisterForEventValidation method in order to
register the Postback or callback data for validation."
look this post.
Invalid postback or callback argument. Event validation is enabled using '<pages enableEventValidation="true"/>'
in this, i've used Subclass ListBox method. it works...
My ASP.NET form contains a collection of dynamically-created radiobuttons that are created and configured in the Page_Load event handler.
Normally, I process postback data in the Page_Load handler, using the condition:
if (IsPostBack)
However, since the controls that I need to access are created IN the Page_Load handler, the postback data from the previous rendering of the page is lost. To better illustrate the problem, here is an outline of the events as they occur:
1-Page_Load is invoked for the first time
2-An unknown number of radiobuttons are created dynamically
3-The radiobuttons are configured, based on information present on the server
4-The radiobuttons are added to the page's content
5-The user selects an option, and clicks the submit button
6-The Page_Load handler is invoked for the second time
7-The radio-buttons are added dynamically, exactly as before
8-The radio-button that the user checked is seemingly non-existant for processing
It seems like I need to be processing different parts of this in different event handlers. Is there an event that occurs after postback, but while the original radiobuttons are still accessible?
Check out the "Init" events...
http://msdn.microsoft.com/en-us/library/ms178472.aspx
I am having a problem where my button click event is still firing even though my custom server-side validation is set to args.IsValid = false. I am debugging through the code and the validation is definitely being fired before the button click, and args.IsValid is definitely being set to false once the custom validation takes place, but it always makes its way to the button click event afterwards. Any ideas on why this is?
Not sure 100% of the particulars, but to prevent code from continuing, add to your button click event handler:
if (!Page.IsValid)
return;
That will prevent the code from executing.
On Client Side when OnClientClick="return SomeCustomClientCode();" is called, asp.net validators e.g required field validators are disabled and it does not gets listed in validators collection and does not validate the field validated by this validator and page post backs if custom validation passes...
To avoid this explicitly enable asp.net validators in Custom validation code or else where so that it gets activated b4 page postback or in the begiining of custom validation as follows:
ValidatorEnable(document.getElementById('<%=rfvDDLStatus.ClientID%>'), true);
rfvDDLStatus ==> required field validator which was not firing.
ValidatorEnable ==> Client API to enable asp.net validator