Using Page Load and Page PreRender in ASP Net

Question

I see some people are using Page Load and Page PreRender in same aspx page  Can I exactly know why do we need to  invoke both the methods in same asp net page   Please see the code below       protected void Page Load object sender  EventArgs e                try                       dprPager ButtonClickPager    new EventHandler dprPager ButtonClickPager                if   Page IsPostBack                              InitPager                                     catch  Exception ex                                   protected void Page PreRender object sender  EventArgs e                erMsg Visible    string IsNullOrEmpty lblError Text

User · Answer

The major difference between Page Load and Page PreRender is that in the Page Load method not all of your page controls are completely initialized  loaded   because individual controls Load   methods has not been called yet  This means that tree is not ready for rendering yet  In Page PreRender you guaranteed that all page controls are loaded and ready for rendering  Technically Page PreRender is your last chance to tweak the page before it turns into HTML stream

User · Answer

Processing the ASP NET web-form takes place in stages  At each state various events are raised  If you are interested to plug your code into the processing flow  on server side  then you have to handle appropriate page event

User · Answer

The main point of the differences as pointed out  BizApps is that Load event happens right after the ViewState is populated while PreRender event happens later  right before Rendering phase  and after all individual children controls  action event handlers are already executing  Therefore  any modifications done by the controls  actions event handler should be updated in the control hierarchy during PreRender as it happens after

User · Answer

Well a big requirement to implement PreRender as opposed to Load is the need to work with the controls on the page  On Page Load  the controls are not rendered  and therefore cannot be referenced

User · Answer

Page Load happens after ViewState and PostData is sent into all of your server side controls by ASP NET controls being created on the page  Page Init is the event fired prior to ViewState and PostData being reinstated  Page Load is where you typically do any page wide initilization  Page PreRender is the last event you have a chance to handle prior to the page s state being rendered into HTML  Page Load  is the more typical event to work with

User · Answer

It depends on your requirements   Page Load   Perform actions common to all requests  such as setting up a database query  At this point  server controls in the tree are created and initialized  the state is restored  and form controls reflect client-side data  See Handling Inherited Events   Prerender  Perform any updates before the output is rendered  Any changes made to the state of the control in the prerender phase can be saved  while changes made in the rendering phase are lost  See Handling Inherited Events   Reference  Control Execution Lifecycle MSDN  Try to read about   ASP NET Page Life Cycle Overview ASP NET  Control Execution Lifecycle  Regards

[asp.net] Using Page_Load and Page_PreRender in ASP.Net

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