'Why Master Page is set in Pre_Init event of Page in Asp.Net?

Why we set master page in Page_Init event. We have other events in page. For me one reason could be that master page does not have Pre_Init and other could be that Init of Page occurs before master page Init. Correct me if I'm wrong.

c++sharpasp.net


Solution 1:[1]

Masterpage doesn't have PreInit method.

Master pages inherits:**System.Web.UI.MasterPage** and as per the design of this MasterPage class no such PreInit event is defined for this class.

Master pages are derived from Control class as seen in below hierarchy:

System.Object
  System.Web.UI.Control
    System.Web.UI.TemplateControl
      System.Web.UI.UserControl
        System.Web.UI.MasterPage

Therefore as can be guessed now, Master pages behave and in essence are treated like a control and have events similar to other asp.net server control

Solution 2:[2]

Because all things that 'dynamically' modify page controls have to occur there. This is where the page is rebuilt (form objects) with out request. Then things like page_load occur, after all objects are made.

Winforms analogy - if you are familiar with that - page_init is analogous to the InitializeComponent in the New (NOT REALLY SAME - just analogy please).

Only due to the nature of the web (at least round-tripping to the server), it can't possibly work like winforms (or WPF or even a SPA web app with a js/DOM UI and webapi backend) so has to rebuild the form's objects EVERY request.

Why does only the PAGE have page_init and not master page? Well as prateek says, but in addition, the rebuild of the page has to be control from just one spot. There is just one request. Controls can init, too as the page init process calls them in turn.

You have asked a question with a complicated answer.

Here is a good chart of what's going on... http://www.codeproject.com/KB/aspnet/ASPDOTNETPageLifecycle.aspx

alt text
(source: codeproject.com)

Note how the postback data is loaded into the controls BEFORE the page_load, too - this is why it's too late to do anything big in the page load. You can't possibility get anything back from the user that was changed there (unless you go right to the postback data). The picture shows how ASP tries to 'fake' an event - driven UI on a client/server web architecture (e.g., 'event related logic' calls your 'events'). There is no such thing in client/server asp UI!

Solution 3:[3]

As a master page is the default screen throught the application ,it should be initialized first before the child pages.In order to get initalized earlier it is done in pre_init where the master page is loaded.later in Init() all the child pages are loaded regarding to that master page.

Solution 4:[4]

During the ASP.NET page life cycle, the initialization is also included on the master page. This is where the design and all the controls that are on the master page will be available before the page is loaded, which will be the "Load" phase of the page life cycle. If the master page is not initialize, you would get a page with no design, except the information on the page.

"During page initialization, controls on the page are available and each control's UniqueID property is set. A master page and themes are also applied to the page if applicable. If the current request is a postback, the postback data has not yet been loaded and control property values have not been restored to the values from view state."

https://msdn.microsoft.com/en-us/library/ms178472.aspx

Sources

This article follows the attribution requirements of Stack Overflow and is licensed under CC BY-SA 3.0.

Source: Stack Overflow

Solution Source
Solution 1 Prateek Gupta
Solution 2 Glorfindel
Solution 3 karthik krishna
Solution 4

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