The ASP.NET Page Cycle

Being a consultant, I have worked with a lot of other consultants - professionals within their domain. It has struck me how few of the ASP.NET developers have a clear understanding of the ASP.NET page cycle, something I think is crucial to be able to write effective code. Given this experience, I have compiled a quick cheat-sheet that illustrates some basic, important, points. Please note, however, that what you find below is a non-exhaustive, simplified, list.

The below page sequence is valid for instances of Control (Page inherits from Control):

  • Page_PreInit
  • Page_Init
  • Page_PreLoad
  • Page_Load
  • EVENT HANDLERS, eg. Button1_Click
  • If Page.Visible Then Page_PreRender

This means, that Page_Load always runs. If you have code that decides whether or not a page/part of a page/control is shown that is dependant on another control, put that code into Page_PreRender.

Example: 

Public Sub Page_Load( ... )
  If Not IsPostBack Then
    LoadRegionalData()
  End If
End Sub

Public Sub Button1_Click( ... )
  _blnLoadHugeProductList = False
End Sub

Public Sub Page_PreRender( ... )
  If _blnLoadHugeProductList Then
    gvwProductList.DataSource = GetHugeProductList()
  End If
End Sub

Tip: If you have a bunch of user controls on a page, they will all load EACH TIME the page is loaded, even if they are hidden. To prevent this, remove them from the control collection in Page_Load of the owning page.

Comments

Post a Comment

Popular posts from this blog

Auto Mapper and Record Types - will they blend?

Image
TL;DR: Yes, they will. Thank you for your time. 😄 Background At Redgate, engineers enjoy a great benefit in that we get are expected to spend 10% of our time to improve on our craft.  Having suffered this week with manually having to copy a bunch of properties from a domain object to its HTTP representation, I decided to spend this week's 10% time to see if I could answer the following questions: Can use AutoMapper to simplify mapping between two types?  Does it also allow me to map between a regular type and a record type? What about the other way around? Can I use this to reduce the maintenance burden in my product? Mapping between two types [automapper fundamentals] To started and get a basic mapping done, created a .NET 5 ASP.NET Web API project, added the below package references and configured automapper : < PackageReference Include ="AutoMapper" Version ="10.1.1" /> < PackageReference Include ="AutoMapper.Extensions.Microsoft.DependencyInj
Read more

Unit testing your Azure functions - part 2: Queues and Blobs

In our last installment , we discovered how to start unit testing our Azure Functions, looking at the HTTP Trigger (and evaulating the function's HTTP response). This time, we'll take a look at using the QueueTrigger, getting supporting data from table storage and outputting Blobs. Yup, I'm tossing you into the deep end! What are we trying to accomplish? This time, we will test a function that performs some arbitrary business logic on bank accounts. The function responds to a storage queue request, logs each command and ensures that each received command is executed exactly once. Almost like a real-world function, huh? ;-) In the function above, we are introduced to three types that we need to deal with in our unit tests - the IQueryable interface, IAsyncCollector and the CloudBlockBlob concrete type. IQueryable is easy enough to work with: Introducing the Testable Async Collector When I first started exploring this topic, I figured I could just use my favourit
Read more

Testing WCF services with user credentials and binary endpoints

Image
This article discusses the following error messages that you might receive from a WCF service An error occurred when verifying security for the message HTTP/1.1 415 Cannot process the message because the content type 'application/soap+xml;charset=UTF-8;action="..."' was not the expected type 'application/soap+msbin1' When doing analysis work on existing services, invoking them in a safe test environment is a handy way of getting an understanding of their operations, especially if the documentation has gone missing (or was never written). SoapUI is a tool that can be used to test WCF Services, but did you know that Visual Studio also comes with its own set of tools? Let's start with SoapUI, which is available from  http://www.soapui.org/ . Its operations are quite straight-forward; however, you might run into issues when trying to access services that are protected by user credentials, or when accessing services with binary endpoints. I
Read more