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Designing and Developing ASP.NET 4 Web Apps (Exam 70-519) Tutorials
User Interaction / View State Demo
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Subtitles of the Movie (Designing and Developing ASP.NET 4 Web Apps (Exam 70-519) / User Interaction / View State Demo)
Now let's take a look at a real simple example of View State and I want you to see what it is and how it works. Now notice I have Visual Web Developer 2010 open, I am just going to do a new project and actually rather than confuse you with this look here, let me open this all over again. And this is the way you will see it open up and you'll probably see something that looks like this with the Start Page. I'm just going to click New Website and I'll just click ASP.NET website, we'll do Visual C# and I'll just take the Default File name, it's website 14 in my instance, don't worry about it, if it's different yours and we'll just let it set up our basic default website. If I go to the Design Page, you'll notice that I've got the basic page, it says welcome to ASP.NET. Notice I'm using a Master Page, I have some CSS set up out there for me. Well what I'm going to do, is click right here beside welcome to ASP.NET and hit the Return key twice. Then I'm going to grab a text box, drag it on that top line that I created and then I'll grab a button here and drag it onto that second line that I created. So your web page should look something like that now. Notice I got a text box here and a button here. What I'm going to do first is, let's run this page. So I'm going to click on Run here or Debug if you will and tell it to run without debugging and say OK. Notice it's going to kick off my local web server that's running inside Visual Web Developer environment and notice is there is my text box and there is my button. Well, whatever browser you're running, if you're running the one inside the Visual Web Developer package, you can come over here and click on this little Wrench for Settings and actually this is Google Chrome that's running here. Look at Tools and what you want to do is View the Source on that page. Alright. And so if you View the Source, you will notice that I have something up here, notice there is a View State and there is some data already there. But notice it's in a class called ASP.NET Hidden. All this was put there for me. Now notice there's also some hidden information on Event Validation, don't worry about that, we're concentrating on this right here. Well what is that going to do for us? Well if I type some data in here, like Mark is a very nice person. Okay. That's there from earlier and I click the button, notice that every time I click the button up here, you'll see a little flash. It's actually going up to the web page and coming back and it's hanging onto this data. Well that is because, if I go out and look at this View Source again, go to Tools on mine, yours could be different and go to View Source, this data right here is the encrypted versions of Mark is a nice person and anything else that it wants to keep. Notice the Input Type right here is Hidden, the name is underscore View State and the ID is underscore View State and that is how that is happening. Well if I look at a text box and then come over here and look at Properties, you can see right here that Enable View State is set to true and notice when it's turned on, it determines whether the control automatically saves it's State for use in round trips, that means go to the server, come back. If I turn that off, then that data won't be there when it comes back. Okay. It'll clear every time. So that's a quick example of what a View State does. Is it helpful? Yeah, it's helpful, is it going to solve any of my real serious problems in dealing with State Information for a user on a complicated website? Absolutely not because if I link to a different page, then this View State Information won't follow to a text box there, I'll have to write some code to do that and we'll talk about it, look at a demo on how to do that a little bit later on. But that is what View State is, you'll hear about View State a lot as you read about ASP.NET. It's that simple, it's automatic, it happens for you and if you want to change it or turn it off, you can simply come right here and Enable View State Property and if I was to bring this out to the left, you can say Enable View State Property is how we would control whether we want that on this particular controller. Now if I'm writing a different solution for handling my State and the most likely candidate in most instances for people are going to be some sort of Session State situation, I probably want to come, just turn this off, because I don't want to waste my time having to pass all that encrypted data, especially in the real world, I've probably got more than one text box on my page. Okay. So anyway, real quick demo to help you understand just exactly what's happening when we're talking about View State in ASP.NET.
Tutorial Information
| Course: | Designing and Developing ASP.NET 4 Web Apps (Exam 70-519) |
| Author: | Mark Long |
| SKU: | 34292 |
| ISBN: | 978-1-61866-029-9 |
| Release Date: | 2011-12-31 |
| Duration: | 8.5 hrs / 108 lessons |
| Work Files: |
Yes |
| Captions: | No |
| Compatibility: |
Vista/XP/2000, OS X, Linux QuickTime 7, Flash 8 |
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