Chapter 4: State Engine

arius · August 10th, 2013, 09:42 AM

Following one of the Try it out exercise I set EnableViewState="false" for a label control. In the browser, the label's text property is set with some code. I then do a postback and the text property value returns to its original value as expected.

However the refresh button on the browser seems very interesting. I click that and the value of the label is preserved. It does not go back to its original value even though I turned off viewstate for it. Why is that ?

Thanks

Imar · August 11th, 2013, 06:17 AM

Hi there,

Which browser do you use? Maybe you're just getting the same page served again? What happens when you click Refresh while holding down control (or press Crl+F5 or Ctrl+R).

Cheers,

Imar

arius · August 11th, 2013, 06:41 AM

Using google chrome. When I press ctrl-R a dialog question box appears asking:

"The page that you're looking for used information that you entered. Returning to that page might cause any action you took to be repeated. Do you want to continue ?".

So I click Ok and the page refreshes. But I noticed something I did not before--the label text is slightly different, so this code gets fired again when refreshing:

Code:

Label1.Text = DateTime.Now.ToString();

I am guessing that firing the same code again when refreshing is a browser feature? and not an ASP.net feature?

Thanks so much

Imar · August 11th, 2013, 06:56 AM

Yes, most, if not all, browsers have this to avoid sending the same post request twice. Imagine you just paid something on an eCommerce site and then refreshed the page. That means you could be paying twice. Browsers help you prevent this from happening by asking you for confirmation.

When you confirm, you re-execute the last action: in other words, it's as if you click the button again and thus the label gets updated.

Hope this helps,

Imar

arius · August 11th, 2013, 07:20 AM

Thank you Imar