Question

I have added a textbox, a dropdownlist, a checkbox, a button, and an update panel to a web page. In it’s cs file, when the second item in the dropdownlist is selected, panel1 becomes visible, else non are visible. Here is the sequence of the control. The update panel is used to refresh the particular part. Does it right way?

//Textbox1
//Textbox2
//Textbox3
//dropdownlist having autopostback= true
//update panel start
//checkbox1
//checkbox2
//checkbox3
//simple panel non visible (panel1)
//checkbox4
//checkbox5
//checkbox6
//checkbox7
//simple pannel end
//update pannel end
//button

The Scriptmanager is added in master page. I am not getting a syntax or any other error. I am asking about logical way.

Answer 1

The way updatepanel works is during postback, the complete page is sent to server for processing. The regular Asp.Net page life cycle is executed. Its while sending the response, the markup of the content which is inside the update panel is sent.

So its always recommend to have more number of update panels containing set of controls, rather than encapsulating all the controls in one updatepanel. Remember that update panel only gives little performance benefit while sending the response.

In your case, if there is some business logic involved on selection of dropdown, then you can go ahead and use Update Panel. If its all about showing/hiding the panel, then you can do the same via JavaScript/jQuery.