Monday, March 26, 2012

PageRequestManager : Whats the difference between doPostBack and _doCallBack ?

I want some parts of my web page refresh after a focus or changed event being made on a TextBox. What I want to acheive is get back to the server to do some code. I check the PageRequestManager and saw to way to make a postback to the server. What I want to do is get back to the server like I put a submit button without the whole page refresh. Some advices on that would be really appreciate !

It's not overly clear what your trying to do. Are you currently using UpdatePanels? If not, look into them:

I know it's not clear. I'm sorry. I'll try to explain more clearly.

On a client event like OnFocus or OnBlur or OnChange, I'll check some client state for the input (TextBox) and take decision if I need to get back to the server to refresh some part of my menu. I try to implement a sort of contextual menu. So, when some part (say inside panel1) got focus, I want to make an ajax request to add some stuff to the menu. When the panel lost focus, maybe I'll switch the visibiliy of some parts of the menu on the client side or got back to the server to do some job.

I'm building a sort of UIManager. This Manager need to check some client state(hidden field) and decide to get back to server if I doesn't have all the state it need to add some part of the menu for the contextual part.

So, I put the menu inside and UpdatePanel UpdateMode=Always. When a control (maybe TextBox, RadioButton or panel) got focus, maybe I need to get back to the server. I want to know if it's necessary to put the control inside and Update Panel or I can write some code to submit the form and use eventArgument to know what I have to do...

I hope is it a little be more clear. I appreciate a lot the time you take to help me !


Thank you for your post!

Based on my understanding, you just want to refresh the updatepanel via javascript(e.g On a client event like OnFocus or OnBlur or OnChange).

Check out like this:

use __doPostBack to refresh the UpdatePanel

If you have further questions,let me know.

Best Regards,


Thank you for this great anwser. It's really what I was searching.

I have another question. I need a way to pass parameter from the client to know what to do when the page refresh on the server. For example, when the TextChanged occured on the TextBox1, I want to update some parts of the menu. Is it a good approach to pass parameter on the EventArguments of the __doPostback ? And which format do you recommand I use ? Or can you recommand me another way of doing that ?

function TextChanged(){ __doPostBack('ClientAjaxComm','');}


It is a good approach to pass parameter on the EventArguments of the __doPostback.

Or you can store something into something hiddenfield,and get them at the server side.

It is up to you to which approach you use.


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