Thanks for the introduction :-)

I don't have any code that does this, though I'll put it on my list.

Dynamically Adding conrols in ASP.NET somewhat difficult becuase the added controls are not added to any page state mechanism.

You certainly can inject additional DropDowns programatically into the page but you'll need to recreate those additions in the page_init method so postbacks don't remove them.

I don't quite understand about this tool needs to use Web Service to pick up data from database. How come this extender doesn't provide DataSourceID attributes to just call the SQLDataSource control to get the data feed instead of going through so much coding with Web Service?

I just think this AJAX control is just making developer to create more codes rather than simplify the coding process for having a cascading dropdown control. We can have a series of cascading dropdown controls by using SQLDataSource wrapped inside the UpdatePanel control, why would we need this AJAX one which requires us to go through Web Service to get data from the database.

Please correct me if I am wrong.

Thank you,

Erik

Thanks

Radu

Very very good video.. this has helped me alot.

But i need to know one thing. What if the javascript is turned of the ajac-cotrols doesn't work!!!!

How do I handle so the page works as standard aspx if javascript is disabled. Are there any examples on that??

1.) UpdatePanel is WAY less efficient since it does a complete page postback and executes the complete .aspx pafe lifecycle.

2.) YOu can execute much more server side logic than a simple parametric database query.

As to JavaScript.....

If the user doesn't have JavaScript enabled then there is no AJAX. You need to post back after every selection (which you can't do automaticaly since there is no JavaScript) and build an updated page each time.

But what if javascript is enabled. It retrives data two times.. one from the Load_event(Serverside) and the secondtime it gets from the Servicefile(constructed for AJAX-controls)????

Thanks

If JavaScript is on then you just do ASP.NET AJAX.

Just use the code here:

<a rel="nofollow" target="_new" href="http://www.codeproject.com/KB/scripting/Javascript_Detection.aspx">www.codeproject.com/.../Javascript_Detection.aspx</a>

I'm trying to implement Cascading DDLs with DB using  Categories and Products tables of Northwind db.

I've two DDLs - category & products and 2 CCDs - ccdCategory and ccdProducts.

I'm getting [Method Error 500] when page loads.

I'm using Web Developer 2005 Express Edition.

Can you please tell me why this happens?

But web service is working correctly.

I saw your vedio and was trying to implement Cascading DDLs with DB using  Categories and Products tables of Northwind db.

I've two DDLs - category & products and 2 CCDs - ccdCategory and ccdProducts.

I'm getting [Method Error 500] in Category DDL when page loads.

I've set ServiceMethod & ServicePath properties correctly.

And also the required attributes in web service file.

I'm using Web Developer 2005 Express Edition.

Can you please tell me why this happens?

But web service is working correctly.

I never thought that implementing ajax in .net is soo easy and interesting.Ya Microsoft makes every thing powerful and easy to implement.I m proud of Microsoft.

And Joe all ajax videos posted by u are just fantastic.

This will help many.Thank u very much.

can u tell me difference between "Atlas" and "Ajax Extension 1.0". Which one should i install to use??

waiting for reply.............

I's so rewarding when folks are able to learn from the work I/we do.

BTW - Atlas was just the project name that we used before we released. You should be using the "ASP.NET Extensions for AJAX 1.0".

To Jnaneshwar: You're seeing a 500 Server error ?

Ths is useually an error in the Web Service code and can be seen if the Service Class is not decorated with the ScriptService attribute.

Thanks, Walt

I'm totally new in AJAX, from this video, I would like to know the code:

Public Fuction GetMakes(byval knownCategoryValues as String, ByVal category As string) As CascaddingDropDownNameValue()

'implementing

End Function

1) Is that the knownCategoryvalues is the reserve word?

2) the function is pass in 2 parameters from where?

3) from the implementing part, the makesValues.add () NewCascadingDropDownValue (row("...").tostring(), row("...").tostring())

the carId return parameter is to pass in to the cascading model's as knownCategoryValue?

4)from the next webmethod: Model

stringDictionary is used when we need to get parameter from parent control? for database?

5)what is that means by Cascadingdropdown.ParseKnownCategoryValuesString(knownCateg oryValue)?

6)if my MakeID is a string value,in the if method, i should put "...or (Not char.tryParse(kv("Make"),makeID)) Then ..."

Hope to hear you soon.Thank you

1) the knowCategoryValues a parameter that sent from where? Shall we use another name to replace it?

2) the string dictionary is act like an abstract table to get values knownCategoryValues from the parent control?

3)instead of use integer as a makeID, I use string as my make ID, then may i write "...Or (Not Char.TryParse(kv("SupplierID"), suppID))) Then ..."?

Hope to hear reply from anyone of you. Thanks.

I have wasted to much time trying to trouble shoot this.

   I have done this,"Ths is usually an error in the Web Service code and can be seen if the Service Class is not decorated with the ScriptService attribute."  But still get Method 500....   Should I abandon the Ajax thing and go back to the old way?  I hate to do that, but it looks like I might.

   I am curious, I saw your video of the debugging JavaScript in VS-2008.  I received a free copy from DevConnections and I was thinking of installing it.  Would I be able to trouble shoot this better if I had VS-2008?