Comments by Dmytro Bogachev

Dmytro Bogachev 29-Nov-13 8:26am View

You don't have to make any returns; changes in your function GetExcelData:
1. Inside of function, remove all declarations of datasets;
2. Remove return (you have void return type, check in my answer);
Since your parameters are ds1, ds2, ds3, this is new code of your data filling:
command1.Fill(ds1);
command2.Fill(ds2);
command3.Fill(ds3);
3. And since you declared datasets before passing them to this function, they will be filled with data. You don't have to return them. They are reference types, so when calling function, they are passed by reference. Here is link about passing parameters in C#, and you can find there info about passing by value and passing by reference:
http://msdn.microsoft.com/en-us/library/vstudio/0f66670z.aspx

Dmytro Bogachev 29-Nov-13 7:05am View

There is something we're missing about your question. Control should be initialized already on Page_Load. Maybe you're using Custom Controls and your link button is in custom control, maybe there is some issue about cache, if you use it, but anyways it is not about code you posted here. I suggest you open new question with brief description of your current page structure, which will ask, why lnkUrl is null during Page_Load event.

Dmytro Bogachev 29-Nov-13 6:04am View

One of possible reasons - this control is not yet initialized. What is the event (Page event), in which you're having code, that throws exception?

Dmytro Bogachev 29-Nov-13 6:00am View

So your problem is not in above code, it is correct. Show please code, where you're getting lnkUrl. Basically it's about this control.

Dmytro Bogachev 29-Nov-13 5:53am View

Did you try Debug? What is exact line of your exception? There are 2 possible points of failure in above code, Session["ddlCountry"].ToString() - if ToString() for some reason returns null (and I don't see reason for this behavior) and if lnkUrl.Text is null - this is also weird.

Dmytro Bogachev 29-Nov-13 5:39am View

Let me disagree with you. My answer is similar in Session part. And null-value Session object might be one of reasons why there is such problem. You CAN compare to null, as in your case, but here is what happens in original code:
string s = null; //Session["whatever"] is null
s.ToString(); // And exception

Dmytro Bogachev 28-Nov-13 7:47am View

Threading itself and locking in particular indeed affects performance, decreasing it. But threading, from other side, makes your solution scalable and responsive. Sometimes you can rework your solution to work without locks, but sometimes, as in your case, you must lock objects to make solution work correctly (or to make them work at all). While lock is in affect, other threads cannot access locked sections of your code, so they will be blocked. Anyway, threading is topic for some academic book, not for small response)

Comments by Dmytro Bogachev (Top 7 by date)