Friday, February 29, 2008

How to check if class has been used in Web or Windows application

After a while, I decided to participate in a newsgroups tonight and found an interesting question. "Is there a programmatic way for the class lib to determine what kind of app is running - web or windows". The worst, guy requested official response from Microsoft support and didn't get an answer. After 3 days his question wasn't answered, he re-posted it. So, is there are something wrong? Looks like not.
The simple answer from my side was, to implement following function somewhere in his shared assembly:
public bool IsWebApp(){
return (HttpContext.Current != null);

So, if there is Current HttpContext than function has been called from ASP.NET application and if there is not such an object, function is called from Windows Forms application.
Simple enough.

Tuesday, February 26, 2008

Handling Miliseconds in .NET and SQL Server

Have you taken a look at number of such a questions in online community? It looks like that a lot of .NET developers have a problems reading and updating milliseconds value from SQL Server databases. So what is a real problem here?
Let's take a look at common scenario. Developers read data from a table which has Datetime column ColDateTime. Let's say they are storing values in some DataTable table1. Suddenly, if you want just to print a Value of that field, with


you will get value like '2008/02/26 2:26:53 PM'. But you value in database is actually '2008/02/26 14:26:53.3480'. So milliseconds are missing. The only way to get them is to convert value from database in DateTime variable and then print out that variable:

DateTime dtDbValue = System.Covert.ToDateTime(table1.Rows[0].Cells["ColDateTime"]);

Now, you have a real value: '2008/02/26 14:26:53.3480'

Connected to this is also reverse process, where people lose milliseconds during update. Take a look at following statements:

DateTame dtValue = DateTime.Now;

string sql = "update table1 set ColDateTime = '" + dtValue.ToString() + "'";

-- create DataCommand, assign CommandText and execute.

You will see that your column has been updated with the wrong value. Again milliseconds cut.

People try very often to format ToString method call to looks like:
string sql = "update table1 set ColDateTime = '" + dtValue.ToString("yyyy/MM/dd hh:mm:ss.ffff") + "'";

but this cause an exception on SQL Server side saying that varchar value can not be converted to Datetime type. Strange, and maybe lack of documentation, but the solution is to format your DateTime value with different format - using 3 f and not 4:

string sql = "update table1 set ColDateTime = '" + dtValue.ToString("yyyy/MM/dd hh:mm:ss.fff") + "'";

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Saturday, February 2, 2008

Great Help Authoring Tool

We have just discovered and get impressed with Rolehelp. We are still testing different help authoring tools but this one with their simplicity, great user interface, feature reach capabilities and creation of 7 different help formats simply fascinate us. Of course, we have never wanted to spend 1000$ for such a tool, therefore Roledata offer of 59$ and free demo version with limitation of 50 topics is very, very attractive one. So, if you need fast, simple, free or at least cheap help authoring tool, visit them and you will get one great tool.
I'm sure we will use it in our data and schema compare solution in version 2008.

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