Categories
.NET C#.NET Programming

Extensions Method in .NET

Recently I use extension method in C# project. I knew those for years, but really never get a chance to use them where they are most effect. I have couple of extension method in my project, such as ToInteger(), for a string to convert a String to Integer, which I used more frequently in my project. But that doesn’t seems a good use of technology to me.

But I now found a perfect use for extension method. i.e. I was upgrade my code from old ASP.NET project to MVC and for this I am making a class library of all objects. Now, this scenario need me to make a conversion from old enum to new enum  which are now part of namespace of my class library, rather than sitting around in App_Code folder. Here I make a extension method that convert a OLD enum to new name space base. This ease lot of my works.

Method goes like:


public static NewType GetSaleType(this OldType s)
{
	NewType r = NewType.Regular;
	switch (s)
	{
		case OldType.BK: r = NewType.BK; break;
		case OldType.IL: r = NewType.IL; break;
		case OldType.MM: r = NewType.MM; break;
		case OldType.PC: r = NewType.PC;break;
		case OldType.Regular: r = NewType.Regular; break;
		case OldType.Trigger:r = NewType.Trigger; break;
	}
	return r;
}
Categories
.NET ASP.NET C#.NET VB.NET/VB

ASP.NET: Why my cookie is not saving

Funny, today after years I thought to finally use Cookies in one of my project. It is probably my first attempt to use Cookie in ASP.NET in last 5 yrs. WOW, that is amazing. Anyways, I just notice one thing and thought it might help any first timer, so here is the key note I want to share. In ASP.NET if you want to read Cookie, use REQUEST.Cookies, but if you want to add new Cookie use RESPONSE.Cookies. This is very minor difference and I really waste 30 minutes before I release I was using Request.Cookies to add new cookie, but it won’t get added that way.

Categories
Article ASP.NET Bookmarked C#.NET PHP Programming VB.NET/VB

WKHTMLTOPDF: A Free PDF solution

As any other developer we often find it difficult to get a Website to print something accurately, specially when printing labels for mailing as they are outside the default print area for most browser and no client want to adjust or memorize the print setting to adjust them manually. Also it doesn’t make sense to relay on client to do adjustments.

So the only universal solution I found is.. of course PDF files. But how do I create PDF. Well easy enough use some library. I did that I use iTextPDF very good Library that works for my C# project well for couple of years. But then what is the problem now? Well iTextPDF is now have commercial license at ridiculous pricing in fact it is now most expensive to any other paid software. Yet another Open Source project going paid on success. 

Also, there is a problem with library like iTextPDF that they need you to draw each and every element programmatically more often or not. And you find yourself caught in a web of long written code. I remember one of my report’s PDF generation code goes 1000 lines. I hate it. So, the best solution is to Generate PDF from a HTML source. We can handle HTML much better way and rather easily with our skills as web programmer. And even a designer in team can change PDF design giving time for programmer for other work. 

In this regard I look for free alternative of iTEXTPDF, which does have HTML parser to generate PDF from HTML file, and my search for now ends on http://code.google.com/p/wkhtmltopdf/ (wkhtmltopdf ) project. A Simple Executable that I can call from a my code to execute and it does the parsing. 

It is not really a good idea to call it through web page, but we should create a Windows service and use it there, but I have successfully test it to work on web server with quite a load and at least with my limitation to access Windows Service I can live with it running through HTML page, after all my PDF is just 1-2 page and it works fine. Will post code for it some other day. But do try it if you want a good and quick solution to your problem.

Categories
.NET ASP.NET C#.NET Concept/algorithm Database VB.NET/VB

Static Object in ASP.NET

Recently I found a problem in one of application we developed. Here my colleague use a Static SqlConnection object through a class in his code. He did that to save his effort of writing and Connection everytime. Everything works great during our development and online reviewing. However as soon as we lauch website in beta mode, it start creating problem which seems bit random in occurance and hence were hard to track. During this time I get involve in the project development and I was not very big fan on Static object and start to think against that code, which looks good to me at first. However for some reason I miss the basic of C# and ASP.NET and hence it took a while to recognize the problem was indeed the static code. So for those who did same mistake here is explanation of why Static object didn’t work in ASP.NET for connection.

When ASP.NET application is first called the complete code is loaded in Memory, specially the pages in App_Code folder and they act as part of web server and not as standard PHP site where they run and loaded on each request. Hence, once this happens all static object become static in memory for each and every request your server will get. This is indeed good way to share information between all User and all request, if that help your case. But in most general case you never want to share information between user in this dynamic method, which is not permanent. Anyways, for connection it really doesn’t make a difference if you share the object as you anyways want to open connection and close it as soon as you are done. In most case you have 1 simple insert or fetch query to run. And in a website with several users at a time it hardly make a difference as Sqlconnection are open and close in jiffy and took less than 1 second in most cases. For a shopping cart which has 100 -200 order per month this case will work just fine.

However, since connection is shared, there is every possible chance that if you fire a SQL query for say Reader, it get shared with some user on some other session and this is what you don’t want. It happens to our project when we have Bulk CSV upload which usually take 30-50 seconds, but if someone during this time fires and open other page of website they start to get random Database related errors. From SqlReader is close to field “Xyz” is not available, as they tend to share the connection with other requests.

Hope you avoid those problem. The colleague who did this in our project is not working with us anymore, but hey, where ever you are , please don’t punish us like this again !!!