Arnold Matusz's Blog

The .NET Framework 2.0+ comes with a set of functionality for easily building security enforced web applications mainly with the ASP.NET Membership API and the Security web controls. The Membership class has most of the feature one would need with user management, and because it is based on a Provider Model you can write a provider for any Database you wish.

While working on an intranet application I often faced the following situation. Several people were online, logged in, when I needed to upload a new version of the web application. Because I personally know all the people who have access to this application it’s important for me to see who is online so I can announce them before taking the application down and uploading a new version. » Continue reading ...

LINQ to Entities does not recognize the method 'Int32 ToInt32(System.String)' method, and this method cannot be translated into a store expression.

This is a shortcomming of LINQ to Entities, and indeed the ADO.NET Entity Framework at the current release! The reason for a similar exception message is that in queries on the Entity Framework, custom methods and extensions methods cannot be translated into store expressions.

There are workarounds to still enjoy LINQ to Entities and as an example please read the following: » Continue reading ...

Most people think that by calling OrderBy().OrderBy() will solves the problem of ordering a sequence by multiple fields. Well I'm dissapointed to announce this is not true because the second call overwrites the ordering clause specified in the first one!

First of all lets analyze the architecture of a LINQ ObjectQuery. The important peice is what it actually returns, namely: an IQueriable object! This IQueriable interface implements the IEnumarble interface which we are normally used to use when creating an ObjectQuery. » Continue reading ...

The InvalidOperationException: Sequence contains no elements exception is thrown whenever you try to retreive an element from an empty sequence. This generally happens when you call First on an empty sequence. What I think about for this situation is that I'ld need a method which would return null if the sequence is empty and the first object (maybe the only object) in the sequence otherwise.

In this case the call of FirstOrDefault is recomended. Although after a few searches I've found something similar: we could Single or SingleOrDefault instead of First. Calling these methods is almost exactly what First does except ... this will generate another exception if the sequest contains more elements: InvalidOperationException: Sequence contains more than one element. But the convenient factor is that it quietly returns the single element in a sequence, null of the sequence is empty and the above mentioned InvalidOperationException: Sequence contains more than one element. » Continue reading ...