LINQ to Entities does not support Contains() method

We are using .NET Entity Framework in our project and today I wrote a LINQ to Entities query to fetch records from table A if corresponding records are not found in table B. Let us take example of customer orders scenario. I want to get all the customers who don't have a order in the Orders table. What I needed was "NOT IN" or "NOT EXISTS" SQL equivalent in LINQ to Entities. I knew that we have Contains() method in LINQ to SQL which is equivalent to NOT EXISTS in SQL. So, I tried following LINQ to Entities query to return all the costumers who don't have a order in the Orders table:

from c in context.Customers
where !( from o in context.Orders select o.CustomerId ).Contains( c.CustomerId )
select c

I was confident this would work, but no the above query did not work!!. I got an error that LINQ to Entities does not support Contains() method. It is frustrating to know that the same Contains() method works in LINQ to SQL but not in LINQ to Entities. Why not support such basic functionality.

I had other frustrating moments with LINQ to Entities too. I prefer to just use LINQ to SQL and stay away from LINQ to Entities.

The NOT EXISTS equivalent in LINQ to SQL

Here is a sample LINQ to SQL query to return all the customers who don't have an order in the Orders table:

var query =
from c in Customers
where !( from o in Orders select o.CustomerId ).Contains( c.CustomerId )
select c;

Useful Keyboard Shortcuts for Microsoft Visual Studio

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Firebug for Firefox

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Download Firebug from here: http://getfirebug.com/

Internet Explorer Developer Toolbar

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Silverlight error: The debugger cannot continue running the process.

Today I got this error while debugging my silverlight application and the debugger just crashed without any useful error information. I got this error when the debugger crashed:

"The debugger cannot continue running the process. Process was terminated."

After doing some debugging and research I found this thread online where in many people had the same issue because of recursive call in class property:

http://social.msdn.microsoft.com/Forums/en-US/vsdebug/thread/f9b08dd4-8d20-4104-9a24-9f002caceb48/

I looked at my code and indeed I had a recursive call in one of my property by mistake.

private bool isUser;
public bool IsUser
{
get { return IsUser; }
set
{
IsUser = value;
OnPropertyChanged( "IsUser" );
}
}

As you can see in the above code my getter was recursively referring to IsUser property itself instead of the field isUser. This was just coding error but it took some time to figure out the root cause as the debugger was crashing without proper error information.

Date format in WPF/Silverlight

Here is an example for formatting date in WPF (Format: MM/DD/YYYY):

<TextBlock Text="{Binding CreationDate, StringFormat=\{0:MM/dd/yyyy\}}" />