Codelab Blog » Linq

OrderBy making null records come last Entity Framework and Linq

Tim — Wed, 27 Jul 2011 11:45:02 +0000

Ever want to sort your result set but make sure the records with a null sorting column appear last?
See the example below

var results = (from x in EntityObjectContext.MyTable
select x
into grp
select new
{
mydata = grp,
myid = grp.id,
mysortingentity = grp.mysortingentity
}
).OrderBy(x => sortingcolumn == null).ThenBy(x => x.mysortingentity.Name).ThenBy(x => x.myid);

Watch this space, this can easily be transformed into a Extension Method. Check out this link http://tahirhassan.blogspot.com/2010/06/linq-to-sql-order-by-nulls-last.html, this Extension method works for LinqToSQL.

The custom tool ‘MSLinqToSQLGenerator’ failed. Unspecified error

Tim — Mon, 18 Jan 2010 08:29:15 +0000

I kept getting this error “The custom tool ‘MSLinqToSQLGenerator’ failed. Unspecified error. For me, this was caused when I was using partial classes and had several using statements at the top of the file:

using System.Data.Linq;
using System.Data.Linq.Mapping;
using System.Data;
using System.Collections.Generic;
using System.Reflection;
using System.Linq;
using System.Linq.Expressions;
using System.ComponentModel;
using System;

{namespace}

{code}

To get around this, I removed the using namespaces and ran the custom build tool, then readded the using statements which resolved my issue. This issue apparently is in SP1 VS2008!

References:

http://blog.unidev.com/index.php/2008/09/02/the-custom-tool-mslinqtosqlgenerator-failed-unspecified-error/

Serializing a Data Class (LINQ2SQL) for WCF

Tim — Sat, 12 Apr 2008 08:47:59 +0000

Problem

I created a class that implements a service contract interface so that I can return an array of data from a WCF service back to the client application.

The exposed method in the class return’s an array of Data Classes (an array of records from a database table) generated by the MSLINQ2SQL generator.

When generating the client code from the WCF service, an exception was raised stating
That the class could not be serialized.

Service cannot be started. System.Runtime.Serialization.InvalidDataContractException: Type ‘TDC_LIB.OM.TMPPlan’ cannot be serialized. Consider marking it with the DataContractAttribute attribute, and marking all of its members you want serialized with the DataMemberAttribute attribute.
at System.Runtime.Serialization.DataContract.DataContractCriticalHelper.ThrowInvalidDataContractException(String message, Type type)
at System.Runtime.Serialization.DataContract.DataContractCriticalHelper.CreateDataContract(Int32 id, RuntimeTypeHandle typeHandle, Type type)
at System.Runtime.Serialization.DataContract.DataContractCriticalHelper.GetDataContractSkipValidation(Int32 id, RuntimeTypeHandle typeHandle, Type type)
at System.Runtime.Serialization.DataContract.GetDataContractSkipValidation(Int32 id, RuntimeTypeHandle typeHandle, Type type)
at System.Runtime.Serialization.DataContract.GetDataContract(RuntimeTypeHandle typeHandle, Type type, SerializationMode mode)
at System.Runtime.Serialization.DataContract.GetDataContr…

Solution
Make sure that your data context object has the property “Serialization Mode” set to Unidirectional. This will add DataContract/DataMember attributes to the associated fields in your data classes.