Extending the LINQ provider

Sometimes you will need a more sophisticated way to translate method calls to HQL. In this recipe, we will show you how to implement a custom LINQ to HQL generator that is able to do this.

Getting ready

Complete the Using custom dialect functions recipe.

How to do it…

1. Create a new class library project named CustomLinqGenearatorExample.
2. Install the NHibernate and log4net packages using the NuGet Package Manager Console by executing the following command:

   Install-Package NHibernate
   Install-Package log4net
   

3. Create the DateTimeFunctionsGenerator class using the following code:

   public class DateTimeFunctionsGenerator
     : BaseHqlGeneratorForMethod
   {
     public DateTimeFunctionsGenerator()
     {
       SupportedMethods = new[]
       {
         ReflectionHelper.GetMethod<DateTime>(
           d => d.AddDays(0)),
         ReflectionHelper.GetMethod<DateTimeOffset>(
           d => d.AddDays(0)),
         ReflectionHelper.GetMethod<DateTime>(
           d => d.AddHours...