I have a method to build an expression for a linq query for a given type, property, and value. This works wonderfully as long as the property on the type is NOT nullable. Here is the example I am working from (http://www.marcuswhitworth.com/2009/12/dynamic-linq-with-expression-trees) I am calling the Equals method on the property. However I have discovered that the Equals method for Nullable types takes an Object as a parameter instead of the Nullable type. I attempted to use GetValueOrDefault to hide the null values but EF doesn't support that method. As a simple example the following code will throw an error:
decimal? testVal = new decimal?(2100); var test = (from i in context.Leases where i.AnnualRental.Equals(testVal) select i).ToList();
However if you use == instead of the Equals() method it will work OK. I am not sure how to convert the code to use == instead of Equals() however. Any suggestions will be greatly appreciated.
If you say
==, you generate a
BinaryExpression with NodeType as
If you say
.Equals(x), you generate a
MethodCallExpressions that LinqToEntities may translate into Sql is a limitted list (for example none of your own undecorated methods are in that list).
Nullable<T>.Equals(x) is apparently not on that list.
.Equals(x) to LinqToEntities.