Question

I have no idea if this is possible … but it would be cool. the question is whether it is possible but then a bit of an example if possible.

I am not sure what method signature you would use to pass the lambda expression into.

Eg the method IList<Group> GetGroups()

How would you modify that to be able to pass a lambda expression into it?

The next question is how would you code a lambda expression to return all Group objects where for example

• where .deleted == false or
• where .DateAdded > aDate

Yeah, I want the moon on a stick 😉
Thanks in advance.

(edit I am thinking this is a bit ill-conceived actually because of the data access layer that would actually fetch the data … but assume that you are querying some object collection over the service and don’t have to worry about the dal).

Answer 1

You could declare the GetGroups method with a parameter of type Expression<Func<Group, bool>>, which represents a predicate that the group must match in order to be returned :

IList<Group> GetGroups(Expression<Func<Group, bool>> predicateExpression);

The trouble is, expressions can’t be serialized, so you couldn’t send it to the WCF service… However, you might find a way to do it with the Expression Tree Serialization project.