In a previous question I asked how to make "Computed properties" in a linq to sql object. The answer supplied there was sufficient for that specific case but now I've hit a similar snag in another case.
I have a database with Items that have to pass through a number of Steps. I want to have a function in my database that retrieves the Current step of the item that I can then build on. For example:
var x = db.Items.Where(item => item.Steps.CurrentStep().Completed == null);
The code to get the current step is:
Steps.OrderByDescending(step => step.Created).First();
So I tried to add an extension method to the EntitySet<Step> that returned a single Step like so:
public static OrderFlowItemStep CurrentStep(this EntitySet<OrderFlowItemStep> steps)
{
return steps.OrderByDescending(o => o.Created).First();
}
But when I try to execute the query at the top I get an error saying that the CurrentStep() function has no translation to SQL. Is there a way to add this functionality to Linq-to-SQL in any way or do I have to manually write the query every time? I tried to write the entire query out first but it's very long and if I ever change the way to get the active step of an item I have to go over all the code again.
I'm guessing that the CurrentStep() method has to return a Linq expression of some kind but I'm stuck as to how to implement it.