Linq OrderBy an expression

[Andrew Davey]

Is it possible to have something like:

var query = session.Query<Thing>().Where(...);
var defaultDate = DateTime.UtcNow.AddDays(1);
query.OrderBy(x => x.Date.HasValue ? x.Date : defaultDate);

?

When executing, I get an exception:
Unable to cast object of type
'System.Linq.Expressions.FullConditionalExpression' to type
'System.Linq.Expressions.MemberExpression'

Is this a limitation of the linq api or the underlying system?

Can someone suggest an alternative approach please?

[Rob Ashton]

That would be quite challenging I think, unless we had *specific*
handling for this particular scenario (a hack)

[Ayende Rahien]

No, we can't handle that scenario.

[Ayende Rahien]

RavenDB doesn't allow any sort of computation in the indexing stage.

What you can do is emit the Date field in the index with whatever logic you have in it, which will allow you to get the same result.

[Andrew Davey]

How about adding support for null coalescing? e.g. detect calls to
Nullable<T>.GetValueOrDefault(someVar)
That would work for my use case.

[Andrew Davey]

I'm not very familiar with creating more complex indexes (I've been so
happy with the dynamic index magic!)
Could you give a brief example of what I need to do? Should I use an
AbstractIndexCreationTask<T> to do it?