RavenDB Static Index field with Max() aggregation

Question

My documents have a "Comments" collection, and I'd like to index the "Last Commented Date". I have statically defined index already working for other fields, so there's nothing wrong with my index. But attempting to add this new field is not working. I simply cannot ever get any results when searching by it.

I've tried getting the max date with a Max() aggregation (note that I have to handle cases where there are no comments)

testlastcommented = doc.Comments.Count > 0 ? doc.Comments.Select(c => c.DateEntered).Max() : null

This complains that DynamicList does not support Max(). I could swear that I had an iteration of this using Max() that worked, but now I can't get that working. But regardless even when it wasn't throwing an error, I wasn't able to query on the field.

So then I tried by OrderByDescending/FirstOrDefault as an alternative to Max()

testlastcommented = doc.Comments.OrderByDescending(c => c.DateEntered).FirstOrDefault()

This indexes with no errors. But whatever I do, it's as if the field doesn't exist in the index. I can't get any results with known values.

I broke down and added a calculated "LastCommented" property to the document and indexed that. That obviously works, but I'd rather not have to store a calculated field in the document.

Matt Johnson-Pint · Accepted Answer · 2014-04-11T18:18:46.570

2

Try this:

testlastcommented = doc.Comments.Select(c => c.DateEntered)
                                .OrderByDescending(x => x)
                                .FirstOrDefault()

edited Apr 11 '14 at 18:18

answered Apr 11 '14 at 18:03

Matt Johnson-Pint

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Nope, index errors: no overload for "OrderByDescending" takes 0 arguments. – InfinitiesLoop Apr 11 '14 at 18:16
What version of RavenDB are you running? – Matt Johnson-Pint Apr 11 '14 at 18:16
Here we go... this works! But why??? doc.Comments.Select(c => c.DateEntered).OrderByDescending(c => c).FirstOrDefault() – InfinitiesLoop Apr 11 '14 at 18:18
I see now why my firstordefault wasnt working, nevermind :) But why is Max() not supported? – InfinitiesLoop Apr 11 '14 at 18:20
If you're taking the max of a value that's in a collection in the same doc, then you're right - it *should* work. I think it's just a bug. What version are you running? – Matt Johnson-Pint Apr 11 '14 at 18:21
You might also try `.Select(c => c.DateEntered).Cast().Max()` - but I don't think you should *have* to do that. – Matt Johnson-Pint Apr 11 '14 at 18:22
1

I'll play with this more later and write up a bug report for H.R. – Matt Johnson-Pint Apr 11 '14 at 18:23

RavenDB Static Index field with Max() aggregation

1 Answers1