Linq join - group by - OrderByDescending query

Question

I have this query:

from i in dc.TFFiles                    
where i.Tid == tid
group i by new { i.Title, i.Type } into gr
select gr.OrderByDescending(g => g.Version).First();

I want to add a join with another table so I will have access to a field of the second table

Here is the join I need without the group by:

from i in dc.TFFiles
join c in dc.FCategory on i.CatId equals c.id 
....

How I can combine the group by query with the join

Tried like this but it doesn't order the results by Version descending. I always get Version 1 even though there are files with higher versions.

var result =
                    from i in dc.TFFiles                    
                    where i.Tid == tid                    
                    group i by new { i.Title, i.Type } into gr
                    orderby gr.FirstOrDefault().Version descending
                    join c in dc.FCategories on gr.FirstOrDefault().CatId equals c.Id
                    select new { id = gr.FirstOrDefault().id, Title = gr.FirstOrDefault().Title, Version = gr.FirstOrDefault().Version };

https://stackoverflow.com/questions/9173410/linq-combining-join-and-group-by — Roman Marusyk, Feb 09 '18 at 09:57
@MegaTron Tried that but couldn't make it work with the `select gr.OrderByDescending(g => g.Version).First();` — aggicd, Feb 09 '18 at 09:58

score 1 · Accepted Answer · answered Feb 09 '18 at 12:49

Maybe you can try that :

var result =
                    from i in dc.TFFiles                    
                    where i.Tid == tid                    
                    group i by new { i.Title, i.Type } into gr
                    join c in dc.FCategories on gr.FirstOrDefault().CatId equals c.Id
                    select new { id = gr.FirstOrDefault().id, Title = gr.FirstOrDefault().Title, Version = (from cv in gr select cv.Version).Max() };

Linq join - group by - OrderByDescending query

1 Answers1