Order matters!

As I’ve said before on this space, I’m a late adopter.  So some of my “realizations” are probably hashed out all over the web.  But I write most of this so that it burns in my memory. I’ve been working with LINQ on a new project.  I had a table come back with 55 unique records for product selection. The table contained, among other things, ProductCode, ProductDescription and linked to a table that contained a ProductSortOrder. What I wanted was a list sorted by the ProductSortOrder. The tables might look like:

• Code         Description
• ABC         Widget Shaft
• ABC         Widget Flange
• DEF         Whozit Shaft
• DEF         Whozit joint grease
• ZYX         Doodad ball
• ZYX         Doodad Clips

• Code          SortOrder
• ZYX               1
• ABC               2
• DEF               3

Initially, I did something like:

return   dataContext.Products.Distinct().OrderBy(x => x.ProductSort.SortOrder).Select(x => new  productKeys 
{
    value = x.Code,
    description = x.Description
}).ToList()

However, the list that this returned was sorted alphabetically, which was not the expected sort order. After some tinkering, I realized that I needed to place the OrderBy after the select, this would order my new productKeys objects in the list

return   dataContext.Products.Distinct().Select(x => new  productKeys
{
    Value = x.Code,
    Description = x.Description,
    Sort = x.ProductSort.SortOrder
}).OrderBy(x => x.Sort).ToList()

Now the list that is passed back takes the order:

ZYX ABC DEF