Sorting on a calculated column in a table-plus

[Mike]

Sorting on a calculated column in table-plus is quite annoying.  I have searched for answers - and I haven't been able to find one....has anyone else?

So here is my solution, not DRY, but it works.  It is based on the idea that someone suggested for creating a view - but I wanted to define it in the app itself.

 ---

In the model, where you have defined the variable like

def mycolumn

  one_column - two_column

end 

you can add a named_scope and inject sql like

named_scope :specialscope, {

:select => "mymodels.*, (mymodels.one_column - mymodels.two_column) as mycolumn"

  } 

and then in your controller you just add the named scope, and table-plus sorting options....

  def index 
    hobo_index Mymodel.specialscope.apply_scopes(:search    => [params[:search], :blah1, :blah2], :order_by  => parse_sort_param(:mycolumn, :name))
  end  

magic! it works!

 what do you guys think?  is this really bad for performance etc?  

[Gert Thiel]

My app includes myriads of calculated columns. I prefer SQL views that include these calculated columns so Rails / Hobo don't need to know about that detail.

[Bryan Larsen]

The other option is counter_cache and similar denormalizations.
That's the approach I usually use.

Bryan

> --
> You received this message because you are subscribed to the Google Groups
> "Hobo Users" group.
> To view this discussion on the web visit
> https://groups.google.com/d/msg/hobousers/-/EdNsvVYDslUJ.
>
> To post to this group, send email to hobo...@googlegroups.com.
> To unsubscribe from this group, send email to
> hobousers+...@googlegroups.com.
> For more options, visit this group at
> http://groups.google.com/group/hobousers?hl=en.