"Selecting" a calculated row / Using :select in the paginate

Rails
1

Hi,

I was trying to use the :select parameter to select a calculated row,
but it appears that the parameter is not picked up by the paginate
method.

I want to add the following to the select statement:

timediff(now(), created_on) as age

So I tried:

@story_pages, @stories = paginate :stories, {:per_page => 10, :include
=> ‘user’, :select => ‘timediff(now(), story.created_on) as story_age’}

… to no avail.

I know I can create a method named “age” for the story model that can
retrieve that calculation, but that’s a query for each element, so it’s
very undesirable.

In case you’re wondering why I don’t calculate the “age” inside my Rails
app, check this blog:

http://railsexpress.de/blog/articles/2005/11/09/accelerate-your-dates

If you know of a solution or alternative, I’ll greatly appreciate your
help.

Sincerely,
Ivan V.

2

Iván Vega R. wrote:

@story_pages, @stories = paginate :stories, {:per_page => 10, :include
=> ‘user’, :select => ‘timediff(now(), story.created_on) as story_age’}

… to no avail.

I’m somewhat sure that paginate (and find for that matter) don’t know
what to do with the :select option.

Try using find_by_sql()

3

Check out this code snippet:

Even better is the updated version in ‘toolmantim’s’ post at the bottom.

4

Check
http://railsexpress.de/blog/articles/2005/11/06/the-case-for-piggy-backed-attributes
:wink:

5

Thanks!