Rails - Apr 2006 - Write/Display AR query as Grouped Results?

I''ve got a publications table that contains an author_id foreign key
and
a pubrole_id foreign key. What I want to do is query the DB using AR so
that I can get a list of all publications that belong_to a particular
author, and group the results by the pubrole.role_name (Author, Joint
Author, Editor, etc.) so that the results look something like:

Author
  book1 info
  book2 info
  etc.

Joint Author
  book1 info
  book2 info

Editor

etc.

Can anyone suggest how to do this, or point to an example that already
exists?

Thanks.

-- 
Posted via http://www.ruby-forum.com/.

chris wrote:
> I''ve got a publications table that contains an author_id foreign
key and
> a pubrole_id foreign key. What I want to do is query the DB using AR so
> that I can get a list of all publications that belong_to a particular
> author, and group the results by the pubrole.role_name (Author, Joint
> Author, Editor, etc.) so that the results look something like:
> 
> Author
>   book1 info
>   book2 info
>   etc.
> 
> Joint Author
>   book1 info
>   book2 info
> 
> Editor
You can construct the sql clause with "find_by_sql":

@publications = Publication.find_by_sql ["select p.*, r.role_name from 
publications p, pubroles r where p.author_id = ? and p.pubrole_id = r.id 
group by r.role_name, p.book_name", author_id]

...or something like that. :)

Jeff

-- 
Posted via http://www.ruby-forum.com/.

chris wrote:
> I''ve got a publications table that contains an author_id foreign
key and
> a pubrole_id foreign key. What I want to do is query the DB using AR so
> that I can get a list of all publications that belong_to a particular
> author, and group the results by the pubrole.role_name (Author, Joint
> Author, Editor, etc.) so that the results look something like:
> 
> Author
>   book1 info
>   book2 info
>   etc.
> 
> Joint Author
>   book1 info
>   book2 info
> 
> Editor
> 
> etc.
> 
> Can anyone suggest how to do this, or point to an example that already
> exists?
> 
> Thanks.
Try using the new group_by function.  It works great.  you should be 
able to do it using something like the following:

CONTROLLER:
@publications = Publication.find :all, :conditions => [''author_id =
?'',
@author.id]

VIEW:
<% @publications.group_by{|p| p.pubrole.role_name }.each do |role_name, 
publications| %>


<h2><%= role_name %></h2>

    <% for pub in publications %>
        . . .
    <% end %>

<% end %>

-- 
Posted via http://www.ruby-forum.com/.

Steve

Is that new for 1.1? Very cool. Any documentation on it? I looked at
api.rubyonrails.com but didnt see it listed there.



-- 
Posted via http://www.ruby-forum.com/.

Hi Chris,
> Is that new for 1.1? Very cool. Any documentation on it? I looked at
> api.rubyonrails.com but didnt see it listed there.
See  :
http://weblog.rubyonrails.org/articles/2006/03/01/new-in-rails-enumerable-group_by-and-array-in_groups_of

and r3726.

    -- Jean-Fran?ois.


--
? la renverse.

Jean-Fran?ois wrote:
> Hi Chris,
>> Is that new for 1.1? Very cool. Any documentation on it? I looked at
>> api.rubyonrails.com but didnt see it listed there.
> 
> See  :
>
http://weblog.rubyonrails.org/articles/2006/03/01/new-in-rails-enumerable-group_by-and-array-in_groups_of
> 
> and r3726.
> 
>     -- Jean-Fran?ois.
I noticed that too, but I am also curious about where is the actual 
documetation for it?  What module contains groups_by, and is there a 
proper RDoc for it?

Jeff

-- 
Posted via http://www.ruby-forum.com/.

Hello Jeff,
> Jean-Fran?ois wrote:
> > Hi Chris,
> >> Is that new for 1.1? Very cool. Any documentation on it? I looked
at
> >> api.rubyonrails.com but didnt see it listed there.
> >
> > See  :
> >
http://weblog.rubyonrails.org/articles/2006/03/01/new-in-rails-enumerable-group_by-and-array-in_groups_of
> >
> > and r3726.
> >
> I noticed that too, but I am also curious about where is the actual
> documetation for it?
You''re right, there isn''t :)
> What module contains groups_by, and is there a
> proper RDoc for it?
It''s an add-on for the module Enumerable so it''s in
ActiveSupport, in
activesupport-xx/lib/active_support/core_ext/enumerable.rb

and you will see in the first line of the file :

module Enumerable #:nodoc:

The news or the source are the documentation.

    -- Jean-Fran?ois.


--
? la renverse.