Using Rails/AR to generate this complex query
In trying to solve a grouping and ordering problem (original question here: "Complex" grouping and indexing in rails?), I got a SQL query that will fetch the right records the right way.
My qu开发者_C百科estion now is: how do I generate this SQL query using Rails/AR synthax?
The SQL-query is as follows:
SELECT
u.id as owner_id, u.name as owner_name, t.id, t.due_date
FROM users u
INNER JOIN tasks m ON u.id = m.owner_id
INNER JOIN tasks t ON u.id = t.owner_id
GROUP BY u.id, u.name, t.id, t.due_date
ORDER BY MIN(m.due_date), t.due_date
I think you'll need to play around with your database and these attributes to get it just right, but you could try something like this.
class User < ActiveRecord::Base
has_one :next_task, :class_name => :task, :order => "due_date desc", :limit => 1
has_many :tasks, :order => "due_date desc"
end
class Task < ActiveRecord::Base
belongs_to :user
end
User.include([:next_task,:tasks]).order("task.due_date desc").tasks.each { |task|
puts task.user.owner_id
puts task.user.owner_name
puts task.due_date
}
I'm not sure about the order clause to sort the users... you'll have to inspect the SQL generated to determine exactly what needs to be there.
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