ActiveRecord left outer join with and clause - sql

Question

I am using Rails 3 with ActiveRecord and I cannot get it to generate the query I want without inserting almost plain SQL in it.
I simply want to execute this SQL query (actually the query is a little more complex but it's really this part that I cannot get right).
SELECT DISTINCT users.*, possible_dates.*
FROM users
LEFT OUTER JOIN possible_dates
ON possible_dates.user_id = users.id
AND possible_dates.event_id = MY_EVENT_ID;
which I managed to using
User.includes(:possible_dates)
.joins("LEFT OUTER JOIN possible_dates
ON possible_dates.user_id = users.id
AND possible_dates.event_id = #{ActiveRecord::Base.sanitize(self.id)}"
)
.uniq
but I feel that I am missing something to simply add the AND condition of the left join using ActiveRecord query methods.
I also tried to do something like this
User.includes(:possible_dates)
.where('possible_dates.event_id' => self.id)
.uniq
but this yields (as expected), a query with a WHERE clause at the end and not the AND clause I want on the join.
By the way, self in the two snippets above is an instance of my Event class.
Thank you for your help.

Answer 1

(1 year later...)
After looking around, I found out that the best was probably to use arel tables.
For the above example, the following code would work.
ut = User.arel_table
pt = PossibleDate.arel_table
et = Event.arel_table
User.joins(
ut.join(pt, Arel::Nodes::OuterJoin)
.on(pt[:user_id].eq(u[:id])
.and(pt[:event_id].eq(1))
).join_sql
).includes(:possible_dates).uniq
the 1 in eq(1) should be replaced by the correct event id.