How to specify conditions on joined tables in rails - sql

Question

I am trying to do a query in in Rails with ActiveRecord that specifies some condition on a joined table. And i can't seem to get it to work, even though i follow the examples from here:
http://guides.rubyonrails.org/active_record_querying.html#specifying-conditions-on-the-joined-tables
From the guides:
Client.joins(:orders).where(:orders => {:created_at => time_range})
My database schema looks like this, with tables scores, submissions and tasks:
create_table "scores", :force => true do |t|
t.integer "value"
t.integer "user_id"
t.datetime "created_at"
t.datetime "updated_at"
end
add_index "scores", ["user_id"], :name => "index_scores_on_user_id"
create_table "submissions", :force => true do |t|
t.integer "user_id"
t.integer "task_id"
t.integer "score_id"
t.datetime "completed_at"
t.datetime "created_at"
t.datetime "updated_at"
end
add_index "submissions", ["score_id"], :name => "index_submissions_on_score_id"
add_index "submissions", ["task_id"], :name => "index_submissions_on_task_id"
add_index "submissions", ["user_id"], :name => "index_submissions_on_user_id"
create_table "tasks", :force => true do |t|
t.integer "episode_id"
t.integer "score"
t.string "key"
t.datetime "created_at"
t.datetime "updated_at"
end
So i want to do a query where I can find all "scores" that have a relation to a spesific task. Submission belongs to tasks and scores.
My query now looks like this:
Score.joins(:submission).where(:submission => {:task_id => 1})
This generates the following syntax:
SELECT "scores".* FROM "scores" INNER JOIN "submissions" ON "submissions"."score_id" = "scores"."id" WHERE "submission"."task_id" = 1
Which generates the following error:
SQLite3::SQLException: no such column: submission.task_id
But there is a column submission.task_id, which you can see in the db schema. And i can do this successfully:
SELECT "submissions".* FROM "submissions" WHERE "submissions"."task_id" = 1

Answer 1

The name in the clause should be plural to reference the table name:
Score.joins(:submission).where(:submissions => {:task_id => 1})

Answer 2

I find this to be easier.
Score.joins(:submission).merge(Submission.where(task_id: 1))

Answer 3

The clause name should be plural to reference the table name.
Score.joins(:submission).where(submissions: { task_id: 1 })
If score has many submissions, the joins symbol should also be plural to reference the relation between Score and Submission.
Score.joins(:submissions).where(submissions: { task_id: 1 })

Answer 4

A caveat: if you're using non-standard table names the above will fail like so:
ActiveRecord::StatementInvalid: PG::UndefinedTable: ERROR: missing FROM-clause entry for table "submissions"
To fix this, put (joined-model-class).table_name as a key in the where hash:
Score.joins(:submission).where(
Submission.table_name => {task_id: 1}
)