Rails 4 where clause on nested joined tables - ruby-on-rails

Question

currently I have this query:
Mother.joins(camp: [{ sub_center: [{ health_center: :block }] }])
which essentially joins the mother table to the block table through the camp, sub_center, and health_center tables (I know it's a lot to take). I want to be able to do something like this:
Mother.joins(camp: [{ sub_center: [{ health_center: :block }] }]).where(sub_center_id: 1)
However, I get that sub_center_id is an undefined column PG::UndefinedColumn: ERROR: column mothers.sub_center_id does not exist
How do I get it to query camp.sub_center_id instead of mother.sub_center_id? In other words, how do I execute a where clause on nested joined tables?
Here's the schema for given tables:
create_table "mothers", force: :cascade do |t|
t.integer "camp_id"
t.integer "eligible_couple_id"
t.string "pcts_id"
t.integer "thumb_id"
t.string "survey_id"
t.string "necklace_id"
t.integer "necklace_replacement_number", default: 0
t.boolean "facility_referral_true", default: false
t.float "weight_at_las_pnc"
t.integer "created_by"
t.integer "updated_by"
t.datetime "created_at", null: false
t.datetime "updated_at", null: false
t.string "reg_id"
t.string "nfc_data"
t.datetime "date_of_registration"
t.integer "status", default: 1, null: false
t.datetime "deleted_at"
t.datetime "completed_at"
end
create_table "camps", force: :cascade do |t|
t.string "english_name"
t.string "local_name"
t.float "latitude"
t.float "longitude"
t.datetime "created_at"
t.datetime "updated_at"
t.integer "created_by"
t.integer "updated_by"
t.integer "sub_center_id"
t.integer "week_of_the_month"
t.integer "status", default: 1
t.integer "day"
t.datetime "deleted_at"
end
create_table "health_centers", force: :cascade do |t|
t.integer "block_id"
t.string "english_name"
t.string "local_name"
t.boolean "phc_true", default: false
t.boolean "ipd_true", default: false
t.boolean "fru_true", default: false
t.boolean "always_open_true", default: false
t.string "phone_number"
t.integer "created_by"
t.integer "updated_by"
t.datetime "created_at", null: false
t.datetime "updated_at", null: false
t.integer "status", default: 1
t.datetime "deleted_at"
end
create_table "sub_centers", force: :cascade do |t|
t.integer "health_center_id"
t.string "english_name"
t.string "local_name"
t.boolean "phc_true", default: false
t.boolean "ipd_true", default: false
t.boolean "fru_true", default: false
t.boolean "always_open_true", default: false
t.string "phone_number"
t.float "latitude"
t.float "longitude"
t.integer "created_by"
t.integer "updated_by"
t.datetime "created_at", null: false
t.datetime "updated_at", null: false
t.integer "status", default: 1
t.datetime "deleted_at"
end
create_table "blocks", force: :cascade do |t|
t.string "english_name"
t.string "local_name"
t.datetime "created_at"
t.datetime "updated_at"
t.integer "created_by"
t.integer "updated_by"
t.integer "status", default: 1
t.datetime "deleted_at"
end

Answer 1

You can always use the string method to reference the column, instead of the symbol one.
Mother.
joins(camp: { sub_center: { health_center: :block } }).
where('camps.sub_center_id = ?', 1)
or with the symbol method
Mother.
joins(camp: { sub_center: { health_center: :block } }).
where(camps: { sub_center_id: 1 } )