在Rails中将数组保存到postgres会引发ArgumentError：参数数量错误（3表示2）

Question

Using Rails 4.0.1 with postgres I have an activerecord column stored as an array

create_table "accounts", force: true do |t|
  t.string "schedule_days", default: [], array: true
end

I can assign an array just fine.

agent.schedule_days = agent.schedule_days << 1
 => [1] 

But the save does not persist.

agent = Account.last
agent.save
BEGIN
COMMIT

Some of the forums suggested that the ActiveRecord needs the column to be dirtied so:

agent.schedule_days_will_change!
 => [1] 

This causes the SQL statement to change but it raises an ArgumentError.

agent.save
(0.3ms)  BEGIN
SQL (0.9ms)  UPDATE "accounts" SET "schedule_days" = $1, "updated_at" = $2 
WHERE "accounts"."type" IN ('Ghost') AND "accounts"."id" = 6543  
[["schedule_days", [1]], ["updated_at", Wed, 27 Nov 2013 03:56:14 UTC +00:00]]
ArgumentError: wrong number of arguments (3 for 2): UPDATE "accounts" SET "schedule_days" = $1, "updated_at" = $2 WHERE "accounts"."type" IN ('Ghost') AND "accounts"."id" = 6543
(0.3ms)  ROLLBACK 
ArgumentError: wrong number of arguments (3 for 2)

Answer 1

This is because the activerecord-postgis-adapter is begin used rather than the default postgresql adapter provided by Rails. There may be an updated version of the activerecord-postgis-adapter that supports arrays.