在关联Rails的多个记录中选择特定记录

Question

I have a model called User and associated model Message . So user can have many messages. I have 4 columns in messages table named sent_at , opened_at , clicked_at and email id .

In message table email id is not unique. User would have sent multiple emails. So for a user in messages table he can see same email multiple times.

eg: If user_id is 7 and I need to find out the recent opened emails using the association. I need the records of all the users who have opened the mail recently.

I used this:

User.find(7).messages.select(*).group(:email_id).having("max(opened_at)")

But its giving men the error.

Any help is largely appreciated!! Thanks in advance!!

Answer 1

I got the answer after doing lot of research

a = User.find(7).messages.order("opened_at,clicked_at”).group_by(&:email_id)

This will return hash. I will convert this to array using a.to_a and from there I can access the entire active record