I am new to rails. Having a blast. The query API though is giving me
some trouble. I’ve been zooming and doing a lot of stuff very quickly,
but this is the first time I have spent hours trying to figure it out.
It’s not like anything I’ve used before - regular SQL, or Hibernate,
or whatever.
The model I have is pretty simple.
A PrivateMessage has many Recipients
A Recipient has a Receiver (which of class User)
- recipient also has fields for ‘is_read’ and ‘is_deleted’
My goal is to build a query that finds all the unread and not deleted
private messages for a given user. To accomplish this, we need to join
‘private_messages’ to ‘recipients’… and then ‘recipients’ to
‘users’.
My Recipient model has the following relevant code:
belongs_to :receiver, :class_name => ‘User’, :foreign_key =>
“receiver_id”
belongs_to :private_message
scope :unread, where(:is_read => false).where(:is_deleted => false)
scope :unread_by_receiver_id, lambda { |id|
unread.joins(:receiver).merge(User.by_id(id)) }
When tested in isolation, this works 100%.
However, when I code the private message queries, I run into problems.
belongs_to :sender, :class_name => ‘User’
has_many :recipients, :class_name => ‘Recipient’
scope :sorted, order(“private_messages.created_at desc”)
scope :newest, sorted.limit(3)
scope :newest_unread_by_user_id, lambda {
|id|
newest.joins(:recipients).merge(Recipient.unread_by_receiver_id(id)) }
When I try and use 'newest_unread_by_user_id, I get the following
exception:
ActiveRecord::ConfigurationError: Association named 'user' was not
found; perhaps you misspelled it?
This doesn’t make much sense to me… because if the name was spelled
wrong, why doesn’t it fail when I test it isolation?
Can someone help me out please? This one is driving me nuts. At times
like this, I just want to program in full sql and be done with it 
Thanks