Rails has_many relationships when not saved (possibly ajax related) - ruby-on-rails

Question

Have a quick question about the has_many and belongs to. I'm in a situation where a :user has_many :accounts, and an :account belongs_to the user.
In my controller, I first assign #accounts = current_user.accounts. Debugging [correctly] reports to me that this particular use has 2 accounts. In the next line, I save an invalid account (debugging also tells me correctly that it is invalid). However, when I inspect current_user.accounts.count versus current_user.accounts.all.count versus current_user.accounts.all(order: 'created_at DESC'), I get the following values:
- current_user.accounts.count = 2
- current_user.accounts.all.count = 3
- current_user.accounts.all(order: 'created_at DESC') = 2
Inspection of the database confirms that the invalid model indeed did not get saved.
Furthermore, in my dynamically ajax re-loaded view to which I feed #accounts = current_user.accounts (which is set after the if-else loop checking if #account.save worked), it loops through and displays 3 accounts, including the invalid account.
Here's the code for the controller:
def create
#account = current_user.accounts.new(account_params)
if #account.save
#accounts = current_user.accounts.all(order: 'created_at DESC')
#redirect_to accounts_path, :success => "Account successfully created."
flash[:success] = "Account sucessfully created."
# respond_to :js
respond_to do |format|
format.js {
render :create
}
end
else
#accounts = current_user.accounts.all(order: 'created_at DESC')
flash[:error] = "There was a problem with adding your account."
respond_to do |format|
format.js {
render :create
}
end
end
puts "Final Accounts is #{#accounts.count} compared to #{current_user.accounts.all.count} compared to #{current_user.accounts.count}" # outputs 2, 3, and 2 for an invalid model being saved
end
Can someone explain to me the proper way I should be doing this? Or better yet, what is going on under the Rails engine? I feel sheepishly noob for having this issue.
How do I tell rails to only load the current_user.accounts that are saved in the db? Is this eager-loading related?
I'm running on Rails 4, with postgresql if this makes a difference.

Answer 1

The reason of confusion is a CollectionProxy in ActiveRecord::Associations (things are bit more complicated, than they looked):
current_user.accounts is a CollectionProxy, not an Array.
Think of CollectionProxy as of container, which internally has #owner as current_user, #target as set of accounts and #reflection - kinda links (associations) between #owner and #target
When you run current_user.accounts.new() - you just add another object into #target, so iterating over current_user.accounts you're iterating over #target, which contains objects including newly created.
But wait, why does .count return less objects?
Because Rails are lazy and #target is not loaded until you really need its objects(=accounts). So to just run .count it's cheaper to run direct SQL-request instead of instantiation of all objects in #target and then count 'em.
That's why when you do current_user.accounts.count you get amount of saved objects. And when you do current_user.accounts.all.count - it instantiate all objects in #target, convert 'em into Array and count accounts in this array (equal to current_user.accounts.size).
BTW, all is deprecated in Rails 4, use to_a instead
So, what do I do with all this knowledge, man? I just need to show accounts without unsaved one.
Just force reload: #accounts = current_user.accounts(force_reload = true)
OR #accounts = current_user.accounts.reload
OR #accounts = current_user.accounts.order('created_at DESC') It will run reload automagically because order needs direct request to objects via SQL