Infinite loop during Rails model method - ruby-on-rails

Question

The Use Case
If users haven't filled their box with products up to their credit limit (6 by default), a method is called on the box model which fills it for them.
Code guide
The number of credits in the box is given by box_credits, which loops through all products in the box and returns the total value of them. This seems to work.
The boolean method box_filled? checks if the box_credits method is equal to or greater than the number of credits available (the subscription credits).
The fill_once method should add products to the box until the box is filled (box_filled? returns true). This will happen when box_credits equals the number of credits available.
The Code
def fill_once
unless self.box_filled?
# Get a random product from the user's recommendations
product = self.subscription.user.recommended_product_records[rand(self.subscription.user.recommended_product_records.length - 1)]
# Make sure the product hasn't already been included in the box
unless self.added_product_ids.include? product.id
# If fresh, add the product to the box, size-dependently
unless product.sample_price_credits.nil?
product.add_to_box_credits(self.subscription, "sample")
else
unless product.full_price_credits.nil?
product.add_to_box_credits(self.subscription, "full")
end
end
self.save!
end
self.fill_once # Here's the recursion
end
end
The box_filled? method looks like this:
def box_filled?
subscription = self.subscription
if self.box_credits >= subscription.credits
return true
else
return false
end
end
box_credits are determined by this method:
def box_credits
count = 0
unless self.added_product_hashes.nil?
# Takes product hashes in the form {id, size, method}
self.added_product_hashes.each do |product_hash|
# Add credits to the count accordingly
if product_hash["method"] == "credits"
# Depending on the product size, add the corresponding amount of credits
if product_hash["size"] == "sample"
# Get the credit cost for a product sample
cost = Product.find(product_hash["id"].to_i).sample_price_credits
count += cost
elsif product_hash["size"] == "full"
# Get the credit cost for a full product
cost = Product.find(product_hash["id"].to_i).full_price_credits
count += cost
else
next
end
else
next
end
end
end
return count
end
The Problem
fill_once runs forever: it seems to ignore the unless self.box_filled? conditional.
Attempted solutions
I tried removing the recursive call to fill_once from the fill_once method, and split it into an until loop (until box_filled? ... fill_once ...), but no joy.
Update
Multiple identical products are being added, too. I believe the issue is that the updated record isn't being operated on – only the original instance. E.g. unless self.added_product_ids.include? product.id checks against the original box instance, not the updated record, sees no products in the added_product_ids, and chucks in every product it finds.
Solution
OK, this is solved. As suspected, the updated record wasn't being passed into the iterator. Here's how I solved it:
# Add one random user recommended product to the box
def fill_once(box=self)
unless box.box_filled?
# Get a random product from the user's recommendations
product = box.subscription.user.recommended_product_records[rand(box.subscription.user.recommended_product_records.length - 1)]
# Make sure the product hasn't already been included in the box
unless box.added_product_ids.include? product.id
# If fresh, add the product to the box, size-dependently
unless product.sample_price_credits.nil?
box = product.add_to_box_credits(box.subscription, "sample")
else
unless product.full_price_credits.nil?
box = product.add_to_box_credits(box.subscription, "full")
end
end
end
fill_once(box)
end
end
Using Ruby's default arguments with a default of self, but the option to use the updated record instead, allows me to pass the record through the flow as many times as needed.

Answer 1

unless self.added_product_ids.include? product.id means no duplicate product will be add to box. So if all products recommend is add to box but the total credits is less than box_credits , may cause infinite loop. I'm not sure, but it could be the reason.
You could add
puts "Box credits #{self.box_credits} vs. credits: #{self.subscription.credits} "
before
self.fill_once # Here's the recursion
to see if this happens.

Answer 2

Solution
OK, this is solved. As suspected, the updated record wasn't being passed into the iterator. Here's how I solved it:
# Add one random user recommended product to the box
def fill_once(box=self)
unless box.box_filled?
# Get a random product from the user's recommendations
product = box.subscription.user.recommended_product_records[rand(box.subscription.user.recommended_product_records.length - 1)]
# Make sure the product hasn't already been included in the box
unless box.added_product_ids.include? product.id
# If fresh, add the product to the box, size-dependently
unless product.sample_price_credits.nil?
box = product.add_to_box_credits(box.subscription, "sample")
else
unless product.full_price_credits.nil?
box = product.add_to_box_credits(box.subscription, "full")
end
end
end
fill_once(box)
end
end
Using Ruby's default arguments with a default of self, but the option to use the updated record instead, allows me to pass the record through the flow as many times as needed.