I'm a beginner to both Ruby and Rails and I'm currently reading the Agile
development with Rails, in which I'm currently developing the cart of the
store.
I have a *line_items* model which *belongs_to :products*. This makes sense.
Later in the example we use this code to check if a product is referenced
by any line items before we destroy it:
class Product < ActiveRecord::Base
has_many :line_items
before_destroy :ensure_not_referenced_by_any_line_item
private
# ensure that there are no line items referencing this product
def ensure_not_referenced_by_any_line_item
if line_items.empty?
return true
else
errors.add(:base, 'Line Items present')
return false
end
end
end
This makes sense to me except of one part: if line_items.empty? I can only
guess that *line_items *returns all the rows of the "line_items" table that
contain the product.id of the currently instantiated Product object, is that
right? But how does the model knows what to fetch just by "line_items"? Isn't
that too little info that we give to our model, regarding the logic of the task
it has to do? Don't we have to declare somewhere something like: *return false
if line_items.product.id == product.id* ?
Thanks in advance people!
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