Rails 5.1: getting records for a nested link with included
I am trying to implement includes in has_many
/ associations belongs_to
similar to this example:
class Author < ApplicationRecord
has_many :books, -> { includes :line_items }
end
class Book < ApplicationRecord
belongs_to :author
has_many :line_items
end
class LineItem < ApplicationRecord
belongs_to :book
end
The moment I do @author.books
I can see that in my console it downloads Book
and LineItem
and shows records Book
, there are no records for LineItem
. I am getting undefined method error when trying @author.books.line_items
. Doesn't work @author.line_items
.
How do I get the LineItem
entries for Author
please? Thank!
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You need to add the association has_many
to Author
.
Example has_many :line_items, through: :books, source: :line_items
.
Then, if you follow through author.line_items
, you get the entries LineItem
for the author.
As you use the includes method , you can access it line_items
through the books. Something like this:, author.books.first.line_items
this code will not go to the database, because includes
you have it has_many :books, -> { includes :line_items }
automatically loadedline_items
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