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The has and belongs to many association

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A has_and_belongs_to_many association creates a direct many-to-many connection with another model, with no intervening model.

For example, if your application includes assemblies and parts, with each assembly having many parts and each part appearing in many assemblies, you could declare the models this way: 

class Assembly < ApplicationRecord
  has_and_belongs_to_many :parts
end
class Part < ApplicationRecord
  has_and_belongs_to_many :assemblies
end
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ActiveRecord Associations:
* ActiveRecord Associations
* Polymorphic association
* belongs to
* Self-Referential Association
* has many
* has one
* The has many through association
* The has one through association
* The has and belongs to many association
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66 Integrating React.js with Rails using Hyperloop
67 Change a default Rails application environment
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71 Payment features in Rails
72 Rails on docker
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