Adding many models to another model

Question

I'm currently working on a small project using Ruby On Rails 3.2 to create a database that contains several unique Models. Each Model has many Elements and each Element has the potential to belong to many Models. I have been able to set up the models in the following manner:

class Model < ActiveRecord::Base
  has_many :model_elements
  has_many :elements, :through => :model_elements
  attr_accessible :elements, :name, :notes, :ref
end

class Element < ActiveRecord::Base
  has_many :model_elements
  has_many :models, :through => :model_elements
  attr_accessible :elementType, :name, :notes, :ref
  validates_presence_of :name
end

class ModelElement < ActiveRecord::Base
  belongs_to :Model
  belongs_to :element
  attr_accessible :model_id, :created_at, :element_id
end

My question is how do I add multiple Elements to a single Model? I've tried to find some documentation but I can't find anything. Currently I'm trying to do the following:

@model.elements = @element

Where @element is a predefined element however it's throwing the following error:

undefined method `each' for #<Element:0x007ff803066500>

Any help would be greatly appreciated.

Amar · Accepted Answer · 2012-08-21 19:23:07Z

2

Try @model.elements << @element

answered Aug 21, 2012 at 19:23

Amar

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Comments

Kyle C · Accepted Answer · 2012-08-21 19:24:50Z

0

collection.create(attributes = {})

Returns a new object of the collection type that has been instantiated with attributes, linked to this object through the join table, and that has already been saved.

 @model.elements.create(:name => "example")

answered Aug 21, 2012 at 19:24

Kyle C

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Comments

Lukas Eklund · Accepted Answer · 2012-08-21 20:27:24Z

0

Amar's answer is correct. If you wanted you can simplify your models further by using the has_and_belongs_to_many association.

class Model < ActiveRecord::Base
  has_and_belongs_to_many :elements, :join_table => :model_elements
end

class Element < ActiveRecord::Base
  has_and_belongs_to_many :models, :join_table => :model_elements
end

@model.elements << @element

edited Aug 21, 2012 at 20:27

answered Aug 21, 2012 at 19:31

Lukas Eklund

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