How avoid concurrency belongs_to and has_many association?

rubyonrails-talk
1

How do I avoid concurrency and keep the data integrity if one user submit a form before the other?

My issue is that the last user to submit the person/_form.rb will get all chosen cards, same the cards that first user chose and I want to prohibit that.

    # person.rb
    class Person < ActiveRecord::Base
      has_many :cards
    end

    # card.rb
    class Card < ActiveRecord::Base
      belongs_to :person
      scope :not_assigned_to_a_person, -> { Card.where(person_id: nil    ) }
end

    # create_cards.rb
    create_table :cards do |column|
column.references :person, index: true
    end

    # person/_form.rb
    = f.input :card_ids        ,
collection: Card        .not_assigned_to_a_person,
label_method: :name, value_method: :id        ,
input_html: { multiple: true }

StackOverflow: http://stackoverflow.com/questions/25216219/how-do-i-avoid-concurrency-belongs-to-and-has-many-association

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2

How do I avoid concurrency and keep the data integrity if one user submit a form before the other?

My issue is that the last user to submit the person/_form.rb will get all chosen cards, same the cards that first user chose and I want to prohibit that.

    # person.rb

class Person < ActiveRecord::Base

      has_many :cards

end

# card.rb

class Card < ActiveRecord::Base

      belongs_to :person

      scope :not_assigned_to_a_person, -> { Card.where(person_id: nil ) }      end

# create_cards.rb

    create_table :cards do >column>       column.references :person, index: true

end

# person/_form.rb

    = f.input :card_ids ,          collection: Card .not_assigned_to_a_person,          label_method: :name, value_method: :id ,          input_html: { multiple: true }

StackOverflow: http://stackoverflow.com/questions/25216219/how-do-i-avoid-concurrency-belongs-to-and-has-many-association

Have a look back into the mists of time. This may still be useful.

Walter

3

Hi Walter,

I think that is not the case lock_version because my problem already exists on creation of two different Person which must includeCards (has_many) for these Person. My problem is: shouldn’t include Cards that have been associated.

I am not certainly, but I think the only way it is creating index or constrains on database tables.

Thanks,

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