Hello Robert, You misunderstood my problem I guess.
Think of bora as a unique word, with id 1. there is a dictionary entry for bora bora with id 2 then the phrase components representing this association are not unique in word_id X dictionary_id (both are 1,2) only word_id and dictionary_id AND list index (position) meaning there can only be one word on the same position of a list. The real problem is that I want to make sure bora bora is entered only once in the dictionary. For those who like more examples, think of travel itineraries (which are a list of cities, say New York - London - Paris - Budapest) Cities are a table, Itineraries are another and there is a join model (Visits) which acts as a list. How do I make sure an itinerary is created only once? Thanks a million all Vik On Jan 7, 5:45 pm, Robert Walker <[email protected]> wrote: > tron wrote: > > class Word > > end > > > class PhraseComponent > > belongs_to :word > > belongs_to :dictionary_entry > > acts_as_list :scope => :dictionary_entry > > end > > > class DictionaryEntry > > has_many :phrase_components > > has_many :words, :through => :phrase_components > > end > > Well from the database side of thing that's easily solved by adding a > unique index across the two foreign keys in the join table. That would > definitely prevent duplicates in the join table. > > CREATE UNIQUE INDEX idx_word_dictionary_entry ON phrase_components > (word_id, dictionary_entry_id); > > From the Rails side you might be able to use something like the > following example: > > class TeacherSchedule < ActiveRecord::Base > validates_uniqueness_of :teacher_id, :scope => [:semester_id, > :class_id] > end > > Maybe (untested): > > class PhraseComponent < ActiveRecord::Base > validates_uniqueness_of :word_id, :scope => :dictionary_entry > validates_uniqueness_of :dictionary_entry_id, :scope => :word_id > end > > Note: This may be an expensive method for validating uniqueness! > > In any of the cases mentioned you'll still have issues related to > "Optimistic Concurrency > Control:"http://en.wikipedia.org/wiki/Optimistic_concurrency_control > > This section of the Rails documentation has a good explanation of these > issues and some options on how to solve > them:http://www.railsbrain.com/api/rails-2.2.2/doc/index.html?a=M001824&na... > > -- > Posted viahttp://www.ruby-forum.com/. --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Google Groups "Ruby on Rails: Talk" group. To post to this group, send email to [email protected] To unsubscribe from this group, send email to [email protected] For more options, visit this group at http://groups.google.com/group/rubyonrails-talk?hl=en -~----------~----~----~----~------~----~------~--~---
