referential integrity

rubyonrails-talk
1

I am starting out in rails and am loving it! Thanks to all the contributors!

I made a web app that had about 7 models, with some referring to each other, eg a team had a member and so on.

This relationship was not enforced in the model or in the database, it was kind of hacked together in the view by creating html select inputs.

I found very quickly that deleting models and adding new ones meant that objects that should not be related were.

I thought at first I should implement the correct cascading deletes. I have looked into this a little more and have now redefined all my models correctly, eg a team has_many :members.

I looked at the mysql database this created and there are no foreign key relationships.

question 1) should there be foreign key relations in mysql db? I used the script/generate model and then rake db:migrate

my model: class Developer < ActiveRecord::Base   belongs_to :team end

question 2) in my conceptual model my developer belongs to a team. So i have the model above. Should there be a relationship in team describing how the link exists to developer? Currently mine is empty: class Team < ActiveRecord::Base end

thanks in advanced for any help!

2

question 1) should there be foreign key relations in mysql db? I used the script/generate model and then rake db:migrate

Rails has no native support for foreign key constraints in the DB. I use the RedHillOnRails Core plugin, unfortunately there main site went offline not long ago but you can get the plugin from: http://github.com/harukizaemon/redhillonrails_core/tree/master. This allows you to specify foreign keys in migrations if you want the database to maintain referential integrity for you (dunno who wouldn't!).

question 2) in my conceptual model my developer belongs to a team. So i have the model above. Should there be a relationship in team describing how the link exists to developer? Currently mine is empty: class Team < ActiveRecord::Base end

You would say has_many :developers. The Rails API ActiveRecord::Associations documentation provides an in-depth discussion of relations.

Best regards, Andrew

3

Your Team has many members and should be noted:

class Team < ActiveRecord::Base     has_many :members end

This is assuming that you have a column in your member table named team_id. I think this is what you were asking about with the foreign keys.

As a somewhat noob to Rails myself I found a few good books for beginners to be the most help. The two I like the best are: "Simply Rails 2" and "Agile Web Development with Rails".