On Sep 27, 2:42 pm, Magnus <[email protected]> wrote:
> I have a database where information that should really have been a
> proper one-to-many relation is stored in a string. I would like to
> create a model that looks like a proper one-to-many relation and hides
> the ugly implementation details.
>
> Assuming I have a table with two columns: [UserID] and [Contacts],
> where Contacts is a string that contains multiple contacts encoded as
> a single string. Each contact has a name and a phone number. (E.g. the
> contacts string may look something like "John:555-000-9998;Tony:
> 333-222-1111;Mia:444-333-1122").
>
> I would like to create a User model that has a one-to-many relation to
> a Contact model, which has Name and Phone fields. What methods do I
> need define/override to accomplish this?
Maybe something like:
class Contact
attr_accessor :name, :phone
def initialize(name, phone)
self.name, self.phone = name, phone
end
def to_user_string
"#{name}:#{phone}"
end
end
class User
def contacts
@contacts ||= super.split(';').map{|s| s = s.split(':');
Contact.new(:name=>s[0], :phone=>s[1])}
end
def add_contact(name, phone)
contacts << Contact.new(:name=>name, :phone=>phone)
end
def before_save
self[:contacts] = @contacts.map{|c| c.to_user_string}.join(';') if
@contacts
super
end
end
You could also look at the composition plugin (http://
sequel.rubyforge.org/rdoc-plugins/classes/Sequel/Plugins/
Composition.html), but that's more for storing a single object in a
row than multiple objects.
Jeremy
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