On Friday, March 30, 2012 5:53:06 AM UTC-7, Gruffalo wrote:
>
> Hello everyone!
>
>
> I've looked at the Sequel docs (Associations and Advanced Associations)
> and also at other assorted sources of help on the web but this problem
> eludes me.
>
>
> I'm trying to model the following situation in a standalone Ruby
> application using Sequel (both are new to me) –
>
>
> There are *customers*, who receive *services*. There are various fields
> associated with the *service provision*, like actual and estimated costs
> and so on. It makes sense to join the *customers *and *services* tables
> through *service_provisions* and to keep these values in the
> service_provisions table.
>
>
> My problem is that I would like to access the 'complete' service provision
> information from one of my models easily, that is the one that includes
> information from both the *services* and *service_provisions* tables.
>
>
> For example I currently have:
>
>
> Customer.first.services.first
>
> => #<Service @values={:id=>4, :service_id=>"window_cleaning",
> :service_name=>"Communal Window Cleaning", :display_order=>400,
> :category=>"block", :current=>true}>
>
>
> Customer.first.service_provisions.first
>
> #<ServiceProvision @values={:id=>2, :customer_id=>1, :service_id=>4,
> :actual=>10.0, :last_year_estimate=>9.0, :estimate=>11.0}>
>
>
> And I don't know how to set it up so I could do something like
>
> Customer.first.service_provisions.first.service_name
>
> Customer.first.service_provisions.first.last_year_estimate
>
>
> or
>
>
> Customer.first.services.first.service_name
>
> Customer.first.services.first.last_year_estimate
>
>
> whichever makes more sense (I like the …provision option more).
>
>
> It is as if I want to join the *Service* and *Service Provision *data
> together in some way?
>
>
>
> My models are:
>
>
>
> class Customer < Sequel::Model
>
> one_to_many :service_provisions
>
many_to_many :services, :join_table => :service_provisions
>
Your issue is that many_to_many by default does not select columns from the
join table. You can do so manually via the :select option:
many_to_many :services, :join_table => :service_provisions,
:select=>[:services_provisions.*, :services.*]
That will allow you to do:
Customer.first.services.first[:service_name]
Note that you need to use .[:column] instead of .column for columns in the
join table, since methods are only created for columns in the model's
table. You can do:
class Service
def_column_accessor :service_name
end
To create such methods manually, so that you can use .column.
Thanks,
Jeremy
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