On Feb 19, 10:05 am, Simon Arnaud <[email protected]> wrote:
> Hi
>
> I may be missing something, but I can't find out how to create a
> subset with conditions on an associated model.
>
> Let's take a simple example, with people who owns shoes.
>
> ### subset.rb ###
> require 'sequel'
> require 'logger'
>
> DB = Sequel.sqlite
>
> DB.create_table! :people do
> primary_key :id
> String :name
> end
>
> DB.create_table! :shoes do
> primary_key :id
> String :color
> Integer :person_id
> end
>
> class Person < Sequel::Model
> one_to_many :shoes
> subset(:with_red_shoes) do |p|
> p.shoes.color == 'red'
> end
> end
>
> class Shoe < Sequel::Model
> many_to_one :person
> end
>
> p Person.with_red_shoes
>
> ### subset.rb ###
>
> $ ruby -rubygems -Ku subset.rb
> subset.rb:20: undefined method `color' for #<Sequel::SQL::Identifier:
> 0x7f8a4da07f88 @value=:shoes> (NoMethodError)
> from /var/lib/gems/1.8/gems/sequel-2.10.0/lib/sequel_core/dataset/
> sql.rb:803:in `call'
> from /var/lib/gems/1.8/gems/sequel-2.10.0/lib/sequel_core/dataset/
> sql.rb:803:in `filter_expr'
> from /var/lib/gems/1.8/gems/sequel-2.10.0/lib/sequel_core/dataset/
> sql.rb:180:in `filter'
> from /var/lib/gems/1.8/gems/sequel-2.10.0/lib/sequel_model/base.rb:
> 416:in `with_red_shoes'
> from /var/lib/gems/1.8/gems/sequel-2.10.0/lib/sequel_model/base.rb:
> 156:in `with_red_shoes'
> from subset.rb:28
>
> I've tried different strategies, but to no avail
> def_dataset_method
> def self.with_red_shoes
> one_to_many :with_red_shoes, :class => :Shoe, :graph_condition =>
> { :color => 'red' }
>
> Is there a way to do it ?
You almost had it. Because you are filtering based on criteria in an
associated table, you need to use eager_graph, and
the :graph_join_type has to be inner to exclude people that don't have
red shoes.
class Person < Sequel::Model
one_to_many :shoes
one_to_many :red_shoes, :class=>:Shoe, :graph_join_type=>:inner, :conditions=>
{:color=>'red'}
def_dataset_method(:with_red_shoes){eager_graph(:red_shoes)}
end
The above code requires the master branch, if you are using 2.10.0,
you need to change :conditions to :graph_conditions.
Jeremy
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