Failry simple(?) active record question

ruby-talk
1

I'm plodding my way through active record right now, and running into
some things that seem odd.

Take a really simple example
#!/usr/bin/ruby
require 'rubygems'
require 'active_record'

ActiveRecord::Base.establish_connection(:adapter => "sqlite3",
:database => "foo.db")

ActiveRecord::Schema.define() do
  create_table :containers do |table|
    table.column :name, :string
  end
  create_table :things do |table|
    table.column :description, :string
  end
end

class Container<ActiveRecord::Base
  has_many :things
end

class Thing<ActiveRecord::Base
  belongs_to :container
end

Container.create(:name=>"Bucket")
bucket=Container.find_by_name("Bucket")
pocket=Container.create(:name=>"Pocket")

bucket.save
pocket.save

Container.find(:all)
#this will find both containers

Thing.find(:all)
#empty, as expected

bucket.things.create(:description=>"fish")
pocket.things.create(:description=>"lint")

Thing.find(:all)
#looks good...

#but howcome
pocket.things.find(:all)
#throws some huge error instead of finding the things in the pocket?

Sorry for the overly newbie type question :slight_smile: I just really thought
ActiveRecord was supposed to take care of all this stuff.

Thanks,
           Kyle

2

What error do you get? That would help in diagnosing the problem.

You might also want to ask the Ruby on Rails list. I know ActiveRecord
doesn't have to be used with Rails, but they probably have more people
there with ActiveRecord experience.

Jeremy

···

On Nov 26, 9:32 pm, Kyle Schmitt <kyleaschm...@gmail.com> wrote:

I'm plodding my way through active record right now, and running into
some things that seem odd.

Take a really simple example
#!/usr/bin/ruby
require 'rubygems'
require 'active_record'

ActiveRecord::Base.establish_connection(:adapter => "sqlite3",
:database => "foo.db")

ActiveRecord::Schema.define() do
  create_table :containers do |table|
    table.column :name, :string
  end
  create_table :things do |table|
    table.column :description, :string
  end
end

class Container<ActiveRecord::Base
  has_many :things
end

class Thing<ActiveRecord::Base
  belongs_to :container
end

Container.create(:name=>"Bucket")
bucket=Container.find_by_name("Bucket")
pocket=Container.create(:name=>"Pocket")

bucket.save
pocket.save

Container.find(:all)
#this will find both containers

Thing.find(:all)
#empty, as expected

bucket.things.create(:description=>"fish")
pocket.things.create(:description=>"lint")

Thing.find(:all)
#looks good...

#but howcome
pocket.things.find(:all)
#throws some huge error instead of finding the things in the pocket?

Sorry for the overly newbie type question :slight_smile: I just really thought
ActiveRecord was supposed to take care of all this stuff.

Thanks,
           Kyle

3

AR questions should go to the rails list... that's the group that writes and supports AR.

···

On Nov 26, 2007, at 19:32 , Kyle Schmitt wrote:

I'm plodding my way through active record right now, and running into
some things that seem odd.

4

Kyle Schmitt wrote:

Take a really simple example

ActiveRecord::Schema.define() do
  create_table :containers do |table|
    table.column :name, :string
  end
  create_table :things do |table|
    table.column :description, :string
  end
end
..
#but howcome
pocket.things.find(:all)
#throws some huge error instead of finding the things in the pocket?

Kyle,

   when you have a relationship 'belongs_to', you need to define a field
in the database table to references the parent (the name is
<parent_singular>_id), as ActiveRecord does not create this field
automatically. So, we just need a 'container_id' in the 'things' table:

ActiveRecord::Schema.define() do
  create_table :containers do |table|
    table.column :name, :string
  end

  create_table :things do |table|
    table.column :description, :string
    table.column :container_id, :integer # <-- here
  end
end

Your example runs now fine.
You could also add an index (with 'add_index') for performance.

Regards

Raul

···

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5

OK. I'll repost it there. As I really wanna just use AR and not
rails :wink: I had hopes for this list.

Heck maybe this just means if I'm having this much trouble I should
write all my findings up as a few good examples and howto's.

Thanks
          --Kyle