从Rails 2.3迁移到Rails 3.1时的活动记录错误

Question

I am migrating from a rails 2.3 application to Rails 3.1, i am getting this error when i try to save a record. This was not happening earlier and i am not sure what could be the reason, any help would be appreciated, Thanks.

Here are previews of my models

**

class Store < ActiveRecord::Base 
has_many :orders
end

**

**

class Order < ActiveRecord::Base 
has_many :items, :dependent => :delete_all
end

**

**

class Item < ActiveRecord::Base 
belongs_to :order
validates_presence_of :order_id
end

**

Below is error message log when i try to save

**

ActiveRecord::RecordInvalid: Validation failed: Items order can't be blank
    from /Users/branch/.rvm/gems/ruby-1.9.3-p484/gems/activerecord-3.1.12/lib/active_record/validations.rb:56:in `save!'
    from /Users/branch/.rvm/gems/ruby-1.9.3-p484/gems/activerecord-3.1.12/lib/active_record/attribute_methods/dirty.rb:33:in `save!'
    from /Users/branch/.rvm/gems/ruby-1.9.3-p484/gems/activerecord-3.1.12/lib/active_record/transactions.rb:246:in `block in save!'
    from /Users/branch/.rvm/gems/ruby-1.9.3-p484/gems/activerecord-3.1.12/lib/active_record/transactions.rb:295:in `block in with_transaction_returning_status'
    from /Users/branch/.rvm/gems/ruby-1.9.3-p484/gems/activerecord-3.1.12/lib/active_record/connection_adapters/abstract/database_statements.rb:194:in `transaction'
    from /Users/branch/.rvm/gems/ruby-1.9.3-p484/gems/activerecord-3.1.12/lib/active_record/transactions.rb:208:in `transaction'
    from /Users/branch/.rvm/gems/ruby-1.9.3-p484/gems/activerecord-3.1.12/lib/active_record/transactions.rb:293:in `with_transaction_returning_status'
    from /Users/branch/.rvm/gems/ruby-1.9.3-p484/gems/activerecord-3.1.12/lib/active_record/transactions.rb:246:in `save!'
    from (irb):16
    from /Users/branch/.rvm/gems/ruby-1.9.3-p484/gems/railties-3.1.12/lib/rails/commands/console.rb:45:in `start'
    from /Users/branch/.rvm/gems/ruby-1.9.3-p484/gems/railties-3.1.12/lib/rails/commands/console.rb:8:in `start'
    from /Users/branch/.rvm/gems/ruby-1.9.3-p484/gems/railties-3.1.12/lib/rails/commands.rb:40:in `<top (required)>'
    from script/rails:6:in `require'
    from script/rails:6:in `<main>'
1

**

When i try to save Order via console. the primary key is getting saved as nil.

o = st.orders.new(:store_order_id => "1M",:date_time => Time.now)

here is what i see when i

o.save

#<Order id: nil, store_order_id: "12121M", date_time: nil>

below is a preview my Order Controller Create code

def create
@order = @store.orders.new(params[:order])
@order.save

end

Answer 1

You issue is that you can't do this:

validates_presence_of :order_id

in the Item model. The reason is simple: the Order id is created after validation and thus doesn't exist.

There are a couple of things to do:

1. add inverse relationships
2. Change your validation to simply check for the presence of "order", not "order_id"

Here's the code:

class Order < ActiveRecord::Base 
  has_many :items, :inverse_of => :order, :dependent => :delete_all
end

class Item < ActiveRecord::Base 
  belongs_to :order, :inverse_of => :items
  validates_presence_of :order
end