[Rails] Re: big time help(any idea for a proper title..)

thx a lot rick, for taking you time to answer to my problem
yeah, it was a typo it was line_items, instead of list_items.
but...still don'tget something, i'm a rails noob what would you
expect :(

what does rails exactly do when you write li.product =
cart_item.product ???

and wouldn't it be more logical to write something like li.product_id
= cart_item.product_id ???

thx a lot for all your help,
radu

On Dec 19, 5:53 pm, Rick DeNatale <rick.denat...@gmail.com> wrote:
> On Sat, Dec 19, 2009 at 6:34 AM, radu puspana <radupusp...@gmail.com> wrote:
> > Hey guys,
>
> > i ran in some trouble while making an important app for school, and
> > the deadline is so soon, that i took a desperate decision, bother
> > you..
> > I will put up the code here, and if anyone has a solution, it would
> > mean the world to me and my work.
>
> > My problem is this line of code  li.product = cart_item.product
> > because list_items doesn't have a column named product, so what the
> > heck?
>
> I assume that list_items was a typo for line_items.
>
> It shouldn't, it should have an integer column called product_id,
> which references the key (id) of the product record
>
> > The second is that when they interrogate the db, namely the line_items
> > table, the product column doesn't show up, as you can see below:
>
> > depot> sqlite3 -line db/development.sqlite3
> > SQLite version 3.4.0
> > Enter ".help" for instructions
> > sqlite> select * from orders;
> > id = 1
>
> This is order #1
>
> > name = Dave Thomas
> > address = 123 Main St
> > email = custo...@pragprog.com
> > pay_type = check
> > created_at = 2008-06-09 13:40:40
> > updated_at = 2008-06-09 13:40:40
> > --------------------------------------------------------
> > sqlite> select * from line_items;
> > id = 1
> > product_id = 3
>
> This line item belongs  to product #3
>
> > order_id = 1
>
> And it belongs to order #1
>
>
>
> > quantity = 1
> > total_price = 28.5
> > created_at = 2008-06-09 13:40:40
> > updated_at = 2008-06-09 13:40:40
> > sqlite> .quit
> > -------------------------------------------------------
>
> > here is the rest of the code that i have , concerning this problems:
>
> > class CreateOrders < ActiveRecord::Migration
> > def self.up
> > create_table :orders do |t|
> > t.string :name
> > t.text :address
> > t.string :email
> > t.string :pay_type, :limit => 10
> > t.timestamps
> > end
> > end
> > def self.down
> > drop_table :orders
> > end
> > end
>
> > class CreateLineItems < ActiveRecord::Migration
> > def self.up
> > create_table :line_items do |t|
> > t.integer :product_id, :null => false, :options =>
> > "CONSTRAINT fk_line_item_products REFERENCES products(id)"
> > t.integer :order_id, :null => false, :options =>
> > "CONSTRAINT fk_line_item_orders REFERENCES orders(id)"
> > t.integer :quantity, :null => false
> > t.decimal :total_price, :null => false, :precision => 8, :scale => 2
> > t.timestamps
> > end
> > end
> > def self.down
> > drop_table :line_items
> > end
> > end
>
> This looks pretty normal, although most rails apps don't use foreign
> key constraints, but I don't see a problem here.
>
> > class Order < ActiveRecord::Base
> > has_many :line_items
>
>  This says that Order expects the line_items table to have an integer
> order_id field> end
>
> > class Product < ActiveRecord::Base
> > has_many :line_items
>
> This says that Product expects the line_items table to have an integer
> product_id field> # ...
>
> > class LineItem < ActiveRecord::Base
> > belongs_to :order
>
> This pairs up with the association declaration in Order and also
> expects that the line_items table has an order_id field> belongs_to :product
>
> This pairs up with the association declaration in Product and also
> expects that the line_items table has an product_id field
>
> > end
>
> Other than your mistaken expectation that line_items would have a
> product rather than a product_id field, I'm not sure what your problem
> is.
>
> If you need the foreign key field to be product rather than
> product_id, you can use the :foreign_key option on the relevant
> associations to override ActiveRecord's default, and write a migration
> to rename the column. But the only reason to do this would be to
> accomodate an existing non-activerecord app sharing the
> database/table, and in that case you have much less freedom in
> changing the DB schema.
>
> HTH
>
> --
> Rick DeNatale
>
> Blog:http://talklikeaduck.denhaven2.com/
> Twitter:http://twitter.com/RickDeNatale
> WWR:http://www.workingwithrails.com/person/9021-rick-denatale
> LinkedIn:http://www.linkedin.com/in/rickdenatale

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