Simple relational query in Rails - sql

Question

Let's say I have the following tables:
product transaction
------------------ ------------------
| id | name | | id | product |
------------------ ------------------
| 1 | Product A | | 1 | 2 |
| 2 | Product B | | 2 | 3 |
| 3 | Product C | | 3 | 2 |
------------------ ------------------
Now, let's say I want to make a listing of the transaction table, but I want to display product names instead of product IDs.
In raw SQL, I would do something like this:
SELECT product.name FROM transaction, product WHERE transaction.product = product.id
I'm having a hard time figuring out how this would be done using Rails' Active Record Query Interface. I'm sure this is trivial to you Rails experts out there.

Answer 1

If you want to solve it the "Rails way":
first: change column product in transactions to product_id, and table names should be in plural, otherwise you must add e.g. set_table_name 'transaction' in the models, you will miss a lot of Rails' futures if you don't change it.
add/change these models:
class Product < ActiveRecord::Base
has_many :transactions
end
class Transaction < ActiveRecord::Base
belongs_to :product
end
If you persist on using column name "product" you must change the belongs_to to:
belongs_to :product, :foreign_key => 'product'
but that is kind of ugly
Finally, using this:
Transaction.includes(:product)
Or if you want only those who has a product
Transaction.joins(:product)
Note:
I don't remember exactly, but I think I had problems with using "transactions" as table name in some application. Somebody else perhaps knows about that.

Answer 2

transaction.joins('LEFT OUTER JOIN product ON transaction.id = product.id')