I built the migration:
class ExpensesVendorJoinTable < ActiveRecord::Migration
def self.up
create_table :expenses_vendor, :id=>false do |t|
t.integer :expenses_id
t.integer :vendor_id
t.timestamp :created_at
end
end
def self.down
drop_table :expenses_vendor
end
end
I applied the migration and checked the resulting join table:
mysql> show columns in expenses_vendor;
+-------------+----------+------+-----+---------+-------+
| Field | Type | Null | Key | Default | Extra |
+-------------+----------+------+-----+---------+-------+
| expenses_id | int(11) | YES | | NULL | |
| vendor_id | int(11) | YES | | NULL | |
| created_at | datetime | YES | | NULL | |
+-------------+----------+------+-----+---------+-------+
3 rows in set (0.00 sec)
How do I modify my Expense.new from vendor-lookup via
<%# @vendors = Vendor.all -%>
<%# def name; Vendor.nickname; end -%>
<%#= f.collection_select(:vendor, :vendor_id,
@vendors, :id, :name) -%>
so that the user can select a vendor from a drop-down and only the
selected vendor's ID will be saved in the join-table,
rather than the vendor's name saved in the expense record.
This should be my last hurdle for this application. Any guidance will
be most appreciated. I didn't see an answer on the sites we've talked
about.
Thanks in Advance,
Richard
On Jul 12, 9:45 pm, Marnen Laibow-Koser <[email protected]> wrote:
> RichardOnRails wrote:
> > On Jul 12, 8:24 pm, Marnen Laibow-Koser <[email protected]> wrote:
> >> RichardOnRails wrote:
> >> > I just added these linkage statements to my Expense and Vendor models,
> >> > respectively.
>
> >> Which? You neglected to say.
>
> > Change the Expense model:: app\models\expense.rb
> > class Expense < ActiveRecord::Base
> > belongs_to :vendor # Added
> > end
>
> > Change the Vendor model:: app\models\ vendor.rb
> > class Vendor < ActiveRecord::Base
> > has_many :expenses # Added
>
> > def name
> > #{qbname} # QuickBooks name
> > end
> > end
>
> #{} syntax is only valid within double-quoted strings.
>
>
>
> >> > webpage (http://www.railsforum.com/viewtopic.php?id=265).
>
> >> Why are you following tutorials from 2006, before Rails 1.0 even
> >> existed?
>
> > Because it was the simplest one I stumbled across.
>
> Who cares how simple it is if it's obsolete?
>
> [...]
>
> >> > That leads me to think that I need to:
> >> > 1. Create migration Add_Vendor_ID_to_Expense and then add column
> >> > vendor_id of type integer, or something like that.
> >> > 2. Create migration Add_Expense_ID_to_Vendor and then add column
> >> > expense_id of type integer, or something like that.
>
> >> You don't need both.
>
> > Why not? And if not, does it matter which one I use?
>
> The Rails associations documentation explains which one you need.
> Perhaps you should go read that (it's the docs for the module that
> contains the has_many and belongs_to methods).
>
>
>
> >> > 3. Create migration Create_Expense_Vendor_Table and then add
> >> > expense_id and vendor_id columns.
>
> >> You may not need this at all.
> > Really. You mean Active Record is smart enough to decipher this from
> > the mere fact that I added those one-liners to the respective models?
>
> No, I mean that you don't need a join table in this case, for reasons
> related to relational DB design and having nothing to do with Rails or
> ActiveRecord at all.
>
> I *would* however advise using the Foreigner plugin to put foreign key
> constraints in the DB.
>
> The fact that you're asking these questions makes me think that you know
> very little about relational database design. So put aside Rails for a
> day or two and go learn. In particular, learn about the proper use of
> foreign keys, and about normalization, especially as far as the Third
> Normal Form (3NF). Wikipedia has some excellent articles on these
> topics.
>
>
>
> >> And it should all be in one migration class if it represents one
> >> conceptual change.
> > I thought of that but decided to go with my first thought.
>
> ...because...?
>
>
>
> > Again, best wishes,
> > Richard
>
> Best,
> --
> Marnen Laibow-Koserhttp://www.marnen.org
> [email protected]
> --
> Posted viahttp://www.ruby-forum.com/.
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