Best way to do this

rubyonrails-talk
1

I'm looking to give an object (buyer) a status. What's the best way to accomplish this? At the moment, I'm struggling to comprehend my way through the following:

1) Create a status model, then let the user add statuses as they see fit. These statuses can then be applied to a buyer. The buyer table will have a status_id column. This works fine, but I have a problem when I try to refer to the the status through a buyer.

buyer.status gives me the following error:

Unknown column 'statuses.buyer_id' in 'where clause': SELECT * FROM `statuses` WHERE (`statuses`.buyer_id = 12) LIMIT 1

I see what it's trying to do - go into the status column and find all statuses that have the buyer_id assigned. The problem is that I don't want a status to apply to only ONE buyer, I want them to be able to apply to multiple.

I'm sure I'm missing something in my routes, or just not understanding the relationship and how I need to instruct rails of this.

Can someone help me out? Thanks in advance for any time spent helping.

2

I'm beginning to think there needs to be a third table; one whose columns are:

id, buyer_id, status_id

This would be my first time doing it like this though, so I sort of get stuck understanding how the route is supposed to work.

3

Sounds like you do not have your associations defined correctly in your model.

In your Buyer model you should have this line:

    belongs_to :status

In your Status model you should have this line:

    has_many :buyers

HTH,

Jamey

4

Jamey Cribbs wrote:

Sounds like you do not have your associations defined correctly in your model.

In your Buyer model you should have this line:

    belongs_to :status

In your Status model you should have this line:

    has_many :buyers

HTH,

Jamey

That was it! Thank you so much. I was totally getting confused here:

belongs_to :status vs. has_one :status

Can you help me understand why it's belongs_to and not has_one? A status is part of a buyer, so I guess I just get confused on the logic.

5

The big difference between has_one and belongs_to is that ActiveRecord expects the model that uses the belongs_to to have a foreign key identifying the associated record in the other table. So, therefore you know you need to use a belongs_to in Buyer because that the buyers table is where you have defined the status_id field.

HTH,

Jamey

6

Steve Castaneda wrote:

Jamey Cribbs wrote:

Sounds like you do not have your associations defined correctly in your model.

In your Buyer model you should have this line:

    belongs_to :status

In your Status model you should have this line:

    has_many :buyers

HTH,

Jamey

That was it! Thank you so much. I was totally getting confused here:

belongs_to :status vs. has_one :status

Can you help me understand why it's belongs_to and not has_one? A status is part of a buyer, so I guess I just get confused on the logic.

has_one is just like has_many except for different cardinality: it means that this table doesn't contain the foreign key.

If you had read the docs for the Associations module, you would have seen this very point clearly explained.

Best,