confused on how to associate models.

rubyonrails-talk
1

I have Ruser and Bag models. I'm using Ruser instead of User because I know "user" create problems with a postgresql database. Bags must be delivered to Ruser so I need to know when one or more bags are delivered. I create these associations:

class Ruser < ActiveRecord::Base   has_many :deliveries   has_many :bags, :through => :deliveries

class Bag < ActiveRecord::Base   has_many :deliveries   has_many :rusers, :through => :deliveries

class Delivery < ActiveRecord::Base   belongs_to :ruser   belongs_to :bag

Ruser and Bag are already populated. Delivery has delivered_at attribute.

Now I want delivery 3 bags to ruser. I can do bags=Bags.all user=Ruser.find(params[:id]) delivery = user.deliveries.create(:delivered_at => Date.today). But I can't do delivery.bags << bags. I think that could be some mistakes in my associations.

2

You've written that deliver belongs_to bag (ie there is at most one bag for a delivery). With the way your models currently exist, you'd need to create one delivery for each bag.

Fred

3

Msan Msan wrote in post #977110:

I have Ruser and Bag models. I'm using Ruser instead of User because I know "user" create problems with a postgresql database.

You may "know" it, but it ain't true. I use User models in PostgreSQL all the time.

Bags must be delivered to Ruser so I need to know when one or more bags are delivered. I create these associations:

class Ruser < ActiveRecord::Base   has_many :deliveries   has_many :bags, :through => :deliveries

class Bag < ActiveRecord::Base   has_many :deliveries   has_many :rusers, :through => :deliveries

class Delivery < ActiveRecord::Base   belongs_to :ruser   belongs_to :bag

Ruser and Bag are already populated. Delivery has delivered_at attribute.

Now I want delivery 3 bags to ruser. I can do bags=Bags.all user=Ruser.find(params[:id]) delivery = user.deliveries.create(:delivered_at => Date.today). But I can't do delivery.bags << bags. I think that could be some mistakes in my associations.

Of course you can't do delivery.bags . You've specified Delivery belongs_to :bag, which means that there's only one bag for a delivery to be associated with. Perhaps you wanted Delivery has_many :bags.

You probably also wanted Bag belongs_to :delivery : how can one bag be part of several deliveries?

I think you need to analyze the relationships between your models a little better.

Best,

4

That's because rails translate User in users table.

5

What do you mean by that, I do not understand.

Colin

6

Msan Msan wrote in post #977159:

7

nothing important, I work with other frameworks, like grails, that do not pluralized the model name when creating the table so I used not to use "user".

8

You have still not explained why you are not using a class name User and table name users. You appeared to suggest that this is not possible when using PostgreSQL.

Colin

Colin

9

I was confused thinking about grails. With rails "User" can be used, with grails don't.

10

Why not? I have Grails apps with a User domain class that work just fine. Although as a best practice in the Grails world you want to package your domain classes, so it'll probably have a table like com.myco.user.

But I've done quick demo's in Grails with an unpackaged User class with no problem at all.

Best Wishes, Peter

11

It's an OT but the name tables that grails creates are not like you said. If you create a domain class com.myco.user the table that grails create is simply user and postgres doesn't like to have a table called user.