I have a scenario where the models look like
开发者_如何学Pythoncreate_table :users do |t|
t.string :name
t.timestamps
end
create_table :blogs do |t|
t.string :url
t.string :title
t.text :description
t.timestamps
end
create_table :posts do |t|
t.integer :user_id, :null => false
t.integer :blog_id, :null => false
t.text :post_text
end
class Blog < ActiveRecord::Base
has_many :users, :through =>:posts
has_many :posts, :dependent=>true
end
class User < ActiveRecord::Base
has_many :blogs
has_many :posts, :through=>:blogs
end
class Post < ActiveRecord::Base
belongs_to :blog
belongs_to :user
end
The question I have is: 1. When a user is created, I would like to create a blog for him automatically.
@user = User.find_or_create_by_name(user_name)
How do I go about creating a blog? @blog = Blog.find_or_create_by_user_id(@user)
I am getting the following error:
undefined method `find_or_create_by_user_id' for #<Class:0x1044735b0>
@blogs = @user.blogs
gives me:
Mysql::Error: Unknown column 'blogs.user_id' in 'where clause': SELECT * FROM `blogs` WHERE (`blogs`.user_id=1234)
I know Blogs table does not have user_id column. But isn't the join supposed to take care of it? What am I doing wrong here?
Thanks for your help
To use the Post model as the association table, the User model needs to be tweaked to properly demonstrate the association. Once done, you could use after_create
to create a new blog for a newly created user.
class User < ActiveRecord::Base
has_many :posts
has_many :blogs, :through=>:posts
after_create :add_blog
private
def add_blog
blogs << Blog.new
end
end
EDIT:
The best I know how to handle it is to explain what I "think" the relationships are attempting to accomplish then you tell me where I'm off and we go from there.
1) A User can "own" many blogs
2) A blog can have many posts
3) A post belongs to a single user and to a single blog
4) a blog can only have one "owner" (user)
5) Blogs can be "owned" by many users thereby giving them permission to post.
If 1-4 are true, and 5 false... that isn't a "has_many :through" scenario or many-to-many relationship, just one-to-many relationships.
Accordingly, posts should not be used as an association table. There isn't an association table needed.
add t.integer :user_id, :null => false
to the blogs table
class Blog < ActiveRecord::Base
belongs_to :users,
has_many :posts, :dependent=>:destroy # rec'd error in RoR3... replaced true with :destroy
end
class User < ActiveRecord::Base
has_many :blogs, :dependent=>:destroy
has_many :posts
after_create :add_blog
private
def add_blog
blogs << Blog.new
end
end
class Post < ActiveRecord::Base
belongs_to :blog
belongs_to :user
end
If 5 is true, this would be a true many-to-many... but I don't think that's what you're attempting to do.
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