Rails 4 - association not working correctly - ruby-on-rails-4

Question

I created 2 models using a rails generator like this:
$ bin/rails g model manager name:string
and
$ bin/rails g model blog/post title:string manager:references
With that, I have 2 models files:
# app/models/manager.rb
class Manager < ActiveRecord::Base
has_many :blog_posts
end
and
# app/models/blog/post.rb
class Blog::Post < ActiveRecord::Base
belongs_to :manager
end
going to the rails console I can create a manager and a post like this:
$ manager1 = Manager.new
$ manager1.name = "John Doe"
$ manager1.save
$ post1 = Blog::Post.new
$ post1.title = "Hello World"
$ post1.manager = manager1
$ post1.save
And on console, if I do:
$ post1.manager.name
that works perfectly. Returning the Manager's name. But if I do:
$ manager1.blog_posts
I expected to get the list of manager's posts. But I am getting this error:
NameError: uninitialized constant Manager::BlogPost
The same happing when I try to do Many-to-Relationship between "Blog:Category (app/models/blog/category)" and "Blog::Post (app/models/blog/post.rb)"
UPDATE
#Pavan solved my first problem... And based in that solution, I tried to do the this:
# app/models/blog/post.rb
class Blog::Post < ActiveRecord::Base
belongs_to :manager
has_and_belongs_to_many :blog_categories, class_name: 'Blog::Category', foreign_key: 'blog_category_id'
end
and:
# app/models/blog/category.rb
class Blog::Category < ActiveRecord::Base
has_and_belongs_to_many :blog_posts, class_name: 'Blog::Post', foreign_key: 'blog_post_id'
end
And based on that http://guides.rubyonrails.org/association_basics.html#the-has-and-belongs-to-many-association, I generate the following migration:
class CreateBlogCategoriesPosts < ActiveRecord::Migration
def change
create_table :blog_categories_posts, id: false do |t|
t.belongs_to :blog_post, index: true
t.belongs_to :blog_category, index: true
end
end
end
But when I try this on console:
$ post1 = Blog::Post.first
$ post1.blog_categories
I got this error:
2.2.2 :002 > p.blog_categories PG::UndefinedColumn: ERROR: column blog_categories_posts.category_id does not exist LINE 1:
...log_categories_posts" ON "blog_categories"."id" = "blog_cate...
^ : SELECT "blog_categories".* FROM "blog_categories" INNER JOIN
"blog_categories_posts" ON "blog_categories"."id" =
"blog_categories_posts"."category_id" WHERE
"blog_categories_posts"."blog_category_id" = $1
ActiveRecord::StatementInvalid: PG::UndefinedColumn: ERROR: column
blog_categories_posts.category_id does not exist LINE 1:
...log_categories_posts" ON "blog_categories"."id" = "blog_cate...
^ : SELECT "blog_categories".* FROM "blog_categories" INNER JOIN
"blog_categories_posts" ON "blog_categories"."id" =
"blog_categories_posts"."category_id" WHERE
"blog_categories_posts"."blog_category_id" = $1

Answer 1

NameError: uninitialized constant Manager::BlogPost
You have has_namy :blog_posts defined in manager.rb, so Rails will look for a classname BlogPost which isn't exist in your case.
You should explicitly specify the classname to tell Rails to use it.
# app/models/manager.rb
class Manager < ActiveRecord::Base
has_many :blog_posts, class_name: 'Blog::Post'
end