Create entry for nested model with has_many and through - ruby-on-rails

Question

I have three models with simple associations.
class User < ActiveRecord::Base
has_many :blogs
end
class Blog < ActiveRecord::Base
# Blog has 'title' column
belongs_to :user
has_many :entries
end
class Entry < ActiveRecord::Base
# Entry has 'article' column
belongs_to :blog
end
I'm making an JSON API to create new Entry. One special requirement is to create Blog if not exists. The JSON input should be like
{ "entry" :
{ "article" : "my first blog entry",
"blog" :
{ "title": "My new blog" }
}
}
If the blog exists add the entry to the blog. I'm implementing 'entries#create' method and what I want to do is something like
def create
#user = Users.find(params[:user_id]) # :user_id is given in URL
# I want to do something like
# #user.entries.create(params[:entry])
# or
# #user.create(params[:entry])
# but this doesn't work.
end
What I want to ask here is if I have to manually parse the JSON first and create blog object and then create entry object. If possible I want to make the models accept such input and works correctly.
Another possible solution is to change the API and make it in blogs controller and accept JSON like
{ "blog" :
{ "title" : "My new blog",
"article_attributes" :
{ "article": "my first blog entry" }
}
}
but because of some reasons, I can't make the API like this. (The JSON's first node must be "entry" not "blog")
What I have tried so far is to add "accepts_nested_attributes_for" in the Entry model.
class Entry < ActiveRecord::Base
# Entry has 'article' column
belongs_to :blog
accepts_nested_attributes_for :blog
end
and then post JSON like
{ "entry" :
{ "article" : "my first blog entry",
"blog_attributes" :
{ "title": "My new blog" }
}
}
then in the controller
#user.entries.create(params[:entry])
It seems that Rails tries to create "blog" entry with this code but fails because the "blog_attributes" doesn't include 'user_id'. I can add user_id to the params in my controller but it looks awkward since I'm writing #user.entries.create which should tell which user I'm working on now.
Is there any good way to make it all work as I wanted? (or am I doing something totally wrong?)

Answer 1

Ok remove the accepts_nested_attributes_for :blog from your entry model
And in your blog model put accepts_nested_attributes_for :entries, reject_if: :all_blank, allow_destroy: true
In your JSON do this:
{ "blog" :
{ "title" : "My new blog",
"entry" :
{ "article": "my first blog entry" }
}
}
In your blogs_controller.rb do this:
def blog_params
params.require(:blog).permit(:id, :title, entries_attributes: [:id, :article, :_destroy])
end
and in your blogs_controller.rb new action:
def new
#blog = Blog.new
#blog.entries.build
end
// in your blogs_controller create action:
def create
#user = Users.find(params[:user_id]) # :user_id is given in URL
#user.blog.create(blog_params)
end