accepts_nested_attributes_for with has_many => :through Options - ruby-on-rails

Question

I have two models, links and tags, associated through a third, link_tags. The following code is in my Link model.
Associations:
class Link < ActiveRecord::Base
has_many :tags, :through => :link_tags
has_many :link_tags
accepts_nested_attributes_for :tags, :allow_destroy => :false,
:reject_if => proc { |attrs| attrs.all? { |k, v| v.blank? } }
end
class Tag < ActiveRecord::Base
has_many :links, :through => :link_tags
has_many :link_tags
end
class LinkTag < ActiveRecord::Base
belongs_to :link
belongs_to :tag
end
links_controller Actions:
def new
#link = #current_user.links.build
respond_to do |format|
format.html # new.html.erb
format.xml { render :xml => #link }
end
end
def create
#link = #current_user.links.build(params[:link])
respond_to do |format|
if #link.save
flash[:notice] = 'Link was successfully created.'
format.html { redirect_to links_path }
format.xml { render :xml => #link, :status => :created, :location => #link }
else
format.html { render :action => "new" }
format.xml { render :xml => #link.errors, :status => :unprocessable_entity }
end
end
end
View code from new.html.erb:
<% form_for [current_user, #link], :url => account_links_path do |f| %>
<%= render :partial => "form", :locals => { :f => f } %>
<% end %>
And the corresponding partial:
<%= f.error_messages %>
<p>
<%= f.label :uri %><br />
<%= f.text_field :uri %>
</p>
<p>
<%= f.label :title %><br />
<%= f.text_field :title %>
</p>
<h2>Tags</h2>
<% f.fields_for :tags_attributes do |tag_form| %>
<p>
<%= tag_form.label :name, 'Tag:' %>
<%= tag_form.text_field :name %>
</p>
<% unless tag_form.object.nil? || tag_form.object.new_record? %>
<p>
<%= tag_form.label :_delete, 'Remove:' %>
<%= tag_form.check_box :_delete %>
</p>
<% end %>
<% end %>
<p>
<%= f.submit 'Update' %>
</p>
The following line of code, in the create action in the Link controller throws an error:
#link = #current_user.links.build(params[:link])
The error: Tag(#-621698598) expected, got Array(#-609734898)
Are there additional steps needed in the has_many => :through case? These seem to be the only indicated changes for the basic has_many case.

Answer 1

Take a look at the line of your code
<% f.fields_for :tags_attributes do |tag_form| %>
You need to use just :tags instead of :tags_attributes.
This will solve your issue
Make sure that You have build links and tags in your controller like
def new
#link = #current_user.links.build
#link.tags.build
end

Answer 2

I found this here on stackoverflow:
Rails nested form with has_many :through, how to edit attributes of join model?
please tell me if it worked.

Answer 3

In order for this to work, you need to pass in the right params hash:
params = {
:link => {
:tags_attributes => [
{:tag_one_attr => ...}, {:tag_two_attr => ...}
],
:link_attr => ...
}
}
And your controller will look like:
def create
#link = Link.create(params[:link]) # this will automatically build the rest for your
end

Answer 4

Try this:
<% f.fields_for :tags_attributes do |tag_form| %>

Answer 5

In your controller in the new action (that loads the form partial), are you building a #tag through your link?
So you should see something along the lines of:
#link = Link.new
#tag = #link.tags.build
It might be best to post the contents of the new and create action of your links_controller.

Answer 6

try
<% f.fields_for :tags do |tag_form| %>
(ie lose the _attributes in :tag_attributes) That's how I've usually done nested forms

Answer 7

You need to build a tag in your controller or in the view
def new
#link = #current_user.links.build
#link.tags.build
end
#in your view you can just use the association name
<% f.fields_for :tags do |tag_form| %>