Insert data into multiple tables from one controller/view [Rails 4] - ruby-on-rails

Question

I have more curious questions for all you amazing people!
I am creating a forum and when you create a topic, you are also creating the first post at the same time.
I need to assign variables to certain fields.
Example: :user_id => current_user.id,
I don't have the param settings correct, so many of the fields are NULL when stored in the database.
Models
class Topic < ActiveRecord::Base
belongs_to :forum
has_many :posts, :dependent => :destroy
belongs_to :user
accepts_nested_attributes_for :posts
end
class Post < ActiveRecord::Base
belongs_to :topic
belongs_to :user
end
Topics Controller
# GET /topics/new
def new
#topic = Topic.new
#topic.posts.build
end
def create
#topic = Topic.new(topic_params)
if #topic.save
##topic.responses = Post.new(params[:responses])
flash[:success] = "Topic Posted"
redirect_to "/forums/#{#topic.forum_id}"
else
render :new
end
end
def topic_params
# last_post_at = (:last_post_at => Time.now)
params.require(:topic).permit(
:name,
:description,
[:last_poster_id => current_user.id],
[:last_post_at => Time.now],
[:user_id => current_user.id],
:forum_id,
posts_attributes: [:id, :content, :topic_id, :user_id => current.user.id] )
end
Post Controller
# GET /posts/new
def new
#post = Post.new
end
def create
#post = Post.new(
:content => params[:post][:content],
:topic_id => params[:post][:topic_id],
:user_id => current_user.id)
if #post.save
#topic = Topic.find(#post.topic_id)
#topic.update_attributes(
:last_poster_id => current_user.id,
:last_post_at => Time.now)
flash[:notice] = "Successfully created post."
redirect_to "/topics/#{#post.topic_id}"
else
render :action => 'new'
end
end
_form for View/Topic
<%= form_for(#topic) do |f| %>
<% if params[:forum] %>
<input type="hidden"
id="topic_forum_id"
name="topic[forum_id]"
value="<%= params[:forum] %>" />
<% end %>
<div class="field">
<%= f.label :name %><br>
<%= f.text_field :name %>
</div>
<div class="field">
<%= f.label :description %><br>
<%= f.text_field :description %>
</div>
<%= f.fields_for :posts do |p| %>
<%= p.label :content %><br />
<%= p.text_area :content %>
<% end %>
<%= f.submit :class => "btn btn-primary" %>
<% end %>

Answer 1

You'll likely be looking for a function called:
accepts_nested_attributes_for
You put this into the model you're working with (in your case Post) and it will pass paeans for the nested model through to the corresponding controller
There is a good RailsCast about this and I've gr some experience with it too. If you want me to post working live code, let me know (I'm on my iPhone)
Live Code
Models
#app/models/image_post.rb
belongs_to :post, :class_name => 'Post'
belongs_to :image, :class_name => 'Image'
accepts_nested_attributes_for :image, :allow_destroy => true
#app/models/post.rb
has_many :images, -> { uniq }, :class_name => 'Image', :through => :images_posts, dependent: :destroy
has_many :images_posts, :class_name => 'ImagePost'
accepts_nested_attributes_for :images_posts, :allow_destroy => true
Controller
def new
#post = Post.new
#post.images_posts.build.build_image
end
def create
#Using Inherited Resources Gem
create!
end
private
def permitted_params
{:post => params.require(:post).permit(:title, :body, images_posts_attributes: [:caption, image_attributes: [:image]] )}
end
Form
<%= form_for [:admin, resource], :html => { :multipart => true } do |f| %>
<table class="resource_table">
<thead>
<th colspan="2"><%= params[:action].capitalize %> <%= resource_class %></th>
</thead>
<tbody class="form">
<% attributes.each do |attr| %>
<tr class="<%= cycle('odd', '')%>">
<td><%= resource_class.human_attribute_name(attr) %></td>
<td>
<% if attr == "body" %>
<%= f.text_area attr, :rows => 60, :cols => 80, :class => "redactor" %>
<% else %>
<%= f.text_field attr, :value => resource.public_send(attr).to_s %>
<% end %>
</td>
</tr>
<% end %>
<%= f.fields_for :images_posts do |images_posts| %>
<%= images_posts.fields_for :image do |images| %>
<tr>
<td>Image</td>
<td><%= images.file_field :image %></td>
</tr>
<% end %>
<tr>
<td>Caption</td>
<td><%= images_posts.text_field :caption %></td>
</tr>
<% end %>
<tr class="dull">
<td colspan="2"><%= f.submit "Go" %></td>
</tr>
</tbody>
</table>
<% end %>

Answer 2

Use accepts_nested_attributes
class topic
accepts_nested_attributes :posts
end
class post
accepts_nested_attributes :topic
end
Then in form you can use fields_for posts while creating topic form
Also in post form fileds_for for topic

Answer 3

You may want to fetch the post params as
params[:topic].fetch(:post_attributes, nil)
Rails 4 has been sanitized the mass-assignment to be called as strong_params
Example