Forum Series Part 3: Nested Attributes and fields_for Discussion

What do you think about using ActiveForm? https://github.com/rails/ac...

Also there is a gem `reform` for helping with this is https://github.com/apotonic...

What markdown parser gem did you use for this episode Chris?

You flew by the form pretty fast. Can you include that code on this page as well. I don't have the view files, so create them manually? Thanks!

I'm very new at this, so I have a few questions.

How come my forum_threads_controller was blank, but the video started with some code already?

Also, my views folder has none of the same files that the video has at this point? Are will we be creating these as we go?

I have tried this but seem to have a problem.

When I do:

def new
@post = Post.new
@post.content.build
end

I get a undefined method 'build' for nil:class

but it will work if I do this:

def new
@post = Post.new
@post.build_content
end

My models:

Post.rb
has_one: :content, dependent: :destroy
accepts_nested_attributes_for :content

Content.rb
belongs_to :post

Any ideas why?

Hi Chris, How can I make it create x amount of posts, specified by the thread starter, each with a different subject, again specified by the thread starter. For example:
New thread Name= Cars
Post= Mercedes
Post= BMW
Post= Porsche
Is there an easier way to do this? what i basically want is kind of a thread within a thread

Hi Chris! I'd like to create a form for a product model, where users can choose a product category first and then can fill the form out. This would be easy, but I'd like to show them different attributes based on the chosen category. Something like if they choose book category, then they will have fields like title, author, published_at, but if they choose shoes category then they can fill out the size, color and type fields. What is the good approach in this case? Should I create more different models like (shoes,books, etc.) or something else? I saw some tuts about dynamic form, but as far as I understand it, I don't need that since the form fields will be predefined and users won't be able to add extra fields.

Hi Chris, great videos! What are your thoughts about using simple_form gem instead of the built in form_for helper? Are there any advantages/disadvantages using this gem?

Simple from gem: https://github.com/platafor...

This episode was hard to follow because there was a lot added that wasn't covered on video.

If someone is using Rails 5, notice that "the relational model MUST need the foreign key to create the instance", because the forum_thread has not created yet, the foreign key in forum_post is missing.

In Rails 5, need to add ', optional: true' to forum_post.rb

'belongs_to :forum_thread' >>> 'belongs_to :forum_thread, optional: true'

Thank you :)

forum_threads_controller
class ForumThreadsController <ApplicationController

before_action :authenticate_user!, except: [:index,:show]
before_action :set_forum_thread,except: [:index,:new,:create]

def index
@forum_threads = ForumThread.all

end

def new
@forum_thread = ForumThread.new
@forum_thread.forum_posts.new
end

def create
@forum_thread = current_user.forum_threads.new forum_thread_params
if @forum_thread.save
redirect_to @forum_thread
else
render action: :new
end

end

def show

end

private
def set_forum_thread
@forum_thread = ForumThread.find(params[:id])
end

def forum_thread_params
params.require(:forum_thread).permit(:subject,forum_posts_attributes:[:body])
end
end

forum_posts_controller
class ForumPostController < ApplicationController

def index
@forum_posts = @ForumPost.all
end

def new
@forum_post = @ForumPost.new
end

def edit

end

def show

end

def create

end
end

form partial

<%= form_with model: @forum_thread do |form| %>

<%= form.text_field :subject, palceholder: "subject", class: "form-control" %>

<%= form.fields_for :forum_posts do |p| %>

<% end %>

forum_thread> new.html.erb
<%= render 'forum_threads/form' %>

Shows
unknown attribute 'forum_thread_id' for ForumPost.