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Replacing partial with AJAX in Rails 4: undefined method `id`

When replacing a partial through Ajax, one method is giving me the proper result but the other (almost identical) isn't. I want to select and deselect a group for a specific campaign. Selecting gives me a direct replacement, deselecting doesn't.
models/general_connection.rb
belongs_to :campaign
belongs_to :group
models/group.rb
has_many :general_connections
has_many :campaigns, through: :general_connections
models/campaign.rb
has_many :general_connections
has_many :groups, through: :general_connections
controllers/general_connection.rb
def connect_group_to_campaign
#group = Group.find(params[:group_id])
#campaign = Campaign.find(params[:campaign_id])
#campaign.general_connections.create(group: #group)
respond_to do |format|
format.html { redirect_to :back }
format.js
end
end
def disconnect_group_from_campaign
#general_connection = GeneralConnection.where("group_id = ? AND campaign_id = ?", params[:group_id], params[:campaign_id]).first
#group = #general_connection.group
#general_connection.destroy
respond_to do |format|
format.html { redirect_to :back }
format.js
end
end
views/campaign/show.html.erb
<div class="row">
<% #main_groups.each do |group| %>
<%= render partial: 'groups_form', locals: { group: group } %>
<% end %>
</div>
*views/campaign/_groups_form.html.erb
<div class="row" id="group_<%= group.id %>">
<div class="col m6">
<div class="valign-wrapper black-text">
<% if group.icon.nil? %>
<i class="material-icons">group</i>
<% else %>
<i class="material-icons"><%= group.icon %></i>
<% end %>
&nbsp<%= group.title %>
</div>
</div>
<div class="col m6">
<% if !grouped(group) %>
<%= form_tag connect_group_to_campaign_path(:group_id => group.id, :campaign_id => #campaign.id), remote: true do %>
<%= button_tag 'check_box_outline_blank', class: "secondary-content material-icons grey-text", style: "background-color:white;border:none;" %>
<% end %>
<% else %>
<%= form_tag disconnect_group_from_campaign_path(:group_id => group.id, :campaign_id => #campaign.id), remote: true do %>
<%= button_tag 'check_box', class: "secondary-content material-icons grey-text", style: "background-color:white;border:none;" %>
<% end %>
<% end %>
</div>
</div>
views/general_connection/connect_group_to_campaign.js.erb
$('#group_<%= #group.id %>').replaceWith('<%= j render partial: 'campaigns/groups_form', locals: {group: #group} %>');
views/general_connection/disconnect_group_from_campaign.js.erb
$('#group_<%= #group.id %>').replaceWith('<%= j render partial: 'campaigns/groups_form', locals: {group: #group} %>');
...and this is the error that I'm getting:
ActionView::Template::Error (undefined method `id' for nil:NilClass):
12: </div>
13: <div class="col m6">
14: <% if !grouped(group) %>
15: <%= form_tag connect_group_to_campaign_path(:group_id => group.id, :campaign_id => #campaign.id), remote: true do %>
16: <%= button_tag 'check_box_outline_blank', class: "secondary-content material-icons grey-text", style: "background-color:white;border:none;" %>
17: <% end %>
18: <% else %>
To sum it up: both methods are working, but only connect_group_to_campaign gives a direct result and disconnect_group_from_campaign doesn't and needs a browser refresh.
Can anyone help me out?

It seems #campaign object is not declared in disconnect_group_from_campaign method. Try it after adding the below line in your disconnect_group_from_campaign method
#campaign = Campaign.find(params[:campaign_id])

Implementing AJAX Creation, Missing Template (Create) Error

I am trying to implement AJAX in my to do type app, but am getting a missing template error (Missing template items/create, application/create with {:locale=>[:en], :formats=>[:html], :variants=>[], :handlers=>[:erb, :builder, :raw, :ruby, :coffee]}.) on my create action. There shouldn't be a create.html.erb page because the creation of items happens on a lists#show page:
<div class='new-item'>
<%= render 'items/form' %>
</div>
<div class="js-items">
<% #items.each do |item| %>
<%= div_for(item) do %>
<p><%= link_to "", list_item_path(#list, item), method: :delete, remote: true, class: 'glyphicon glyphicon-ok', style: "margin-right: 10px" %>
<%= item.name %>
<% if item.delegated_to != "" && item.user_id == current_user.id %>
<small>(Delegated to <%= item.delegated_to %>)</small>
<% elsif item.delegated_to != "" && item.user_id != current_user.id %>
<small>(Delegated by <%= item.user_id %>)</small>
<% end %></p>
<% end %>
<% end %>
</div>
And the _form.html.erb partial to which it links:
<div class="row">
<div class="col-xs-12">
<%= form_for [#list, #item], remote: true do |f| %>
<div class="form-group col-sm-6">
<%= f.label :name %>
<%= f.text_field :name, class: 'form-control', placeholder: "Enter Item Name" %>
</div>
<div class="form-group col-sm-6">
<%= f.label 'Delegate To (Not Required)' %>
<%= f.text_field :delegated_to, class: 'form-control', placeholder: "Enter an Email Address" %>
</div>
<div class="text-center"><%= f.submit "Add Item to List", class: 'btn btn-primary' %></div>
<% end %>
</div>
</div>
Here's the create method in the items_controller:
def create
#list = List.friendly.find(params[:list_id])
#item = #list.items.new(item_params)
#item.user = current_user
#new_item = Item.new
if #item.save
flash[:notice] = "Item saved successfully."
else
flash[:alert] = "Item failed to save."
end
respond_to do |format| <<<<ERROR CALLED ON THIS LINE
format.html
format.js
end
end
And here's my create.js.erb file:
<% if #item.valid? %>
$('.js-items').prepend("<%= escape_javascript(render(#item)) %>");
$('.new-item').html("<%= escape_javascript(render partial: 'items/form', locals: { list: #list, item: #new_item }) %>");
<% else %>
$('.flash').prepend("<div class='alert alert-danger'><button type='button' class='close' data-dismiss='alert'>×</button><%= flash.now[:alert] %></div>");
$('.new-item').html("<%= escape_javascript(render partial: 'items/form', locals: { list: #list, item: #item }) %>");
<% end %>
Anyone have any ideas why I am getting this? I tried removing the format.html line from the items_controller but I got an unrecognizable format error.

You can force the form submission to use a JS format, instead of the default HTML format, so that your respond_to block will render the create.js.erb view instead of the create.html.erb view.
<%= form_for([#list, #item], format: :js, remote: true) do |f| %>
Typically, Rails will detect your remote: true option via "unobtrusive JavaScript (ujs)", which will effectively handle the format: :js option for you. There is something unique in your setup that we have not identified, which is requiring you to enforce the format option.
To see that your create.js.erb is working, you can change the line that renders your item partial:
$('.js-items').prepend("<%= escape_javascript(render(#item)) %>");
To render a the item's name, wrapped in a <p> tag:
$('.js-items').prepend("<p>" + <%= #item.name %> + "</p>");
You can customize that line to generate the html that you want to appear for your new list item. Based on your code above, this looks like it will work out for you.
As you finish your to-do app, you can create a partial for your item, and then change that line again so that your partial will be appended to your list of items.

The action 'show' could not be found for CommentsController

I'm all new, and I'm trying to create a blog using Ruby on rails on windows 8.1.
I've made most of it, but it gives me "The action 'show' could not be found for CommentsController".
I've read several places it might be a lack of a javascript, but I have no idea where to post it.
<h1><%= #post.title %> </h1>
<%= #post.text %>
<h2>Comments</h2>
<% #post.comments.each do |comment| %>
<p><%= comment.text %></p>
<p><%= time_ago_in_words comment.created_at %></p>
<p><%= link_to "Delete comment", [#post, comment], :method => :delete, :confirm => "Are you sure?" %></p>
<% end %>
<%= form_for [#post, #post.comments.build] do |f| %>
<p><%= f.text_area :text, :size => '40x10' %></p>
<p><%= f.submit "Post comment" %></p>
<% end %>
<p>
<%= link_to "Tilbage", posts_path %>
|
<%= link_to "Rediger", edit_post_path(#post) %>
|
<%= link_to "Slet", #post, :method => :delete, :confirm => "Er du sikker?" %>
</p>
This is my code in question. Any help is appreciated :)
Edit: If there is other parts you need, just let me know
Edit:
CommentController
class CommentsController < ApplicationController
def create
params.permit!
#post = Post.find(params[:post_id])
#comment = #post.comments.build(params[:comment])
#comment.save
redirect_to #post
end
def destroy
#comment = Comment.find(params[:id])
#comment.destroy
redirect_to #comment.post
end
end
Routes
Rails.application.routes.draw do
get 'comments/create'
get 'comments/destroy'
resources :posts do
resources :comments
end

Button doesn't update in Ajax on Users Index page - Rails Tutorial 4

TLDR: Trying to add a follow/unfollow button to the Users#Index action but when clicking on the button nothing happens.
I have followed Michael Hartl's Rails Tutorial app and now that it's complete I want to add extra functionality for the Follow/Unfollow button. Currently, you can only follow/unfollow a user after visiting their profile page thru the Users Show action. I've attempted to expand this functionality to the Index page of the Users controller so that instead of having to visit each user's profile page in order to follow/unfollow them, a follow button will also appear next to their name in the Index view.
The code that works initially for the follow/unfollow button on the Users Show action:
users_controller.rb
https://gist.github.com/anonymous/9602598
show.htlm.erb for users view
https://gist.github.com/anonymous/9602616
_follow_form.htlm.erb partial for users view
<% unless current_user?(#user) %>
<div id="follow_form">
<% if current_user.following?(#user) %>
<%= render 'unfollow' %>
<% else %>
<%= render 'follow' %>
<% end %>
</div>
<% end %>
_follow.html.erb partial for users view
<%= form_for(current_user.relationships.build(followed_id: #user.id),
remote: true) do |f| %>
<div><%= f.hidden_field :followed_id %></div>
<%= f.submit "Follow", class: "btn btn-large btn-primary" %>
<% end %>
_unfollow.html.erb partial for users view
<%= form_for(current_user.relationships.find_by(followed_id: #user.id),
html: { method: :delete },
remote: true) do |f| %>
<%= f.submit "Unfollow", class: "btn btn-large" %>
<% end %>
create.js.erb inside of my relationships view
$("#follow_form").html("<%= escape_javascript(render('users/unfollow')) %>")
$("#followers").html('<%= #user.followers.count %>')
destroy.js.erb inside of my relationships view
$("#follow_form").html("<%= escape_javascript(render('users/follow')) %>")
$("#followers").html('<%= #user.followers.count %>')
index.html.erb inside of the users view
<%= render #users %>
_user.html.erb partial inside of users view
<li>
<%= gravatar_for user, size: 52 %>
<%= link_to user.name, user %>
<% if current_user.admin? && !current_user?(user) %>
| <%= link_to "delete", user, method: :delete,
data: { confirm: "You sure?" } %>
<% end %>
I've tried a few different approaches that so far have been fruitless
First I tried simply rendering the follow_form partial inside of the _user partial just like it's done for the User Show view
_user.html.erb partial inside of users view
<%= render 'follow_form' if signed_in? %>
this resulted in the following error: NoMethodError in Users#index "undefined method `id' for nil:NilClass" and it hilights the following line of code inside of the follow_form partial
<% if current_user.following?(#user) %>
After mucking around with the variables and the controller for a few hours I finally managed to get the buttons to show properly on the index page with the following code inside of the _user.html.erb partial
<li>
<%= gravatar_for user, size: 52 %>
<%= link_to user.name, user %>
<% if current_user.admin? && !current_user?(user) %>
| <%= link_to "delete", user, method: :delete,
data: { confirm: "You sure?" } %>
<% end %>
<% if current_user.following?(user) %>
<%= form_for(#current_user.relationships.find_by(followed_id: #users),
html: { method: :delete },
remote: true) do |f| %>
<%= f.submit "Unfollow", class: "btn btn-large" %>
<% end %>
<% else %>
<%= form_for(current_user.relationships.build(followed_id: #users),
remote: true) do |f| %>
<div><%= f.hidden_field :followed_id %></div>
<%= f.submit "Follow", class: "btn btn-large btn-primary" %>
<% end %>
<% end %>
</li>
This code however, only shows the correct follow/unfollow buttons for each user but when you click a button nothing happens. I also attempted to edit the JS files with the following code
create.js.erb
$("#follow_form").html("<%= escape_javascript(render('users/unfollow')) %>")
$("#user").html("<%= escape_javascript(render('users/unfollow')) %>")
$("#followers").html('<%= #user.followers.count %>')
destroy.js.erb
$("#follow_form").html("<%= escape_javascript(render('users/follow')) %>")
$("#user").html("<%= escape_javascript(render('users/follow')) %>")
$("#followers").html('<%= #user.followers.count %>')
This didn't have any effect.
The more I tinker with different parts of the code the more it's confusing me. Here is my relationships controller for good measure.
relationships_controller.rb
class RelationshipsController < ApplicationController
before_action :signed_in_user
def create
#user = User.find(params[:relationship][:followed_id])
current_user.follow!(#user)
respond_to do |format|
format.html { redirect_to #user }
format.js
end
end
def destroy
#user = Relationship.find(params[:id]).followed
current_user.unfollow!(#user)
respond_to do |format|
format.html { redirect_to #user }
format.js
end
end
end
I know it's alot but if anyone can help shed some light on my situation I would be very grateful. This is my first venture outside of tutorials and I figured it would be a good idea to try and add features to an already working project instead of start something from scratch.

Just in case anybody was on this question and was still looking for the correct Ajax code. This works with the existing controller and nothing else will have to be changed.
create.js.erb
var indexed_form = "follow_form_<%=#user.id%>"
if ( document.getElementById(indexed_form) ){
var jquery_indexed_form = "#" + indexed_form
$(jquery_indexed_form).html("<%= escape_javascript(render('users/unfollow')) %>");
}
else {
$("#follow_form").html("<%= escape_javascript(render('users/unfollow')) %>");
$("#followers").html('<%= #user.followers.count %>');
}
destory.js.erb
var indexed_form = "follow_form_<%=#user.id%>"
if ( document.getElementById(indexed_form) ){
var jquery_indexed_form = "#" + indexed_form
$(jquery_indexed_form).html("<%= escape_javascript(render('users/follow')) %>");
}
else {
$("#follow_form").html("<%= escape_javascript(render('users/follow')) %>");
$("#followers").html('<%= #user.followers.count %>');
}
_user.html.erb
<div class="col-md-2">
<% unless current_user?(user) %>
<% form_id = user.id.to_s %>
<div id="follow_form_<%= form_id %>">
<% if current_user.following?(user) %>
<%= form_for(current_user.active_relationships.find_by(followed_id: user.id),
html: { method: :delete },
remote: true) do |f| %>
<%= f.submit "Unfollow", class: "btn" %>
<% end %>
<% else %>
<%= form_for(current_user.active_relationships.build, remote: true) do |f| %>
<div><%= hidden_field_tag :followed_id, user.id %></div>
<%= f.submit "Follow", class: "btn btn-primary" %>
<% end %>
<% end %>
</div>
<% end %>
</div>
This is my first post. Yay! Hope it helps someone!

Use the following code in _user.html.erb partial:
<li>
<%= gravatar_for user, size: 52 %>
<%= link_to user.name, user %>
<% if current_user.admin? && !current_user?(user) %>
| <%= link_to "delete", user, method: :delete,
data: { confirm: "You sure?" } %>
<% end %>
<% if current_user.following?(user) %>
<%= form_for(current_user.relationships.find_by(followed_id: user.id),
html: { method: :delete },
remote: true) do |f| %>
<%= f.submit "Unfollow", class: "btn btn-large" %>
<% end %>
<% else %>
<%= form_for(current_user.relationships.build(followed_id: user.id),
remote: true) do |f| %>
<div><%= f.hidden_field :followed_id %></div>
<%= f.submit "Follow", class: "btn btn-large btn-primary" %>
<% end %>
<% end %>
</li>
I made couple of changes to the code in form_for method call in 2 places:
#current_user should be current_user.
Secondly, followed_id: #users should be followed_id: user.id

has_many and accepts_nested_attributes_for with nested forms and jquery/ajax

I'm trying to create a nested form where there is a "+" button which adds fields via jquery and ajax. I am doing it adding a step at once, so untill now I am able to add a simple text pushing the "+" button, but, as I have just said, I want to add some fields.
I have the followings:
new.html.erb
<h1>New Campaign</h1>
<%= form_for #campaign, html: { multipart: true } do |f| %>
....
<div class="goods">
<%= render "goods/good", f: f, child_index: Time.now.to_i %>
</div>
<div class="actions">
<%= link_to '+', add_good_row_path(params[:campaign]=#campaign, params[:f] = f), remote: true, class: 'btn btn-large btn-success' %>
<%= f.submit 'Crea', class: 'btn btn-large btn-warning' %>
</div>
<% end %>
goods/_good.html.erb
<%= f.fields_for :goods, #campaign.goods.build, child_index: child_index do |good| %>
<%= good.text_field :name, placeholder: 'Nome' %>
<%= good.text_area :description, placeholder: 'Descrizione' %>
<%= good.text_field :cost, placeholder: 'Costo' %>
<% end %>
campaigns_controller.rb
class CampaignsController < ApplicationController
....
def add_good_row
respond_to do |format|
format.js
end
end
end
add_good_row.js.erb
$('.goods').append("hello");
I think that I understood the problem, it is to pass a f variable, a #campaign variable and a child_index to the partial, but how can I do that via jquery?
Hope I was clear...

Have a look at this gem.
I think it's what you are looking for
https://github.com/nathanvda/cocoon