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rails ajax overwriting all partials when refreshing page

I was making a simple variation of the simple example of ajax in rails: http://guides.rubyonrails.org/working_with_javascript_in_rails.html#a-simple-example
I am trying to create a user show view in which new posts are created upon pressing a button. These posts are all listed below the user on the same show page and appear upon creation.
The posts are created fine and shown correctly on the page, however when I refresh the page my
#post = User.posts.build()
Overwrites all the previously created posts giving each of them a nul id.
Also, is it correct to place the create.js.erb in the views folders, or should it go in the assets/javascripts folder?
Here are my files:
UsersController
def show
#user = User.find(params[:id])
#posts = Post.all
#post = #user.posts.build
end
users/show.html.erb
<%= "user-id: #{#user.id}" %>
<ul id="posts">
<%= render :partial => #posts %>
</ul>
<%= form_for(#post, remote: true) do |f| %>
<%= f.hidden_field :user_id, :value => #user.id %>
<%= f.submit %>
<% end %>
PostsController
def create
puts params[:post][:user_id]
#user = User.find(params[:post][:user_id])
puts #user
#post = #user.posts.build()
respond_to do |format|
if #post.save
format.html { redirect_to #post, notice: 'Post was successfully created.' }
format.js {}
format.json { render json: #post, status: :created, location: #post }
else
format.html { render action: "new" }
format.json { render json: #post.errors, status: :unprocessable_entity }
end
Rails.logger.info(#post.errors.inspect)
end
end
def index
#posts = Post.all
#post = Post.new
end
posts/_post.html.erb
<li><%= #post.id %></li>
posts/create.js.erb
$("<%= escape_javascript(render #post) %>").appendTo("#posts");

The Problem
The reason why your partial is rendering all new posts is because you are using the instance variable #post instead of the local variable post inside your partial.
In your UsersController#show action, you set #post = #user.posts.build. When you render <%= #post.id %> inside the partial, you are referencing that same variable which comes from the controller and was set to a new post.
It seems that all the previously created posts are being "null'ed" out, but it's really just that you are continuously rendering a new post, not the existing ones.
The Solution
You need to update your partial to use a local variable, not the instance variable.
<li><%= post.id %></li>
This local variable is automatically provided to you by Rails when you render a collection of records like this
<%= render #user.posts %>
or alternatively
<%= render partial: "posts/post", collection: #user.posts %>
How to Avoid in the Future
This is a really common mistake and can be easy to miss.
For this reason, my recommendation is to stop using instance variables in partials altogether.
Resources
Rails Guides - Rendering Collections
Stop Using Instance Variables In Partials

Found a workaround by avoiding the use of the _post partial to display the older posts:
edit: users/show.html.erb
<ul id="posts">
<% #posts.each do |post| %>
<li>
<%= post.id %>
</li>
<% end %>
</ul>
I don't think this is an ideal solution but it works fine for now.

Yes, you are correct.
create.js.erb with the suffix erb to help you add code ruby to it.
Write code in this file the same with you write javascript code on view html.erb with syntax
<script>
$("<%= escape_javascript(render #post) %>").appendTo("#posts");
</script>

Rails - delete li element with Ajax

I've a users list and I want to delete elements on click of a "delete" link on the same line.
Views:
# users/index.html.erb
<ul class="users">
<%= render #users %>
</ul>
# users/_user.html.erb
<li id="user-<%= user.id %>">
<%= link_to user.email, user %>
<% if current_user.admin? %>
<%= link_to "delete", user, remote: true, method: :delete, data: { confirm: "You sure?" } %>
<% end %>
</li>
Users Controller:
# users_controller.rb
def destroy
User.find(params[:id]).destroy
flash[:success] = "User deleted"
respond_to do |format|
format.html { redirect_to users_url }
format.js
end
end
The javascript to delete the list element is:
# users/destroy.js.erb
$("li#<%= user.id %>").remove();
On click nothing happen, but on page refresh the resource is correctly destroyed. Checking server's LOG I see the following error:
Completed 500 Internal Server Error in 40ms (ActiveRecord: 5.0ms)
ActionView::Template::Error (undefined local variable or method user'
for #<#<Class:0x0000000851d300>:0x00000008e8e7e0>):
1: $("li#<%= user.id %>").remove(); app/views/users/destroy.js.erb:1:in
_app_views_users_destroy_js_erb___2066095411338793994_74738360'
app/controllers/users_controller.rb:46:in `destroy'
Can you pls help me to understand where the error is and why 'user' is undefined? Thanks
edit
I know there are many q&a similar to this question, and I actually build my code consulting these questions. Still, I'm stuck and I need support. Pls do not mark the question as duplicate.

your destroy.js.erb template is not getting the user variable, as it is undefined. try:
def destroy
#user = User.find(params[:id])
#user.destroy
respond_to do |format|
format.html { redirect_to users_url }
format.js
end
end
and
$("li#<%= #user.id %>").remove();
the reason this works is because rails passes data from controller to view by setting variables with # prefix. so you set #user to an instance of the model you grabbed from the database, then you called .destroy on that model, and it got deleted, and then you rendered your destroy.js template which had #user in it as well, and you deleted the list item matching the 'li#233' selector or whatever the id integer was

You're not defining an user variable.
You would save your #user_id in a variable to be accessible in your js.erb. Like that:
def destroy
#user_id = params[:id]
...
end
And then:
$("li#<%= #user_id %>").remove();

Rails Ajax on a form inside an each loop with nested resources and html class

So I am trying to create a list of tasks within a goal and in order to complete them, I am creating a form_for with a hidden field that will update the value for the each task record when clicking submit. I'm trying to add ajax to the form so that when a user hits submit, it will update the record for the task and it will render a partial replacing this form with a div saying "complete!".
goals_controller.rb
def show
#goal = Goal.where(user_id: current_user, id: params[:id]).first
#goal_tasks = #goal.tasks
# This is where the AJAX request will happen
respond_to do |format|
format.html {}
format.js {}
end
end
show.html.erb for Goals
<% #goal_tasks.each do |task| %>
<div class="complete-button">
<% if task.completed == false %>
<%= form_for([#goal,task], remote: true) do |f| %>
<%= f.hidden_field :completed , :value => true %>
<%= f.submit "Complete" , :class => "submit-complete" %>
<% end %>
<% else %>
<%= render partial: "goals/taskcompleted" %>
<% end %>
<div>
<% end %>
show.js.erb
$(".complete-button").html("<%= j(render partial: 'goals/taskcompleted') %>")
The behavior that is happening is that if there are multiple tasks, there are multiple forms with unique id="edit_task_unique_id" in the html but since I'm grabbing the .complete-button class in the show.js.erb. It is replace all of the forms with the complete div. I've tried to somehow grab the unique id's the form creates with each task but no luck. Any help or feedback is appreciated!

Show is a GET type, what you do is a PUT type. You could use update method or create a custom one. You don't even need form, since you don't expect the users to type anything. On the top of that I would use :completed_at field with datetime type. If it's nil then it's not completed, if it's not nil (there is a datetime) then it's completed.
routes.rb
resources :goals do
resources :tasks do
member do
patch :complete
end
end
end
goals/show.html.erb
....
<%= render #tasks %> # this is a rails convention. Basically it iterates thru the #tasks and renders each task based on _task.html.erb which represents a single task.
....
tasks/_task.html.erb
#You use task instead of #task as you do within a #tasks.each |task| do block.
<%= task.name %>
<%= task.content %>
<% if task.completed_at.nil? %>
#here you only need to pass task.id to the path (rails convention again)
<%= link_to "Complete Task", complete_goal_task_path(id: task.id), action: :complete, remote: true, method: :patch %>
<% end %>
goals controller
def show
# I don't know why you wrote this:
#goal = Goal.where(user_id: current_user, id: params[:id]).first
#It should be just this since you are on the show page (You should define the current_user in the view link helper that takes the user on this page.)
#goal = Goal.find(params[:id])
#tasks = #goal.tasks
end
tasks controller
def complete
#task = Task.find(params[:id])
#task.update_attribute(:completed_at, Time.zone.now)
respond_to do |format|
format.html
format.js
end
end
tasks/complete.js.erb
//You remove the completed task from the DOM (I guess you wanna do that.)
$("#task_<%= #task.id %>").fadeOut(400, function(){
$(this).remove();
});
//For flash checkout a stackoverflow question. Something like "how to use flash in js.erb"
schema.rb
create_table "tasks", force: :cascade do |t|
t.integer "goal_id", null: false
t.string "name"
t.text "content", null: false
t.datetime "deadline", null: false
t.datetime "completed_at"
t.datetime "created_at", null: false
t.datetime "updated_at", null: false
end

Can't get remote: true to work with link_to

I can't trigger my js file for some reason. Why is that?
views/categories/_category.html.erb
<%= link_to category.name, articles_path(categotry_id: category.id), remote: true %>
views/articles/index.js.coffee
alert 'I am here'
articles_controller.rb
def index
end

You are missing response format js in index action:
def index
respond_to do |format|
format.js
end
end

I would think you would need to call render in your controller, and have a action, and a route... Try generating a scaffold to see what all you're missing.

Rails flash notice via ajax

Long story short, I have a button. On clicking it, I want an ajax request to be triggered which gets flash[:notice] and displays it in a div in$
Here is my shortened view:
<input type="button" id="search" value="display"/>
<div id="notice">
</div>
My ajax request in the view:
$("#search").submit(function(){
$.ajax({
type: "POST",
url: //url to my show action
success: function(data){
/*$("#notice").html("<%= flash[:notice] %>");
$("#content").html(data);*/
}
});
return false;
});
My controller:
def HomeController < ActionController::Base
def index
end
def show
respond_to do |format|
format.js { flash[:notice] = "" + count.to_s + " results found for " + params[:query][:search_key] + "" }
end
#render :partial => 'search'
end
end
My show.js.erb
#app/views/dashboard_home/show.js.erb
$("#notice").html("<%=j flash[:notice] %>");
$("#content").html("<%=j render partial: "search" %>");
The problem is when I click on button, the notice is displayed fine. But the same notice persists on the next clicks too. The search partial contains the table Please help!

Here is an example that I got working, thanks to Rich Peck's answer. I needed to use flash.now to make sure the flash notice didn't persist.
AJAX trigger in the view:
<%= link_to "Email report", users_path, remote: true %>
Controller:
# app/controllers/users_controller
class UsersController < ApplicationController
def index
# do some things here
respond_to do |format|
format.js { flash.now[:notice] = "Here is my flash notice" }
end
end
end
Rendered view:
# app/views/users/index.js.erb
$("#flash").html('<%= j render partial: "shared/notice_banner" %>');
where the flash notice is displayed in the layout:
# app/views/layouts/application.html.erb
<div id="flash">
<% if notice.present? %>
<%= render partial: "shared/notice_banner" %>
<% end %>
</div>
# app/views/shared/_notice_banner.html.erb
<div data-alert class="alert-box">
<%= notice %>
×
</div>

Sessions
the same notice persists on the next clicks too
This is caused by the flash being stored in the session variable of Rails:
The flash is a special part of the session which is cleared with each
request. This means that values stored there will only be available in
the next request, which is useful for passing error messages etc.
The problem you have is that since I don't think ajax counts as a new request (need reference for this), the data will persist into the next time you request via HTTP.
--
Fix
I would initially try this:
def show
respond_to do |format|
format.js { flash[:notice] = "my secret number "+rand(0,5)+" !" }
end
end
The main problem you have is you're processing the flash variable in your JS using the ERB preprocessor. This is an issue as it means you won't be able to use asset precompile to help it work.
After looking at this question, why not try using the after_filter callback, like this:
#app/controllers/home_controller.rb
Class Home < ActionController::Base
after_filter { flash.discard if request.xhr? }, only: :show
def show
respond_to do |format|
format.js { flash[:notice] = "my secret number "+rand(0,5)+" !" }
end
end
end
--
Update
You should include the success functionality in your show.js.erb:
#app/views/home/show.js.erb
$("#notice").html("<%= flash[:notice] %>");
This means you can remove the whole ajax call from the application.js, and replace with the remote: true for your search form:
#app/views/search/index.html.erb
<%= form_tag home_show_path, remote: true %>
The reason this works is because when you use the format.js respond block, Rails will load the [action].js.erb file in your views. Considering this only happens after the action has been completed, it's equivalent to the success function of your ajax.
By doing this, you'll be able to remove the entire ajax function from your application.js, and replace with the UJS version, as described above