Kaminari: paginate a scoped model. Controller/View responsibility - ruby-on-rails

I'm not sure i've entitled the question correctly.
In my project I have a categories controller with show action
def show
#category = Category.find params[:id]
end
And in my view I render all the posts associated with this category
#category.posts.each do |post|
link_to post.title, post
So now I want to add pagination with kaminari.
I believe I could just change #category.posts.each to #category.posts.page(params[:page]).each, but I also think that this should be responsibility of the controller. Or am I wrong? Maybe it's totally fine?
Thanks everyone.

Your show method should look like this:
def show
#posts = Category.find(params[:id]).posts.page(params[:page])
end
And in view:
#posts.each do |post|

Related

rails link_to - pass hash of values to controller action

I have retrieved some records based on condition in a hash - #special_products. Now I want to pass the hash to a non-restful action(:special)/ of the same controller so that I can view the products.
I've tried this but how can link_to pass hash and how should the value be retrieved in action: special? which is in the same products_controller?Many thanks.
products_controller.rb
def show
#special_products = Product.by_company
end
show.html.erb
<%= link_to "Special Products", special_path(:anchor => "#{#special_products}") %>
If you're hitting the show action of the Products controller, you should be showing a product.
If you want to show a product in a special way, use the same show action, but render a different view for it.
def show
#product = Product.find(params[:id])
render #product.special? ? 'special_show' : 'show'
end
If you want to list some products in a different way (a filtered collection), you want to use an index. E.g. the products#index action.
def index
#products = Products.not_special
#special_products = Products.way_special
end
# app/views/products/index.html.erb
Special Products:
<%= #special_products.pluck(:name).to_sentence %>
Finally, note that the parameters you pass to link_to end up in the linked URL, which means that your example link_to is going to render something like #<Array []> in the href attribute.

Rails - Partial in another view can't access its controller

I'm trying to build a profile page that displays posts sent only to the requested user, and allows the visitor to write a post of their own. Because this simplified example should have two distinct controllers: users and posts, I made partials for each post action to render within the user's show action.
Directory structure for my views directory looks like this:
- posts
- _index.html.erb
- _new.html.erb
- users
- show.html.erb
... (etc.)
Section that displays these partials within the user's show.html.erb:
<section>
<h3>Posts:</h3>
<%= render '/posts/new', :post => Post.new %>
<%= render '/posts/index', :posts => Post.where(target_id: params[:id]) %>
</section>
I eventually found out that you could pass variables into the partial in this render line, and though this works, it's very messy and probably doesn't follow the best practices.
Ideally, I'd want these partials to be connected with the posts controller so I can write more complex database queries in a place that isn't the view:
class PostsController < ApplicationController
def new
#post = Post.new
end
def index
#posts = Post.where(target_id: params[:id])
end
def create
#post = Post.new(post_params)
#post.user_id = current_user.id
#post.target_id = params[:post][:target_id]
if #post.save
redirect_to :back, notice: 'You published a post!'
else
render new
end
end
private
def post_params
params.require(:post).permit(:body)
end
end
Currently, I haven't found a way of doing this. I know this is a newb question, but thanks for any help in advance.
You are attempting to treat your controllers like models: doing the post work in post controller and the user work in user controller. But controllers are task-oriented, not model-oriented.
Since you want posts info in your user form, it's typical to gather it in the user controller. E.g.
class UsersController < ApplicationController
def show
...
#posts = Post.where(user_id: user.id)
end
end
That #posts instance variable is visible in the show template and any partials it calls. But many coders prefer to send it explicitly through render arguments, as more functional:
<%= render '/posts/post_list', posts: #posts %>
For one thing it's easier to refactor when you can see at a glance all of the partial's dependencies.
I agree somewhat with #Mori's advice. As he said, you are trying to put too much logic into the controller. I think this was a result of you trying to get it out of the view, which is the right idea, but you want business logic to be in the model.
Also, those index and new actions for PostsController are never going to be called. When you are calling the render posts/new for example, that is rendering the view, not the controller action. So, those controller actions have no reason to exist.
I would implement the fix in perhaps a different way than Mori described. It's a recommended practice to try and pass as few instance variables from the controller to the view as possible (see 3rd bullet in the linked section).
Since it's really the show action of the UsersController we are talking about here, I as someone trying to understand your code would assume the instance variable you are passing to the show view is something like #user.
You may want to use an includes method when instantiating the #user object. The includes statement will allow you to load the additional models you will need to instantiate using the minimum number of queries possible (preventing an N+1 query situation). You probably don't want to load every single one if there are thousands of matching posts, so I put an arbitrary limit of 10 on that.
UsersController
def show
#user = User.find(params[:id]).includes(:received_posts).limit(10)
end
#....
View
<section>
<h3>Posts:</h3>
<% unless #user.id == current_user.id %>
<%= render 'posts/form', post: Post.new(user_id: #user.id) %>
<% end %>
<%= render #user.received_posts %>
</section>
Putting the partial for a new post instead as a view called posts/form will allow you to reuse that form if you want to render an edit action (form_for knows which action to use on submit by calling the passed model's persisted? method).
Note that this code assumes the User model has the second relationship with posts set up to be called received_posts, but you can change it to whatever reflects the reality. By passing the received_posts collection to the render method, Rails is smart enough to know that if you want to render a collection of Post models to look for a posts/_post partial and render one for each Post. It's a little cleaner looking IMO. Just make sure to move your posts/show code into that. posts/show implies this is its own action and not something used as a partial for something else.

How to display all posts with all its comments - Ruby on Rails

I'm new to rails and don't know how to achieve this in rails. It might be a really stupid question. But it was not covered in the RoR Codecademy course I did and could not fint a answer elsewhere.
So I have two tables, posts and comments that have an one-to-many relationship. One post has many comments.
I want to display all post with all its comments underneath. What would be the correct way to do this?
There are two ways to do this:
First: you can do like this way in your post controller action (suppose :index) do:
def index
#posts = Post.all
end
And in your index.html.erb
<% #posts.each do |post|%>
# Your post attribute like name etc
<% post.comments.each do |comment|%>
# Your post attribute like name etc
<% end %>
<% end %>
Second: in your post controller action do:
def index
#posts = Post.all.includes(:comments)
end
And in your index.html.erb
<% #posts.each do |post|%>
# Your post attribute like name etc
<% post.comments.each do |comment|%>
# Your post attribute like name etc
<% end %>
<% end %>
Difference in above two ways is that in first one there is always a data base call when you do "post.comments" but in second there is only two data base call i.e. "Post.all.includes(:comments)", no data base call at view part, so it is up to you which way you want to use.
If a Post has_many comments then:
post = Post.find(1)
post.comments.each do |comment|
# do something with each comment here
end

form_tag action not working in rails

I have this form in my application.html.erb.
<%= form_tag(:action=>"index", :controller=>"posts") %>
<p>
// code here
</p>
I dont understand why is this getting directed to posts->create instead of posts->index?
Thanks.
Basically, Rails observes and obeys "RESTful" web service architecture. With REST and Rails, there are seven different ways to interact with a server regarding a resource. With your current code, specifying the form's action as index doesn't make sense: Rails' form helpers can either POST, PUT or DELETE.
If you wanted to create a post, then redirect to the index, you can do so in the applicable controller action:
class PostsController < ApplicationController
...
def create
#post = Post.new
respond_to do |format|
if #post.save
format.html { redirect_to(:action => 'index') }
end
end
While your form would look like:
<% form_for #post do |f| %>
# put whatever fields necessary to create the post here
<% end %>
You seem to be a little mixed up with respect to the uses for each action. Here's a quick summary of typical RESTful usage:
Index -> view a list of items
New/Edit -> form where items are added or edited
Create/update -> controller action where items are created/updated
The reason your routes file is not taking you to index is because index is not an action where posts are typically created or updated. The best way is to go RESTful. Unless you have a very unusual situation, the best way to set your system up is probably a little like this:
# routes.rb
resources :posts
# application.html.erb (or better: posts/_form.html.erb).
<% form_for #post do |f| %>
<% end %>
# posts controller, whichever action you want to use
def new
#post = Post.new
end
By putting the form in a partial called form you can access it in new, edit, or wherever else you need to manipulate a post in your system.

undefined method 'each' Ruby on Rails

Apologies in advance, I am a newbie trying to get my head around rails.
My View at the bottom works when I use:
def show
#posts = Post.all
end
However in my controller I now have:
def show
#posts = Post.find_by_category_id params[:id];
end
In my view I have
<%= #posts.each do |post| %>
<%= post.title %>
<% end %>
Some please explain why I get this error. What should I use. category_id is a foreign key on the Post table.
Look at http://api.rubyonrails.org/classes/ActiveRecord/FinderMethods.html#method-i-find_by
Finds the first record matching the specified conditions
find_by_ will return only one post, not a collection. So you are not able to use each.
try
def show
#posts = Post.all.find_by_category_id params[:id];
end

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