My application has two associated models: Magazine and Article:
class Magazine < ActiveRecord::Base
has_one :article
end
class Article < ActiveRecord::Base
belongs_to :magazine
validation_presence_of :title
end
From the Magazine show page I can create a new Article, so my routes.rb is configured like:
resources :magazines, :shallow => true do
resources :articles
end
and in the Magazine show page I have the link "New article", like:
<%= link_to 'New article', new_magazine_article_path(#article)
and an article helper to pass correct parameters to the form_for:
module ArticlesHelper
def form_for_params
if action_name == 'edit'
[#article]
elsif action_name == 'new'
[#magazine, #article]
end
end
end
so I can use Article form_for like:
<%= simple_form_for(form_for_params) do |f| %> ...
The ArticlesController methods for new and create are:
respond_to :html, :xml, :js
def new
#magazine = Magazine.find(params[:magazine_id])
#article = Article.new
end
def create
#magazine = Magazine.find(params[:magazine_id])
#article = #magazine.build_article(params[:article])
if #article.save
respond_with #magazine # redirect to Magazine show page
else
flash[:notice] = "Warning! Correct the title field."
render :action => :new
end
end
The problem occurs when there is a validation error with the title attribute, and the action new is rendered. In this moment I get the message: undefined method `model_name' for NilClass:Class in the first line of form_for. I think it is because the #magazine parameter passed in the helper.
How could I solve this problem withou use redirect_to ? (I want to mantain the other attributes that were filled in the form .)
Your form_for_params method is returning nil, because the action_name is set to 'create', not 'new' or 'edit'.
Try this:
elseif action_name == 'new' or action_name == 'create'
[#magazine, #article]
Related
I have this newbie error when i want to upvote a "hack" :
ActionController::ParameterMissing at /hacks/6/upvote
param is missing or the value is empty: vote
With Request parameters exemple :
{"_method"=>"post", "authenticity_token"=>"r+fYieTQDsD6fuonr3oe0YEzkzBXH1S8k6bDENS0wCVr3LEpxGA4mps5saM4RQLvBNDVzsm2zXpGm9TKe3ZIYA==",
"controller"=>"hacks", "action"=>"upvote", "id"=>"6"}
I don't understand why my #vote do not appear in parameters...
Controller hacks_controller.rb
class HacksController < ApplicationController
skip_before_action :authenticate_user!, only: [:upvote]
def upvote
#vote = Vote.new(vote_params)
#hack = Hack.find(params[:id])
# raise
#vote.hack = #hack
if #vote.save
redirect_to root_path
else
p 'Problème de #vote.save !'
end
end
private
def vote_params
params.require(:vote).permit(:hack_id, :user_id)
end
end
Model Vote.rb
class Vote < ApplicationRecord
belongs_to :user
belongs_to :hack
validates :hack, presence: true
end
Thanks !
The Rails strong parameters are meant as mass assignment protection and are not suited to this case.
To create an additional CRUD method properly you can just add the additional route to resources:
resources :hacks do
post :upvote
delete :downvote
end
Note that we are using POST not GET as this is a non-idempotent operation.
You also don't need to pass any parameters. :hacks_id will be present in the path and you should fetch the current user id from the session and not the request parameters.
Passing a user id via the parameters is a really bad practice as its very trivial to spoof by using just the web inspector.
class HacksController < ApplicationController
before_action :set_hack!, except: [:new, :index, :create]
# POST /hacks/:hack_id/upvote
def upvote
#vote = #hack.votes.new(user: current_user)
if #vote.save
redirect_to #hack, success: 'Vote created'
else
redirect_to #hack, error: 'Vote could not be created'
end
end
# DELETE /hacks/:hack_id/downvote
def downvote
#vote = #hack.votes.where(user: current_user).first!
#vote.destroy
redirect_to #vote, success: 'Vote deleted'
end
private
# this will raise ActiveRecord::RecordNotFound if
# the id or hack_id param is not valid. This triggers a 404 response
def set_hack!
if params[:id].present?
Hack.find(params[:id])
else
Hack.find(params[:hack_id])
end
end
end
Then in your view you can create the links / buttons like so:
<% if current_user && #hack.votes.where(user: current_user) %>
<%= button_to 'Downvote', hack_downvote_path(#hack), method: :delete %>
<% else %>
<%= button_to 'Upvote', hack_upvote_path(#hack), method: :post %>
<% end %>
I have a very straight-forward task to fulfil --- just to be able to write comments under posts and if the comments fail validation display error messages on the page.
My comment model uses a gem called Acts_as_commentable_with_threading, which creates a comment model after I installed.
On my post page, the logic goes like this:
Posts#show => display post and a form to enter comments => after the comment is entered, redisplay the Post#show page which has the new comment if it passes validation, otherwise display the error messages above the form.
However with my current code I can't display error messages if the comment validation fails. I think it is because when I redisplay the page it builds a new comment so the old one was erased. But I don't know how to make it work.
My codes are like this:
Comment.rb:
class Comment < ActiveRecord::Base
include Humanizer
require_human_on :create
acts_as_nested_set :scope => [:commentable_id, :commentable_type]
validates :body, :presence => true
validates :first_name, :presence => true
validates :last_name, :presence => true
# NOTE: install the acts_as_votable plugin if you
# want user to vote on the quality of comments.
#acts_as_votable
belongs_to :commentable, :polymorphic => true
# NOTE: Comments belong to a user
belongs_to :user
# Helper class method that allows you to build a comment
# by passing a commentable object, a user (could be nil), and comment text
# example in readme
def self.build_from(obj, user_id, comment, first_name, last_name)
new \
:commentable => obj,
:body => comment,
:user_id => user_id,
:first_name => first_name,
:last_name => last_name
end
end
PostController.rb:
class PostsController < ApplicationController
before_action :authenticate_user!, except: [:index, :show]
def show
#post = Post.friendly.find(params[:id])
#new_comment = Comment.build_from(#post, nil, "", "", "")
end
end
CommentsController:
class CommentsController < ApplicationController
def create
#comment = build_comment(comment_params)
respond_to do |format|
if #comment.save
make_child_comment
format.html
format.json { redirect_to(:back, :notice => 'Comment was successfully added.')}
else
format.html
format.json { redirect_to(:back, :flash => {:error => #comment.errors}) }
end
end
end
private
def comment_params
params.require(:comment).permit(:user, :first_name, :last_name, :body, :commentable_id, :commentable_type, :comment_id,
:humanizer_answer, :humanizer_question_id)
end
def commentable_type
comment_params[:commentable_type]
end
def commentable_id
comment_params[:commentable_id]
end
def comment_id
comment_params[:comment_id]
end
def body
comment_params[:body]
end
def make_child_comment
return "" if comment_id.blank?
parent_comment = Comment.find comment_id
#comment.move_to_child_of(parent_comment)
end
def build_comment(comment_params)
if current_user.nil?
user_id = nil
first_name = comment_params[:first_name]
last_name = comment_params[:last_name]
else
user_id = current_user.id
first_name = current_user.first_name
last_name = current_user.last_name
end
commentable = commentable_type.constantize.find(commentable_id)
Comment.build_from(commentable, user_id, comment_params[:body],
first_name, last_name)
end
end
comments/form: (this is on the Posts#show page)
<%= form_for #new_comment do |f| %>
<% if #new_comment.errors.any? %>
<div id="errors">
<h2><%= pluralize(#new_comment.errors.count, "error") %> encountered, please check your input.</h2>
<ul>
<% #new_comment.errors.full_messages.each do |msg| %>
<li><%= msg %></li>
<% end %>
</ul>
</div>
<% end %>
<% end %>
I would instead use nested routes to create a more restful and less tangled setup:
concerns :commentable do
resources :comments, only: [:create]
end
resources :posts, concerns: :commentable
This will give you a route POST /posts/1/comments to create a comment.
In your controller the first thing you want to do is figure out what the parent of the comment is:
class CommentsController < ApplicationController
before_action :set_commentable
private
def set_commentable
if params[:post_id]
#commentable = Post.find(params[:post_id])
end
end
end
This means that we no longer need to pass the commentable as form parameters. Its also eliminates this unsafe construct:
commentable = commentable_type.constantize.find(commentable_id)
Where a malicous user could potentially pass any class name as commentable_type and you would let them find it in the DB... Never trust user input to the point where you use it to execute any kind of code!
With that we can start building our create action:
class CommentsController < ApplicationController
before_action :set_commentable
def create
#comment = #commentable.comments.new(comment_params) do |comment|
if current_user
comment.user = current_user
comment.first_name = current_user.first_name
comment.last_name = current_user.last_name
end
end
if #comment.save
respond_to do |format|
format.json { head :created, location: #comment }
format.html { redirect_to #commentable, success: 'Comment created' }
end
else
respond_to do |format|
format.html { render :new }
format.json { render json: #comment.errors, status: 422 }
end
end
end
private
# ...
def comment_params
params.require(:comment).permit(:first_name, :last_name, :body, :humanizer_answer, :humanizer_question_id)
end
end
In Rails when the user submits a form you do not redirect the user back to the form - instead you re-render the form and send it as a response.
While you could have your CommentsController render the show view of whatever the commentable is it will be quite brittle and may not even provide a good user experience since the user will see the top of the post they where commenting. Instead we would render app/views/comments/new.html.erb which should just contain the form.
Also pay attention to how we are responding. You should generally avoid using redirect_to :back since it relies on the client sending the HTTP_REFERRER header with the request. Many clients do not send this!
Instead use redirect_to #commentable or whatever resource you are creating.
In your original code you have totally mixed up JSON and HTML responses.
When responding with JSON you do not redirect or send flash messages.
If a JSON POST request is successful you would either:
Respond with HTTP 201 - CREATED and a location header which contains the url to the newly created resource. This is preferred when using SPA's like Ember or Angular.
Respond with HTTP 200 - OK and the resource as JSON in the response body. This is often done in legacy API's.
If it fails do to validations you should respond with 422 - Unprocessable Entity - usually the errors are rendered as JSON in the response body as well.
Added.
You can scrap your Comment.build_from method as well which does you no good at all and is very idiosyncratic Ruby.
class PostsController < ApplicationController
before_action :authenticate_user!, except: [:index, :show]
def show
#post = Post.friendly.find(params[:id])
#new_comment = #post.comments.new
end
end
Don't use line contiuation (\) syntax like that - use parens.
Don't:
new \
:commentable => obj,
:body => comment,
:user_id => user_id,
:first_name => first_name,
:last_name => last_name
Do:
new(
foo: a,
bar: b
)
Added 2
When using form_for with nested resources you pass it like this:
<%= form_for([commentable, comment]) do |f| %>
<% end %>
This will create the correct url for the action attribute and bind the form to the comment object. This uses locals to make it resuable so you would render the partial like so:
I'm assuming your form_for submits a POST request which triggers the HTML format in CommentsController#create:
def create
#comment = build_comment(comment_params)
respond_to do |format|
if #comment.save
make_child_comment
format.html
format.json { redirect_to(:back, :notice => 'Comment was successfully added.')}
else
format.html
format.json { redirect_to(:back, :flash => {:error => #comment.errors}) }
end
end
end
So, if #comment.save fails, and this is an HTML request, the #create method renders create.html. I think you want to render Posts#show instead.
Keep in mind that if validations fail on an object (Either by calling save/create, or validate/valid?), the #comment object will be populated with errors. In other words calling #comment.errors returns the relevant errors if validation fails. This is how your form is able to display the errors in #new_comment.errors.
For consistency, you'll need to rename #new_comment as #comment in the posts#show action, otherwise you'll get a NoMethodError on Nil::NilClass.
TL;DR: You're not rendering your form again with your failed #comment object if creation of that comment fails. Rename to #comment in posts, and render controller: :posts, action: :show if #comment.save fails from CommentsController#create
I have figured out the answer myself with the help of others here.
The reason is that I messed up with the JSON format and html format (typical noobie error)
To be able to display the errors using the code I need to change two places ( and change #comment to #new_comment as per #Anthony's advice).
1.
routes.rb:
resources :comments, defaults: { format: 'html' } # I set it as 'json' before
2.
CommentsController.rb:
def create
#new_comment = build_comment(comment_params)
respond_to do |format|
if #new_comment.save
make_child_comment
format.html { redirect_to(:back, :notice => 'Comment was successfully added.') }
else
commentable = commentable_type.constantize.find(commentable_id)
format.html { render template: 'posts/show', locals: {:#post => commentable} }
format.json { render json: #new_comment.errors }
end
end
end
I am trying to follow this rails tutorial but I am having a lot of issues due to version mismatches. I followed the instructions exactly and I really understand everything up until now but I can't seem to resolve this routing issue on my own. I read a good deal about routes independently but can't figure out what to do. This question has been posted once before on stackoverflow but that solution does not work for me because of version issues
Error Message:
No route matches [GET] "/book/list"
When trying to access http://localhost:3000/book/list.
Code
route.rb
Rails.application.routes.draw do
resources: :books
end
views>book>list.rhtml
<% if #books.blank? %>
<p>There are not any books currently in the system.</p>
<% else %>
<p>These are the current books in our system</p>
<ul id="books">
<% #books.each do |c| %>
<li><%= link_to c.title, {:action => 'show', :id => c.id} -%></li>
<% end %>
</ul>
<% end %>
<p><%= link_to "Add new Book", {:action => 'new' }%></p>
models>book.rb
class Book < ActiveRecord::Base
belongs_to :subject
validates_presence_of :title
validates_numericality_of :price, :message=>"Error Message"
end
models>subject.rb
class Subject < ActiveRecord::Base
has_many :books
end
controllers>book_controller.rb
class BookController < ApplicationController
def list
#books = Book.find(:all)
end
def show
#book = Book.find(params[:id])
end
def new
#book = Book.new
#subjects = Subject.find(:all)
end
def create
#book = Book.new(params[:book])
if #book.save
redirect_to :action => 'list'
else
#subjects = Subject.find(:all)
render :action => 'new'
end
end
def edit
#book = Book.find(params[:id])
#subjects = Subject.find(:all)
end
def update
#book = Book.find(params[:id])
if #book.update_attributes(params[:book])
redirect_to :action => 'show', :id => #book
else
#subjects = Subject.find(:all)
render :action => 'edit'
end
end
def delete
Book.find(params[:id]).destroy
redirect_to :action => 'list'
end
def show_subjects
#subject = Subject.find(params[:id])
end
end
There are a couple of issues I'm seeing. For one, your controller should be BooksController and not BookController (you'll also need to ensure it's in a file called books_controller.rb). Two, when you do resources :books, Rails will create the following routes
GET /books -> index
GET /books/:id -> show
GET /books/:id/edit -> edit
PUT /books/:id -> update
GET /books/new -> new
POST /books -> create
DELETE /books/:id -> destroy
As you can see, list is not one of the routes created, which is why you're getting that error message.
Extending #BartJedrocha's answer, first of all with your current routes i.e.
resources: :books
your application should not work and give you a Syntax error syntax error, unexpected ':', expecting keyword_end (SyntaxError).
As resources is a method invocation with argument :books.
So your route should be
resources :books ## Notice no : after "resources"
You have defined resources :books in your routes.So your controller Class name should be Plural ie., BooksController not BookController.So is the error.
Change your controller class name to BooksController and your filename to books_controller.rb
OR
update your routes to
resource :book #not singular
Note: I prefer the first way,because it suites the Rails convention
Update
You have to update your routes to like this
resources :books do
collection do
get 'list'
end
end
This will enable Rails to recognize the path /books/list with GET, and route to the list action of BooksController.
I have Project and ProjectSetting models with following associations:
class Project < ActiveRecord::Base
has_one :project_setting
end
class ProjectSetting < ActiveRecord::Base
belongs_to :project
end
In projects_controller I have:
def show
#project = Project.find(params[:id])
#project_setting = #project.project_setting
end
So I'm using #project_setting form in #project show page and I need to update #project_setting from this page.
In project_settings_controller I have:
def update
#project = Project.find(params[:id]) #problem is here
#project_setting = #project.project_setting
if #project_setting.update_attributes(params[:project_setting])
respond_to do |format|
format.html { redirect_to project_path(#project) }
format.js
end
end
end
But #project variables in these controllers aren't the same:
In projects_controller#show it is Project with ID 26 and in project_settings_controller#update it finds Project with ID 1
So I need to pass #project variable from projects_controller#show to project_settings_controller#update.
Thanks for any help!
In your show.html.erb you can pass the variables back to any controller. For example
<%= link_to "Update project setting",
:controller => "project_settings",
:action => "update",
:project => #project %>
will send the parameter "project" filled with the #project variable.
If you are in a form tag, you can send the variable with a hidden field tag:
<% hidden_field_tag("project", #project) %>
I hope, this helps.
params[:id] in project_settings_controller contained #project_setting.id
If you want to get #project.id from params, you should to write in routes.rb nested path:
resources :projects do
resources :project_settings
end
And then project.id is available in params[:project_id].
Example in rails_guides
How can you pass an error messages coming from a model --> controller to view?
= form_tag :controller => "article", :action => "create" do
/ how to retrieve error messages here?
%p
= label_tag :article, "Article"
= text_field_tag :article
= submit_tag "Submit Article"
I have this model:
class Article < ActiveRecord::Base
attr_accessible :article
validates :article, :presence => true
end
In my controller:
def create
#article = Article.new(params[:article])
if ! #article.save
# how to set errors messages?
end
end
I'm using Rails 3.0.9
The errors messages are stored in your model. You can access through the errors methods, like you can see in http://api.rubyonrails.org/classes/ActiveModel/Errors.html.
An easy way to expose the error message is including the follow line in your view:
%span= #article.errors[:article].first
But, I belive you have to change your controller to be like that:
def new
#article = Artile.new
end
def create
#article = Artile.new params[:article]
if !#article.save
render :action => :new
end
end
In the new action you don't need to try save the article, because the creation action already do that job. The new action exists, (basically) to call the new view and to provide support for validations messages.
The newmethod shouldn't save anything. create method should.
def create
#article = Article.new(params[:article])
if ! #article.save
redirect_to root_path, :error => "ops! something went wrong.."
end
end