I'm trying to learn Ruby on Rails, an I'm kinda stuck with associaton.
My project is to create a simple blog with three table. User, Post, and Comment.
In my understanding, after associationg several table with foreign key, rails would automatcily find user_id and post_id. But everytime I try to build comments, the user_id is nil.
Here's my model:
class User < ApplicationRecord
has_many :posts
has_many :comments
validates :name, presence: true, length: { minimum: 5 }, uniqueness: true
validates :password, presence: true, length: { minimum: 5 }
end
class Post < ApplicationRecord
belongs_to :user
has_many :comments
validates :title, presence: true
validates :body, presence: true, length: {minimum: 10}
end
class Comment < ApplicationRecord
belongs_to :post
belongs_to :user
validates :body, presence: true
validates :user_id, presence: true
validates :post_id, presence: true
end
Here is the screenshot when I try to create a comment:
As you can see, the post_id is not nil but the user_id is nil.
I try to input user_id manualy and it work as intended. But I can't find out how to create comment with automatic user_id and post_id.
In my understanding, after associationg several table with foreign key, rails would automatcily find user_id and post_id. But everytime I try to build comments, the user_id is nil.
There is no truth to that assumption. Rails will not automatically assign your assocations - how should it even know what user/post you want to associate the comment with?
Typically the way you would construct this is to have a nested route:
resources :posts do
resources :comments,
only: [:create]
shallow: true
end
This creates the route /posts/:post_id/comments so that we know which post the user wants to comment on - you would then adjust your forms so that it posts to the nested route:
# app/views/comments/_form.html.erb
<%= form_with(model: [post, comment]) do |f| %>
# ...
<% end %>
# app/views/posts/show.html.erb
# ....
<h2>Leave a comment</h2>
<%= render partial: 'comments/form',
locals: {
post: #post,
comment: #comment || #post.comments.new
}
%>
Getting the user who's commenting would typically be done by getting it from the session through your authentication system - in this example the authenticate_user! callback from Devise would authenticate the user and otherwise redirect to the sign in if no user is signed in.
You then simply assign the whitelisted parameters from the request body (from the form) and the user from the session:
class CommentsController
before_action :authenticate_user!
# POST /posts/1/comments
def create
# This gets the post from our nested route
#post = Post.find(params[:post_id])
#comment = #post.comments.new(comment_params) do |c|
c.user = current_user
end
if #comment.save
redirect_to #post,
status: :created
notice: 'Comment created'
else
render 'comments/show',
status: :unprocessable_entity,
notice: 'Could not create comment'
end
end
private
def comment_params
params.require(:comment)
.permit(:foo, :bar, :baz)
end
end
This is typically the part that Rails beginners struggle the most with in "Blorgh" tutorials as it introduces a resource thats "embedded" in another resource and its views and several advanced concepts. If you haven't already I read it would really recommend the Getting Started With Rails Guide.
you can create a comments as below:
user = User.find 2
post = user.posts.where(id: 2).first
comment = post.comments.build({comment_params}.merge(user_id: user.id))
Hope this will help you.
Related
I'm building an application where I have used nested attributes to store different option records under a question record. There is a form where the user can dynamically add and remove options. Everything works fine in my create action, but in the update action, if I remove an existing option and submit the form, it is not deleted from the database.
When updating the question record, is there any way to completely overwrite the existing nested parameters and replace it with the ones we pass in the update request?
I understand that adding _destroy to the attributes and passing it as a parameter would satisfy my requirement here. Since I'm deleting the option information from my frontend state on press of a "remove" button in the UI, I'm not sending it along with the params. Is there any other method in Rails to completely overwrite nested attributes and delete those nested records which are not passed in the update request, from the update action in the controller itself?
question.rb
class Question < ApplicationRecord
belongs_to :quiz
has_many :options
validates :body, presence: true
accepts_nested_attributes_for :options
end
option.rb
class Option < ApplicationRecord
belongs_to :question
validates :body, presence: true
validates :is_correct, inclusion: { in: [ true, false ], message: "must be true or false" }
end
questions_controller.rb
class QuestionsController < ApplicationController
...
def update
#question = Question.find_by(id: params[:id])
if #question.update(question_params)
render status: :ok, json: { notice: t("question.successfully_updated") }
else
render status: :unprocessable_entity, json: { error: #question.errors.full_messages.to_sentence }
end
end
...
private
def question_params
params.require(:question).permit(:body, :quiz_id, options_attributes: [:id, :body, :is_correct])
end
Relevant question
If I understand you correctly you're deleting the options one by one by clicking a button next to the option. Thats not actually something you need or want to use nested attributes for. Nested attributes is only relevant when you're creating/editing multiple records at once.
While you can destroy a single nested record by updating the parent:
patch '/questions/1', params: {
question: { options_attributes: [{ id: 1, _destroy: true }] }
}
Its very clunky and not really a good RESTful design.
Instead you can just setup a standard destroy action:
# config/routes.rb
resources :options, only: :destroy
<%= button_to 'Destroy option', option, method: :delete %>
class OptionsController < ApplicationController
# #todo authenticate the user and
# authorize that they should be allowed to destroy the option
# DELETE /options/1
def destroy
#option = Option.find(params[:id])
#option.destroy
respond_to do |format|
format.html { redirect_to #option.question, notice: 'Option destroyed' }
format.json { head :no_content }
end
end
end
This uses the correct HTTP verb (DELETE instead of PATCH) and clearly conveys what you're doing.
I can share my recent project work which is a bit similar to your where I am using shrine gem for upload images and I can update/destroy images which is associated with a Product model
product.rb
.
.
has_many :product_images, dependent: :destroy
accepts_nested_attributes_for :product_images, allow_destroy: true
product_image.rb
.
belongs_to :product
.
_form.html.erb for update
<%= f.hidden_field(:id, value: f.object.id) %>
<%= image_tag f.object.image_url unless f.object.image_url.nil? %>
<%= f.check_box :_destroy %>
and in products controller,I have whitelisted this
product_images_attributes: [:_destroy,:image, :id]
Hope this helps you to solve on your case
I have an app that has a blog feature. Originally when I set this up a post post consisted of a title, body, keywords, and image link. I want to be able to filter posts based on keywords and I think the cleanest way to do this is to move keyword to their own table and associate the two tables. So each posts can have multiple keywords and each keyword can have multiple posts.
I created a migrations and model for keywords.
class CreateKeywords < ActiveRecord::Migration[6.1]
def change
create_table :keywords do |t|
t.string :keyword
t.timestamps
end
end
end
class Keyword < ApplicationRecord
has_and_belongs_to_many :posts
end
I associated that with the posts table and changed the posts model.
class CreatePostsKeywordsJoinTable < ActiveRecord::Migration[6.1]
def change
create_join_table :posts, :keywords do |t|
t.index [:post_id, :keyword_id]
t.index [:keyword_id, :post_id]
end
end
end
class Post < ApplicationRecord
belongs_to :user
has_and_belongs_to_many :keywords
validates :title, presence: true
validates :body, presence: true
accepts_nested_attributes_for :keywords
# validates :keywords, presence: true
end
For now I just commented out the keywords in the Post model. I'm not exactly sure if I need to remove it or not. I already have existing posts that I don't want to lose as part of this switchover so I'm trying to keep that I mind as I figure out how to make this work. Where I'm really confused is what I need to change in the controller.
This is my Post Controller:
require 'pry'
class Api::V1::PostController < ApiController
before_action :authorize_user, except: [:index, :show]
# INDEX /post
def index
render json: Post.all, each_serializer: PostSerializer
end
# SHOW /post/1
def show
render json: Post.find(params[:id]), serializer: PostShowSerializer
end
# CREATE /post/new
def create
binding.pry
post = Post.new(post_params)
post.user = current_user
if post.save
render json: post
else
render json: { errors: post.errors.full_messages }
end
end
# UPDATE /post/update
def update
post = Post.find(params[:id])
if post.update(post_params)
render json: post
else
render json: { errors: post.errors.full_messages }
end
end
# DESTROY /post/destroy
def destroy
post = Post.find(params[:id])
if post.destroy
render json: {destroyed: true}
end
end
protected
def post_params
params.require(:post).permit([:title, :body, :image, :keywords])
end
def authorize_user
if !user_signed_in? || current_user.role != "admin"
redirect_to root_path
end
end
end
In the above state when I get to this part post = Post.new(post_params) I get an error saying NoMethodError (undefined method 'each' for "authorlife":String). If I remove keywords from the post_params I get this error Unpermitted parameter: :keywords
I feel like I am missing one or more steps here but it's been awhile since I've done anything with associated tables like this.
UPDATE:
Followed some of the advice below and I updated the above code to how it currently looks. Current issue is that when I check post_parms in the #create method I'm no longer receiving keywords at all. I checked the frontend and it's sending keywords. I'm assuming it's my post_params that's causing the problem. I've tried adding the keywords nested attribute like this but keywords still isn't showing up in the post_params
def post_params
params.require(:post).permit(:title, :body, :image, :keywords_attributes => [:id, :keyword])
end
This is the WIP for the code I'm trying to implement. I'm not sure what the keywords part is supposed to look like once I get the params situation figured out.
params = { post: {title: post_params["title"], body: post_params["body"], image: post_params["image"], keywords_attributes: [{ keyword: 'keyword title' },]
}}
In the above state when I get to this part post = Post.new(post_params) I get an error saying NoMethodError (undefined method 'each' for "authorlife":String). If I remove keywords from the post_params I get this error Unpermitted parameter: :keywords
You need to setup nested attributes for keywords if you want to update them through a post.
class Post < ApplicationRecord
belongs_to :user
has_and_belongs_to_many :keywords
validates :title, presence: true
validates :body, presence: true
accepts_nested_attributes_for :keywords
end
You can then pass in params structured like this in your controller
params = { post: {
title: 'title', body: "body", keywords_attributes: [
{ text: 'keyword title' },
]
}}
post = Post.create(params[:post])
https://api.rubyonrails.org/classes/ActiveRecord/NestedAttributes/ClassMethods.html
I already have existing posts that I don't want to lose as part of this switchover so I'm trying to keep that I mind as I figure out how to make this work.
It's good practice to remove this not used data anymore. You should write a data migration which moves the existing keywords from the posts table to the keywords table. Something like this
class KeywordsMigrator
def run
Post.all.each do |post|
keyword = Keyword.find_or_create_by(title: post.keyword)
post.keywords << keyword
end
end
end
Finally you can drop the keyword column from post.
You haven't really mentioned the current structure of the posts table so I assume you have a keyword column there. If you have a keywords column you have to name your association different until you remove the column otherwise you will run into troubles. For example you rename it to keywords_v1 and specify the class_name.
class Post < ApplicationRecord
belongs_to :user
has_and_belongs_to_many :keywords_v1, class_name: "Keyword"
validates :title, presence: true
validates :body, presence: true
end
Or you rename the column first to something like deprecated_keywords.
I just want to show the username who created the events. But when I try it says
undefined method `user_name' for nil:NilClass
This is my event.rb
class Event < ActiveRecord::Base
belongs_to :user
validates :name, presence: true
validates :description, presence: true, length: {minimum: 5}
end
And this is my user.rb
class User < ActiveRecord::Base
has_secure_password
has_many :events
end
And I am trying to show the user name in html.erb file like this.
<%= event.user.user_name %>
But I am getting this error.
So this is my create method in events_controller
def create
#event = current_user.events.new(event_params)
respond_to do |format|
if #event.save
format.html { redirect_to #event, notice: 'Event was successfully created.' }
else
format.html { render :new }
end
end
end
So what should I do for showing username in that page.
Thank You
Ok so here's the problem:
You want to show the event's user's name in index page but you can't be sure all events have one user associated with them. To avoid it you could use.
<%= event.user.try(:user_name) || 'No user associated' %>
Good luck!
Although the answer will get your app to work, it won't fix your problem.
The core issue is that your Event doesn't have an associated User object. This would not be a problem, except it seems from your code that you require an Event to have an associated User (current_user.events.new etc)...
You need the following:
#app/models/event.rb
class Event < ActiveRecord::Base
belongs_to :user
validates :user, presence: true #-> always makes sure user exists
delegate :user_name, to: :user #-> event.user_name
end
--
If you use the above code, you'll be able to call #event.user_name (solving the law of demeter with delegate). You'll also benefit from using validates presence to ensure the :user association exists on create & update.
This will allow you to rely on the #event.user object, which - to me - is far better than having to say "No user associated" in your app:
#view
<%= #event.user_name if #event.user %>
I want to make it so that users who log into my site can only like once on a question, But I would also want people who aren't logged in to also be able to like.
currently I have this to ensure that logged in users only vote once
model
class Yesvote < ActiveRecord::Base
belongs_to :user
belongs_to :question
validates_uniqueness_of :user, scope: :question
end
controller
def yesvote
#question = Question.find(params[:id])
if current_user != nil
yesvote = Yesvote.create(yes: params[:yes], user: current_user, question: #question)
else
yesvote = Yesvote.create(yes: params[:yes], question: #question)
end
if yesvote.valid?
redirect_to :back
else
flash[:danger] = "once only!"
redirect_to :back
end
end
currently if one user likes without logging in, it prevents further likes from un-logged in users. basically, it prevents more than one yesvotes to have a user_id of null/nil
This may helpful :-
validates_uniqueness_of :user_id, :allow_blank => true, :scope => [:question_id]
:allow_blank or :allow_nil, which will skip the validations on blank and nil fields, respectively.
To validate multiple attributes you could use scope:
class Yesvote < ActiveRecord::Base
belongs_to :user
belongs_to :question
validates_uniqueness_of :user_id, scope: :question_id
end
I guess you are using devise for authentication. If so, you can add a before filter in your controller to authenticate users before voting:
before_filter: authenticate_user!, only: :yesvote
def yesvote
#question = Question.find(params[:id])
yesvote = Yesvote.create(yes: params[:yes], user: current_user, question: #question)
redirect_to :back
end
Edit:
You can use Proc to skip validation if user_id is blank.
validates_uniqueness_of :user_id, scope: :question_id, unless: Proc.new { |v| v.user_id.blank? }
Im learning Rails and I'm just wondering if some code I wrote is correct and safe. I have two models, a user and post model. The posts belong to users, so I want to pass the user_id automatically to post when the object is created. I used an assign_attributes method in the post controller to set the user_id using the current_user helper provided by devise. Below is my relevant code. Again I want to know if this is correct or if there is better way of doing it.
def create
#post = Post.new(params[:post])
#post.assign_attributes({:user_id => current_user.id})
end
Post Model
class Post < ActiveRecord::Base
attr_accessible :content, :title, :user_id
validates :content, :title, :presence => true
belongs_to :user
end
User model
class User < ActiveRecord::Base
devise :database_authenticatable, :registerable,
:recoverable, :rememberable, :trackable, :validatable
# Setup accessible (or protected) attributes for your model
attr_accessible :email, :password, :password_confirmation, :remember_me
has_many :posts
end
You're pretty close. Since you've 1) been provided the current_user convenience helper by Devise, and 2) configured User and Post as a has_many/belongs_to relationship, it makes sense to create the new post, then append it to current_user. Then, in your Post model, you'll want to break up validations for individual attributes – the way you've listed :content, :title in sequence won't work.
# app/controllers/posts_controller.rb
def create
post = Post.create(params[:post])
current_user.posts << post
end
# app/models/post.rb
class Post < ActiveRecord::Base
attr_accessible :content, :title, :user_id
validates :content, :presence => true
validates :title, :presence => true
belongs_to :user
end
I don't think that is necessary since you have already created the relationship between posts and users. If you nest the posts resources into the user, it will automatically create the relationship between the 2 models.
In routes.rb
resources :users do
resources :posts
end
With that done, you will now reference posts as #user.post. I have already shown an example in this question.
I would say something like this :
def create
params[:post][:user_id] = current_user.id
#post = Post.new(params[:post])
#post.save
end
or
def create
#post = Post.new(params[:post])
#post.user = current_user
if #post.save
...
else
...
end
end
or
def create
#post = #post.new(params[:post])
#post.user_id = current_user.id
#post.save
end
You could put the user_id in the params but that would not be safe. user_id should not be in 'attr_accessable' so it will be protected for mass_assignment.