I was hoping someone could help me with this, been trying to figure it out for a week now, I found a lot of examples, but as I'm new to rails I guess I keep making a mistake somewhere and I just cant find a right solution for my case.
So I have:
class Blog < ActiveRecord::Base
attr_accessible :name, :subject_id, :created_at
has_many :blogs_messages
has_many :messages, through: :blogs_messages
end
class Message < ActiveRecord::Base
attr_accessible :title, :body, :created_at
has_many :blogs_messages
has_many :blogs, through: :blogs_messages
end
class BlogsMessages < ActiveRecord::Base
attr_accessible :message_id, :blog_id
belongs_to :blog
belongs_to :message
end
Messages live in different Blogs(like Pink Blog, Green Blog, Maroon Blog etc), and Blogs live in Subjects (Dark Colors, Bright Colors etc)
Subjects have many Blogs, but Blogs can belong only to one Subject.
BlogsMessages is the connection between Messages and Blogs
what im trying to do is to show:
top 3 Blogs (by amount of messages in them) within one Subject
so e.g. when I want to choose Subject Dark Colors it will show me:
1.Maroon Blog: 46 messages
2.Grey Blog: 13 messages
3.Purple Blog: 12 messages
(There are 8 Blogs altogether in Subject Dark Colors.)
Could someone please help me with this, or at least point me in the right direction how to make it all work?
Update:
in my Blogs_controller now i have:
#blogs = Blog.joins(:blogs_messages => :message).select('blogs.*, COUNT(messages.id) AS message_count').group('blog_id').order('COUNT(messages.id) DESC').limit(3)
in my blogs view:
<% #blogs.each do |blog| %>
<li><%= blog.name %>: messages</li>
<% end %>
I'm not sure this can work because I can't test it but it may help you:
Blog.where(subject_id: subject.id)
.joins(:blogs_messages => :message)
.select('blogs.*, COUNT(messages.id) AS message_count')
.group(:blog_id)
.order('message_count DESC')
.limit(3)
Also, in the view you could access to the new virtual attribute message_count:
<% #blogs.each do |blog| %>
<li><%= blog.name %>: <%= blog.message_count %> messages</li>
<% end %>
Related
I have a question. I have two tables with an NN relationship. They are perfectly well linked in base (verified by the console with a Tips.find(1).categories). The two tables are Tip and Category. My objective is to create a search form that allows you to select a category, and to display all the Tip related to that category. I found a method that does this, it works for base links (i. e. if for example there was a category_id in the Tip table, which is not the case here). So I have to find a way to write the following search condition:
Tip.rb
class Tip < ApplicationRecord
has_many :category_to_tips
has_many :categories, through: :category_to_tips
has_many :comments
belongs_to :creator, class_name: "User"
has_many :likes, dependent: :destroy
def self.search(params)
tips = Tip.where("(tips) LIKE ?", "%#{params[:search]}%") if params[:search].present?
tips
end
end
Tip_controller :
def index
#tip = Tip.all
#tip = Tip.joins(:categories).search(params[:search])
end
form in index.html.erb :
<%= form_tag tips_path, :method => 'get' do %>
<p>
<%= text_field_tag :search, params[:search] %>
<%= submit_tag "Search", :name => nil %>
</p>
<% end %>
And when I run my form, i have this error :
PG::SyntaxError: ERREUR: erreur de syntaxe sur ou près de « . »
LINE 1: ...ry_to_tips"."category_id" WHERE ((Category.find(2).tips) LIK...
^
: SELECT "tips".* FROM "tips" INNER JOIN "category_to_tips" ON "category_to_tips"."tip_id" = "tips"."id" INNER JOIN "categories" ON "categories"."id" = "category_to_tips"."category_id" WHERE ((Category.find(2).tips) LIKE '%2%')
I hope I've been clear and I thank you in advance! :)
If I am reading it correct you are looking for a category so that you can display all the tips related to the category. Why don't you just do this in youre controller.
#tip = Category.where("name LIKE ?", "#{params[:search]}%").includes(:tips).map(&:tips).uniq
name would be the database field from category you are searching on.
I am working on a rails app that registers campers for a camp. First you sign up using your name, email, etc. Once your profile is made, you can register for a camp. If the camp is not already full, then you are immediately enrolled. If it is full, then you are put on a waitlist. Right now I have 4 models: Campers (name, email, etc.), Camps (name, location, etc.), Enrollments, and Waitlists.
The idea is to have a camper be able to register to many camps, and obviously a camp having many campers enrolled or waitlisted in it. Here are my classes:
# camper.rb
has_many :enrolled_in, :class_name => 'Camps', through: :enrollments, dependent: :destroy
has_many :waitlisted_in, :class_name => 'Camps', through: :waitlists, dependent: :destroy
# camp.rb
has_many :enrolled_campers, :class_name => 'Camper', through: :enrollments
has_many :waitlisted_campers, :class_name => 'Camper', through: :waitlists
I'm having trouble with accessing these models through the views. Here is what show.html.erb looks like:
<!-- Listing camps -->
<h2>Camps</h2>
<p>
<strong>Name:</strong>
<%= #camper.enrolled_in.name %> <!-- This is where I get the error -->
</p>
<!-- Adding camps -->
<h2>Add a camp:</h2>
<%= form_with(model: [#camper, #camper.enrolled_in.build ]) do |form| %>
<p>
<%= form.label :name %><br>
<%= form.text_field :name %>
</p>
<p>
<%= form.submit %>
</p>
<% end %>
But I'm getting the following error:
ActiveRecord::HasManyThroughSourceAssociationNotFoundError in Campers#show
Could not find the source association(s) "enrolled_in" or :enrolled_in in model Enrollment. Try 'has_many :enrolled_in, :through => :enrollments, :source => '. Is it one of camp or camper?
And I honestly can't tell what's going wrong. I'm fairly new to databases and rails, so go easy on me.
Look to direction of HABTM associations.
This will make your code cleaner.
You will have :after_add and :after_destroy actions that will always track model changes (even direct foreign key inserting, unlike in same named has_many callbacks.)
So.
class Camper
has_and_belongs_to_many :waitlists, after_add: :check_camp_ready_to_start_as_example
has_and_belongs_to_many :enrolllists
end
class Waitlist
belongs_to :camp
has_and_belongs_to_many :campers
end
class Enrolllist
belongs_to :camp
has_and_belongs_to_many :campers
end
class Campl
has_many :enrolllists
has_many :waitlists
end
How to create such migrations (need to create join tables), you can read here
I'm a new guy to ruby on rails and working on my first in-depth application. It has four tables: Questions, Options, Answers and Users. There's a list of questions and a user can vote for a unique option (stored in the Answers join table), I'm trying to get my head around table associations.
This is how I've setup my individual RB files:
class Question < ActiveRecord::Base
has_many :options
has_many :answers, :through => :options
end
class Option < ActiveRecord::Base
belongs_to :question
has_many :answers
end
class Answer < ActiveRecord::Base
belongs_to :user
belongs_to :question
belongs_to :option
end
class User < ActiveRecord::Base
has_many :answers
has_many :questions, :through => :answers
end
My questions controller is setup like this to include the options table:
#questions = Question.includes(:options).all
and the table body in my index.html.erb file:
<tbody>
<% #questions.each do |question| %>
<tr class="<%= cycle('lineOdd', 'lineEven') %>">
<td><%= question.question_text %></td>
<td><%= link_to 'Show', question %></td>
<td><%= link_to 'Edit', edit_question_path(question) %></td>
<td><%= link_to 'Destroy', question, method: :delete, data: { confirm: 'Are you sure?' } %></td>
</tr>
<% question.options.each do |option_text| %>
<tr class="backgroundColor1">
<td class="optionCell"> <%= option_text.option_text %> </td>
</tr>
<% end %>
<% end %>
</tbody>
In the Question class I've used 'has_many :answers, :through => :options' - is this the correct way to go about this and how would I output the total number of votes in a table row below the associated option.
Do I need to add to or change the question controller code?
This is my first post, sorry if I'm not informative enough!
Thanks
Lets start by fixing up the relations a bit:
class Question < ActiveRecord::Base
has_many :options
has_many :answers
has_many :users, through: :answers
end
There is nothing technically wrong with has_many :answers, :through => :options but since there is a direct relation through answers.question_id we don't need to go through the options table for the relation.
Displaying the count
If we simply did:
<td class="optionCell"><%= option.answers.count %></td>
This would create a nasty n+1 query to fetch the count of the answers for each option. So what we want to do is create a counter cache which stores a tally on the options table.
Lets start by creating a migration to add the column:
rails g migration AddAnswerCounterCacheToOptions answers_count:integer
rake db:migrate
Then we tell ActiveRecord to update the tally when we create associated records, this looks a bit strange since the counter_cache: true declaration is on the belongs_to side while the column is on the other but thats just how AR works.
class Option < ActiveRecord::Base
belongs_to :question
has_many :answers
end
class Answer < ActiveRecord::Base
belongs_to :user
belongs_to :question
belongs_to :option, counter_cache: true
end
There is a little snag here. Since we may already have records we need to make sure they have correct counters. You can do this from the console but in the long run it is a good idea to create a rake task.
Option.find_each { |option| Option.reset_counters(option.id, :answers) }
This might take a bit of time since it needs to pull each Option and update the count.
Now we can display the tally like so:
<% question.options.each do |option| %>
<tr class="backgroundColor1">
<td class="optionCell"><%= option.option_text %></td>
<td class="optionCell"><%= option.answers.size %></td>
</tr>
<% end %>
.size is smart enough to use our counter cache column, but will fall back to querying the count which is a good thing for tests.
I have a form where there can be three select boxes depending upon a checkbox - I'm using jQuery to show/hide them depending on which checkbox is active. Below, f is player
<% Game.all.each_with_index do |game, i| %>
<div class="team_<%= i %> hide">
<%= f.collection_select(:team_division_id, TeamDivision.where("game_id = ?", game.id),
:id, :name, include_blank: true) %>
</div>
<% end %>
Each collection select is generating an id of player_team_division_id - and since there can be only one id a page, this is really screwing with my results, namely the first select box shows up fine, but the others show up as simple links to javascript:void(0) - if I check out the generated divs with firebug/chrome, the information is there, it just isn't showing up as a select box (presumably) because of the id. I'm using chosen.js, if that makes a difference, although I'm don't think this has any affect.
Edit (Models):
class Player < ActiveRecord::Base
belongs_to :game
belongs_to :team_division, touch: true
end
class Game < ActiveRecord::Base
has_many :players
has_many :team_divisions
end
Class TeamDivision < ActiveRecord::Base
has_many :players
belongs_to :game
end
Im stuck (still very new to Rails), and cant figure out why its not working:
I have:
class Message < ActiveRecord::Base
attr_accessible :updated_at
has_many :categories_messages
has_many :categories, through: :categories_messages
end
class CategoriesMessage < ActiveRecord::Base
attr_accessible :category_id, :message_id
belongs_to :category
belongs_to :message
end
class Category < ActiveRecord::Base
attr_accessible :name
has_many :categories_messages
has_many :message, through: :categories_messages
end
#messagesPer = Category.all.includes(:messages).group('categories.id').order("COUNT(messages.id) DESC")
<% #messagesPer.each_with_index do |message, i| %>
<tr>
<td><%= i+1 %></td>
<td><%= message.name %></td>
<% if message.categories_messages.exists? %>
<td><%= message.messages.last.updated_at.to_s.to_date %></td>
<td><%= message.messages.first.updated_at.to_s.to_date %></td>
<td><%= message.messages.count %></td>
<% else %>
<td>0</td>
<td>0</td>
<% end %>
</tr>
<% end %>
So i want it to show :
the name of Category, date the last message was created , date first message was created, and all messages in that category.
ALl works fine, apart from the fact that it only shows the date when the first message was created, but never the last (still shows first date on the last).
What am i doing wrong?
UPDATE:
if i put
#messagesPer = Category.all.includes(:messages).group('categories.id')
it does show the right date for last and first messages but as soon as i add order it breaks...
I might be helpful to include the error information you get after adding an order clause to the query.
However, I can spot some odd things in the code. The CategoriesMessage model seems to be there simply to satisfy the condition that a category can have many messages and vice versa. You don't need a model for this many-to-many relationship though, Rails will handle this automatically for you.
Your models should be looking like this:
class Message < ActiveRecord::Base
attr_accessible :updated_at
has_and_belongs_to_many :categories
end
class Category < ActiveRecord::Base
attr_accessible :name
has_and_belongs_to_many :messages
end
And in your database you have these tables: messages, categories,categories_messages, where the last one is the join table which only contains columns for amessage_idand acategory_id`.
Then you can simply do something like this in your code:
category.messages.each { |message| puts message.updated_at }
Also see this Ruby on Rails tutorial article for more information. If this doesn't work for you, please post the exact error you get.