I am looking to build a simple set of calculators in a Rails 4 application and I am at a bit of a loss as to how I should go about setting up my models and controllers.
In this example I have a series of calculators that will have very similar but in some cases slightly different inputs / variables and slightly different calculation methods.
My first attempt was to simply create a Calculator controller without a model but quickly became lost as to where I would handle things like form params and calculation logic.
Creating a model also made little sense to me given that the calculators require some slightly different inputs and calculation methods.
Finally, creating multiple models also seemed like an extremely messy approach here in this scenario.
So with all of that in mind I was wondering if someone could show me the Rails way as to how I should approach this problem. If it helps to have further information I am looking to build out the same approach found in the following set of spreadsheets: http://www.widerfunnel.com/proof/roi-calculators
Any help would be seriously appreciated!
You should keep in mind that Rails is not only about MVC. You can create your custom classes, and use them in a model, or a controller.
In this case, you could create a Calculator class inside app/lib and use it inside your controller. For example:
# app/lib/calculator.rb
class Calculator
def self.sum(a, b)
a.to_i + b.to_i
end
def self.subtr(a, b)
a.to_i - b.to_i
end
end
.
# app/controllers/calculator_controller
class CalculatorController < ApplicationController
def index
end
def new
#result = Calculator.send(params[:operation], *[params[:a], params[:b]])
render :index
end
end
.
# app/views/calculator/index.html.erb
<%= form_for :calculator, url: { action: :new }, method: :get do |f| %>
<%= number_field_tag :a, params[:a] %>
<%= select_tag :operation, options_for_select([['+', :sum], ['-', :subtr]], params[:operation]) %>
<%= number_field_tag :b, params[:b] %>
<%= f.submit 'Calculate!' %>
<% end %>
<% unless #result.nil? %>
<p> = <%= #result %> </p>
<% end %>
This is just a very simple example on what is possible to do by creating your own classes and use them on Rails.
;)
Related
I have this logic currently in my view
<% tools_count = #job.tools.count - 1 %>
<% count = 0 %>
<% #job.tools.each do |u|%>
<%= u.name %>
<% if count != tools_count %>
<% count += 1 %>
<%= "," %>
<%end%>
<% end %>
Which just loops through some users relations and puts in a , unless it is the end of the list.
My question: This kind of logic looks really messy and clogs up my views I know there must be a better way of doing this by moving it into the controller or maybe model, does anyone know the correct way to do this kind of logic?
You can add a method like this to your Job model:
def tool_names
tools.map(&:name).join(',')
end
And use it in your view like this:
<%= #job.tool_names %>
There are couple of ways to avoid putting this kind of logic in the view layer:
Create an instance method in the model class (as spickermann suggested)
This will work for simple logic and simple projects. However, when you will want to use some helpers from ActionView::Helpers such as jobs_path or number_to_currency, a model is not a good place for it.
Create a helper method in helper modules eq. JobHelpers
Generally you can put any helper methods related to view layer in helpers. For example to share common methods for building a view components.
Use the decorator/presenter pattern and put there the view logic so model won't be polluted. Here is some more explanation about the pattern and sample implementation using draper gem: http://johnotander.com/rails/2014/03/07/decorators-on-rails/
You can do it in a single line like
<%= #job.tools.map(&:name).join(',') %>
So I've got two records from Model, a and b. I want to do this:
def do_codependant_stuff(a,b)
a.attribute += b.attribute2
b.attribute = b.stuff+a.stuff
end
I keep hearing fat model, skinny controller, and no business logic in views, so I've put this in my Model model. Based on what a user clicks in one of my views, I want to call do_codependant_stuff(a, b) or do_codependant_stuff(b,a).
I've been just using the basic crud controller actions up to this point, and I'm not quite sure how to make this happen. Do I add this logic to my ModelController update action? Because it's technically updating them, just in a more specific way. Or make another action in the controller? How do I call it/set it up? Most of the default new, update etc are somehow called behind the scenes based on their respective views.
And is updating two things at a time bad practice? Should I split the do_codependant_stuff method into two instance methods and call them on each record with the other as a parameter?
Thanks for reading.
Edit:
Alright, real world code. I'm displaying on the home page of my app two pictures. The user selects the one they like most. The ratings of these pictures change based on a chess ranking algorithm. This is the relevant section of my picture class.
class Picture < ActiveRecord::Base
...
...
def expected_first_beats_second(picture first, picture second)
1/(1+10**((second.rating-first.rating)/400))
end
def first_beat_second(picA,picB)
Ea = expected_first_beats_second(picA,picB)
picA.rating += 50*(1-Ea)
picB.rating += 50*(-(1-Ea))
end
end
The partial I'm using for the view just displays two pictures at random so far with
<% picA = Picture.offset(rand(Picture.count)).first %>
<% picB = Picture.offset(rand(Picture.count)).first %>
<div class = "row">
<div class = "col-md-5">
<%= image_tag picA.url, :class => "thumbnail" %>
</div>
<div class = "col-md-5">
<%= image_tag picB.url, :class => "thumbnail" %>
</div>
</div>
I need to somehow link the onclick of those images to the method in the model.
Here's some code to get you started. Note the comments, they're ruby and rails best practices
Controller:
class PC < AC
...
def compare
# count query once, save the number
count = Picture.count
#pic_a = Picture.offset(rand(count)).first
#pic_b = Picture.offset(rand(count)).first
end
def compare_submit
# Note variables are snake cased, not camel cased
pic_a = Picture.find(params[:winner_id])
pic_b = Picture.find(params[:loser_id])
pic_a.beats(pic_b)
redirect to compare_pictures_path # Or wherever
end
...
end
Any sort of querying should be done in the controller or model. You essentially should never directly access a model in your view. At this point your view has access to the instance variables set in the controller: #pic_a and #pic_b
View:
<%= link_to compare_submit_pictures_path(winner_id: #pic_a.id, loser_id: #pic_b.id) do %>
<%= image_tag #pic_a.url, :class => "thumbnail" %>
<% end %>
<%= link_to compare_submit_pictures_path(winner_id: #pic_b.id, loser_id: #pic_a.id) do %>
<%= image_tag #pic_b.url, :class => "thumbnail" %>
<% end %>
So we just linked to a new path (see routes below) that will pass two parameters: winner_id and loser_id so whichever picture the user clicks on you'll know which one they chose and which one they didn't choose.
Model:
class Picture < AR::Base
# Method arguments don't need a type declaration
def beats(loser)
# Always lowercase variables
ea = 1/(1+10**((loser.rating-self.rating)/400))
self.rating += 50*(1-ea)
loser.rating += 50*(-(1-ea))
self.save
loser.save
end
end
This explicitly uses self for clarity, which isn't necessary. Calling save or rating = ... implicitly calls it on self since we're in the context of an instance method on the picture Model.
Routes:
resource :pictures do
collection do
get :compare
get :compare_submit
end
end
First of all, I'm new to RoR, so the answer may be obvious, in which case I apologize. I've looked around and haven't found anything that helps.
I'm trying to have a search form at the header of every web page on my app that will search through the names of all my "buckets". Here is the relevant code:
In app/views/layouts/_header.html.erb (within a nav bar):
<% search_form_for #q do |f| %>
<%= f.label :name_cont %>
<%= f.text_field :name_cont %>
<%= f.submit %>
<% end %>
In app/controllers/buckets_controller.rb:
def index
unless params[:q].blank?
#q = Bucket.search(params[:q])
#buckets = #q.result.paginate(:page => params[:page])
else
#buckets = Bucket.find(:all, :limit => 5).paginate(:page => params[:page])
end
end
I understand the last part isn't that great: what I'm trying to do is if I'm just accessing the bucket index page (not by searching), i display the 5 most recently created buckets. When I search for something in the header form, I access the index page but only show the buckets that hit the search. (would a better way to handle it to have a search page separate from my index page?)
I found this issue which is pretty much identical, but I still don't see how I handle #q if every page is going to have the form on it--surely I don't have to alter every controller's every action?
Sorry in advance for any frustration my noobishness my cause you!
As others have said, you need to utilize the ApplicationController's before_filter. Though ernie himself seems not to recommend this, the implementation is simple.
First, use the advanced Ransack options to set your path for your search thusly
#config/routes.rb
resources :buckets do
collection do
match 'search' => 'buckets#search', via: [:get, :post], as: :search
end
end
Second, update your BucketsController to include the following custom action:
#controllers/buckets_controller.rb
def search
index
render :index
end
Nothing yet out of the ordinary. If you currently try to search you will get the error from your original question. Your definition of the variable q is correctly implemented, but you will have to move it to the ApplicationController like so:
#controllers/application_controller.rb
before_filter :set_global_search_variable
def set_global_search_variable
#q = Bucket.search(params[:q])
end
Finally, update your search form to pass in the correct search options
#layouts/_header.html.erb
<% search_form_for #q, url: search_buckets_path, html: { method: :post } do |f| %>
<%= f.label :name_cont %>
<%= f.text_field :name_cont %>
<%= f.submit %>
<% end %>
No, you do not need to edit all your controllers.
You can use ApplicationController for all your "common" controller needs. Read up on it in the guides http://guides.rubyonrails.org/action_controller_overview.html and the API docs http://api.rubyonrails.org/classes/ActionController/Base.html
The key here is, when you generated your new rails app, you'll notice it created the file .../app/controllers/action_controller.rb and that class derives from ActionController::Base. Then, if you again use the rails generator to create a controller for your app, you'll notice your new controller class derives from ApplicationController (not ::Base). That means that the application_controller.rb is the parent controller class for your app. That means everything in it is available to all your app controllers. It's easy to abuse, so be judicious.
Looks like this is not possible. This is a comment from Ernie the gem author.
You'd have to handle the Ransack-required stuff in a before_filter or
(ick) in the view partial itself. If you're putting a search field on
every single part of the site, I'd recommend you strongly consider
whether ransack is the right tool for the job, as well. You might want
some sort of inverted index search setup like sphinx, solr, etc.
https://github.com/ernie/ransack/issues/3
I'm trying to get the checkSwear method to run on each textfield before it's submitted..
I have basically this: (stripped down)
<%= form_for(#profile) do |f| %>
<div class="field">
<%= f.label 'I love to ' %>
<%= f.text_field :loveTo %>
</div>
<div class="field">
<%= f.label 'I hate to ' %>
<%= f.text_field :hateTo %>
</div>
<div class="actions">
<%= f.submit %>
</div>
<% end %>
In my controller I have:
def checkSwear
antiSwear.checkSwear(What goes here?)
end
In routes:
match '/check' => 'profiles#checkSwear'
Any help much appreciated!
(checkSwear is a separate gem; i.e. a separate problem! The what does here means what kind of variable is received from the form, to be put through the checkswear gem)
UPDATE:
Sorry for the camelcasing, I'm a Java developer studying Rails etc., old habits die hard. This is for a project. I'm supposed to be writing a small gem to do some ruby logic and apply it to something. The contents of the gem are:
module antiSwear
#swearwords = ["f**k", "f***ing", "shit", "shitting", "lecturer"]
#replacements = ["fornicate", "copulating", "poop", "pooping", "Jonathan"]
def self.checkText(text)
#swearwords.each do |swearword|
if text.include?(swearword)
index = #swearwords.index(swearword)
replacement = #replacements[index]
text.gsub(swearword, replacement)
end
end
return text
end
end
:/
This should really be done in model validations.
class Profile < ActiveRecord::Base
validate :deny_swearing
private
def deny_swearing
if AntiSwear.check_swear(love_to) || AntiSwear.check_swear(hate_to)
errors.add_to_base('Swearing is not allowed.')
end
end
end
That said, if you insist on this being in controller, you can check params[:profile][:love_to] and params[:profile][:hate_to] to see what's been submitted.
P.S. In this example I used proper ruby naming conventions, since we don't use "camelCasing".
Are you doing this as part of validation? You can do it one of a few ways. You can run the check before save, via a custom validation method or override the setter directly. I show you the custom validation approach here:
class Profile < ActiveRecord::Base
validate :clean_loveTo
protected
def clean_loveTo
errors.add(:loveTo, "can't contain swears") if antiSwear.checkSwear(loveTo)
end
end
I'm assuming checkSwear returns a boolean here.
I'd use an intersection on arrays, one of which is the source text split into words, then gsub the replacements in. You have to be sure to have a 1:1 relationship between the words and their replacements, in which case I'd suggest using a hash for your dictionary (coincidentally what hashes are sometimes called in other languages).
module antiSwear
# var names changed for formatting
#swears = ["f**k", "f***ing", "shit", "shitting", "lecturer"]
#cleans = ["fornicate", "copulating", "poop", "pooping", "Jonathan"]
def self.checkText(text)
# array intersection. "which elements do they have in common?"
bad = #swears & text.split # text.split = Array
# replace swear[n] with clean[n]
bad.each { |badword| text.gsub(/#{badword}/,#cleans[#swears.index(badword)] }
end
end
You might need to futz with text.split arguments if the replacement gets hung up on \n & \r stuff.
Hey all,(im a beginner in rails)
i've created a controller that look like that:
class HomeController < ApplicationController
def homepage
end
def showmsg
#postword = params[:p]
end
end
the showmsg view looks like that:
<%= #postword %>
and my homepage view looks like that:
<%= form_tag( {:controller => 'home', :action => 'showmsg'}, :method => "post") do %>
<%= text_field_tag(:p,#postword) %>
<%= submit_tag("post") %>
<% end %>
now i have a form that i can write something in it and it will show on the showmsg view.
i created a model with the param :posts with a :description "text" field too.
MY QUESTION is how do i implement the model in the code so any thing i write will be in a list with the things i wrote before, because now (obviously) anything if i write something its deleting the one i wrote before.
thank you all!
I would argue that you're approach is not very rail's like... so if you're learning rails... you're learning it wrong.
Make a Model. Call it "Message":
rails generate model Message content:string
remember to migrate (hopefully you have your databases setup properly):
rake db:migrate
Then in your controller, when you post, you can create message like this:
def create #instead of showmsg... 'create' is the standard name for this
Message.create(params[:message])
#messages = Message.all
end
This will create the message in the database, and then it will get all the messages out of the database and put them into #messages.
You need to edit your form so that it uses form_for. You need to pass it #message, which is an instance of Message.new that your first controller action created. You should call this new
In your create.erb.html file, you show all the messages like this:
<ul>
<% #messages.each do |message| %>
<li><%= message.content %></li>
<% end %>
</ul>
I actually wouldn't recommend showing all the messages in the create action - it should really happen in the index action and you should redirect... but we need to keep this simple. Just google this or watch some of Ryan's screencasts and you'll get it.
And you're done. This is the "Rails Way" to do things. It's best to learn it the way they want you to learn it.
I would also commend that you format your code properly by indenting, and start naming your methods to be real english. For example, showmsg is bad and show_message is a lot better.
If all of this is totally confusing, then just create a new project, and then type:
rails generate scaffold message content:string
It will basically build the application you want and a lot more. You can just read the code and see how they did it.
Hope it helps.
Your approach is not really rails like so some tweaks and fixes are needed. Suggestions: check rails approach to REST. The following code will work it is a little more rails like, but still not all the way there.
Generate a model
rails generate model Message postword:string
this will generate the model and create the migration necessary to create the table in the database.
Create the table
rake db:migrate
Define a post action
It will save the postword in the database. In your controller:
def create
#message = Message.create!(params[:message])
if #message.save
redirect_to "/home/showmsg"
else
render :action => "/home/homepage"
end
end
Create and instance of Message to use in your form
def homepage
#message = Message.new
end
Fix your form tag
<%= form_for #message, :url => "/home/create" do |f| %>
<%= f.label :postword %>
<%= f.text_field :postword %>
<%= f.submit "Create" %>
<% end %>
Now let's show the words in the showmsg page
In the controller select the postwords from the database:
def showmsg
#postwords = Message.all
end
Showing them: /showmsg.html.erb
<H1>postwords list</H1>
<ul>
<% #postwords.each do |p| %>
<li><%= p.postword %></li>
<% end %>
</ul>
Your routes.rb file will have this routes:
get "home/homepage"
get "home/showmsg"
post "home/create"
Define an attribute :new_text in a way similar to this:
class TheModel
# Virtual writer - everything assigned to this attribute
# will be added to self.text
#
def new_text=(v)
self.text += v.to_s
end
def new_text
"" # This is write-only attribute
end
end
Now, use the field 'new_text' in your form.
Of course, this is a very simple example. You should decide whether you want to add the content on every call to :new_text=, maybe some validation would help, the read accessor may need some care, and so on.
For some good guides which may help you start, see the site http://guides.rubyonrails.org/