I need to have two (or maybe even more) different create (and update) methods in one controller. I already have views displaying the forms, so I basicaly only need to tell the submit which method to call in the controller. Is that possible? If so, how? Or can I only have one create method and have that method do different things depending on which view called the method?
Thanks
Ignoring the fact that this sounds like a really terrible idea, it's possible. You will need to add some more routes that will match the new actions in your controller. You won't be able to call them 'create' and 'update' because method names must be unique within the same class.
Having said that, I really beg you to rethink your approach. REST, as described in the Rails Getting Started guide, by far the standard for building Rails applications. If you're not familiar with it, I would recommend stopping where you are and reading up on it. Your application will be much easier to build and maintain, and you won't waste time asking structural questions. If you are familiar with it and are choosing to ignore it, then I wish you the best of luck.
you can use this command:
rails g scaffold_controller 'controller_name'
or if spastic method you can use this:
rails generate controller 'controller_name' add new
Let's say that you have an object Book. You can change values of Book in any method inside of your books_controller.rb as long as that method has access to #book.id.
def crazy_create_method
book.create (book_params)
book.save
end
That being said, try to stick to the default new/create methods and if you need to get weird later on it's always easy to call the code belong in whatever method you need. Rails bakes a lot of out of the box functionality into the default REST actions.
book.title = my_title
book.save
Related
I'm in the process of updating a website I made almost 2 years ago. It was my first real website and I made some mistakes (some more serious that others).
What apparently is one of my biggest is making database calls from the view.
I'm pretty damn sure there is a better way to do this:
Use Case:
Someone fills out a form for a new subject, populating the Subject table, and they have been marked "enrolled", Subject.enrolled = 1
Based on that, I now need to create a record in 5 other tables (such as Baseline)
Downhill from here, here is my method
Determine if the record exist based on subject_id from Subject (sub)
<$ if Baseline.where(subject_id: sub.subject_id).first != nil $>
If it does not exist, create the record, (otherwise display the link)
<%= Baseline.create(subject_id: sub.subject_id) %>
This all happens in the view, and creates a front-end table with links to each record in the process. So I'm creating records based on for-loop logic...
Question:
So I'm looking for direction. I don't want to guess how to do this - I'm pretty sure the model/controller should do this - I want to learn how to do it correctly. How do I create records automatically, based on a value in a table?
Thank you for your time.
Not quite sure how your domain and code looks like, but to answer this question: 'How do I create records automatically, based on a value in a table?', it seems that you could use ActiveRecord callbacks, like this:
class Subject < ActiveRecord::Base
after_commit :create_baseline_if_enrolled, on: [:create, :update]
private
def create_baseline_if_enrolled
return unless enrolled?
# enrolled? == true, you may create these models here
end
end
To answer your question:
It depends :) This is just one possible solution. Another one would be to put such a custom logic in your SubjectsController and call it directly from the #create, #update methods. Both approaches have pros and cons. For example, abusing callbacks (anywhere) makes code less readable and harder to debug. On the other hand, putting such logic in controllers puts a burden on you that you have to remember about calling it if you happen to be editing subjects in other places (but is more explicit). Whichever way you choose, remember not to make your classes too fat, for example try to use service object pattern to separate such custom logic as soon as you feel like it is getting out of hand. :) And don't forget about tests - when things go wrong, tests make refactoring easier.
In case you were unaware, this is a beginner's question.
Having learned a bit of Ruby, I have ventured onto Rails, but have run into a brick wall when it comes to organizing methods. I'm building something which is supposed to take the data/parameters you get when someone creates something, but instead of showing it like you would a tweet or blog post, I want to use them as variables in some mathematical calculations, the results of which I then want to show.
Now, in Ruby, I would make a method for each little math operation, to make sure they (the methods) have a single responsibility each. In Rails, though, what am I supposed to do? In case you don't understand my problem, I think it has to do with my lack of understanding of instances in Rails. Instances in Ruby can call upon the methods I make, but where do I call upon my methods (actions?) in Rails?
You should follow the MVC paradigm:
The controller should receive the parameters that the user gave via some html form.
Then that controller should instantiate an object that is doing the math calculation and then the controller should render a view to present the results to the user.
The place where the controller and the views are stored is already decided by the framework:
controllers are in app/controllers and the views in app/views/<controller_name>
Now the question is where you put the class that performs the calculations.
You might think about the app/models folder, but that one is typically for the models that inherit from ActiveRecord::Base, ie, all those that are persisted in the database.
Normally the kind of class that you are implementing lives in the lib folder.
For example, you might have the following structure:
app/controllers/calculations_controller.rb
def perform_calculations
math_calculator = MathCalculator.new params[:operation]
#result = math_calculator.calculate
end
lib/math_calculator.rb
class MathCalculator
def calculate
# whatever you need to do here
end
end
app/views/calculations/perform_calculations.html.erb
<%= #result %>
There's nothing official, I think its helping you
http://www.caliban.org/ruby/rubyguide.shtml
I'm using Rails 4. I have a class, Cart, which needs to be accessed within my application.
I want it accessed using the factory pattern:
class CartFactory
def self.obtain_cart_for_user(user)
...
end
end
I need this approach because sometimes, I want to return an existing cart and sometimes create a new one (based upon the age of the cart, its contents, whether the products in it are still available etc).
This is easy enough.
However, I also want to make sure some other future programmer doesn't instantiate a cart directly, or fetch one by any other means, including via model associations, such as:
Cart.new(...)
user.carts.new(...)
Cart.find(id)
Cart.find_by_attribute(blah: blah)
Cart.where(...).first
Is there any way to prevent that?
Well, it's possible to make the constructor private:
private_class_method :new
And of course, you can try making the ActiveRecord query methods (.find, .where etc.) private as well. But to me that sounds like a good way to end up with erratic behaviour. If you were to go this route, make sure your app is thoroughly tested first.
Another route would be for Cart not to extend ActiveRecord::Base (which I'm assuming it does), and instead include only the parts you need, like ActiveRecord::Persistence. If you are willing to dive in deep, check out the parts that are included in the source for ActiveRecord::Base.
Edit: Still one option would be to make Cart itself private within a module that only exposes CartFactory. There's no built-in syntax for a "private class", but it's possible to achieve since Ruby classes are just regular objects. Again, no idea how well ActiveRecord would deal with that.
But lastly there is of course the question of whether you want to do this at all. In general, Ruby is not very good at protecting you from yourself. :) As expressed in the latter linked answer, documentation and trust go a long way.
Consider I have a controller with an action which renders a view. The view needs data to render. I know the following ways to prepare and send it to the view:
Using instance variables
class CitiesController < ApplicationController
def index
#cities = Cities.order(:name).limit(10)
end
end
This is the default approach which can be found in Rails documentation, but it has some disadvantages:
It makes the action code fat which becomes responsible not only for controller logic, but also for the data preparation.
Views need to access this data through instance variables – those #-variables break the principle of least astonishment.
Using helper methods
class CitiesController < ApplicationController
helper_method :cities
def index
end
def cities
#cities ||= Cities.order(:name).limit(10)
end
end
That's the way I prefer the most. It keeps action methods clean, so I may implement controller logic there not mixing it with data preparations in one method. Also, there's no need to use mysterious instance variables in views, making them isolated. However:
The data preparations are still in the controller. It becomes unreadable when there are a lot of these helper methods, especially when they are relative to different actions/views.
There's a need of having a unique name for each helper method. Say, I can't have a method called products which will return different data for different actions (of course, I can do it in one method, but it would look ugly).
Using the facade pattern
Partially the problem is solved in this article: https://medium.com/p/d65b86cdb5b1
But I didn't like this approach because it introduces a #magic_facade_object in views.
Using inherited resources
It may look beautiful in examples, but in my opinion when it comes to the real code, controller code becomes a spaghetti-monster very fast. The other thing is that a page view usually needs not only the resource but also other data to render (sidebar blocks, etc.) and I still have to use another way to prepare it. Combining different approaches makes the code even more unreadable. Finally, I don't like to use resource variable, because it makes not very clear what is the view about.
So, here is the question. How do you keep your controllers clean?
How do you keep your controllers clean?
By writing DRY code and sprinkling some gem magic around.
Having a look at your bullet points, I think I have a different opinion on most of the stuff.
#cities = Cities.order(:name).limit(10) is exactly what i think belongs into a rails controller and it does not violate the principle of least surprise, it's kind of the opposite. instance variables are the default way of passing around variables from controllers to views, even though that is a pretty ugly thing to do. it's "the rails way" (TM)!
decent_exposure takes away most of these concerns
please stop applying old-school pattern to rails or ruby code. it's really just useful in large applications where you are struggling to keep sane with the amount of code that's within a single controller method. write clean code, test it thoroughly and you will be fine 80% of the time.
don't use "one size fits all" tools. most often, you need to write more configuration than you would need code to make it work. it's also getting a lot more complex through this kind of things.
I'm building a model, which whenever the model is run I want to inject into a news feed model. My idea was to create a after_save in the model and then use a helper to populate the feed details. But my model isn't finding the helper...
Now I'm wondering, what are helpers for, are helpers really just for Views or?
In my model I want to run stuff like:
newsfeed.feeded_id = record.id
newsfeed.feeded_type = record.class.name
Which is common to many models in my app. Where should that live, and how should that be accessed? Thanks
Helpers are primarily for views. They allow you to keep your code out of the views and make a testable chunk of code that can be used when rendering the view. It also allows you to reuse bits of code.
I don't think there are any rules of thumb, but if you use the exact same bit of view code more than once, consider abstracting it into a partial. If you have any complicated conditionals or calculations, consider placing it in a helper.
As an example of what's good to put in helpers, you need look no further than Rails itself. Perfect examples are link_to, form_for, etc. These take a bit of doing to construct but provide way more functionality than writing the HTML from scratch each time.
How about using an observer?
Are you setting up your news via RSS/ATOM? Your builder view might be a place to select what items you want in your feed.