Rails 3 Custom Method Location - ruby-on-rails

I am currently trying to add some parsing methods to a controller method in a Rails 3 application.
I have a controller action as follows:
def control
#device = Device.find(params[:id])
<do things>
parse_return(#returned_data)
end
and I added a custom method to the controller as below (this method would not have any routes and would only be accessible to controller actions):
def parse_return
<parse data>
end
but this does not appear to allow the parse_return method to be used. Is there somewhere else in the Rails app that I can put re-usable methods?
Thanks!

At a first glance it seems that you fail to render a response. Is it true that control action doesn't have an associated view?
In this case you have to manually call render in your action. For example, to render JSON response you can do this:
def control
# ...
render :json => parse_return(#returned_data),
:content_type => 'application/json',
:layout => false
end

You should include what the errors are.
What happens if you try this?
def parse_return(returned_data)
<parse data>
end
Perhaps the method is not expecting an parameter to be passed along with it.

Related

Set response status before render in rails 4

I'd like to set the response status value in particular action methods before the render method is called. Is this not possible?
Many of my methods in controllers render JSON API views for action methods like #destroy, #update, #create and those actions simply invoke #show or #index as is appropriate. However, I'd like to also return the appropriate HTTP Response status value, like 201, 202, etc, without having to pass arguments to these methods. Essentially, I am looking for something like this:
def destroy
# code that kills
status :accepted # ArgumentError, status= silently fails
index
end
if you just call
response.status = ###
in a controller, and then don't add the :status argument at render, it should get you what you need.
you can use the method render by passing the parameter :status, example :
render nothing: true, status: 201

Ruby on Rails controller design

When I look at examples of Rails controllers, I usually see something like this:
class WidgetController < ActionController::Base
def new
#widget = Widget.new
end
def create
#widget = Widget.new(params[:id])
if #widget.save
redirect_to #widget
else
render 'new'
end
end
end
This works, but there's a couple problems:
Routes
If I add widgets to my routes.rb file:
Example::Application.routes.draw do
resources :widgets
end
GET /widgets/new will route to new and POST /widgets will route to create.
If the user enters incorrect information on the new widget page and submits it, their browser will display a URL with /widgets, but the new template will be rendered. If the user bookmarks the page and returns later or refreshes the page, the index action will be called instead of the new action, which isn't what the user expects. If there's no index action or if the user doesn't have permission to view it, the response will be a 404.
Duplication of code
As a contrived example, let's say I had some tricky logic in my new method:
def new
#widget = Widget.new
do_something_tricky()
end
Using the current approach, I'd duplicate that logic in new and create. I could call new from create, but then I'd have to modify new to check if #widget is defined:
def new
#widget ||= Widget.new
do_something_tricky()
end
Plus, this feels wrong because it reduces the orthogonality of the controller actions.
What to do?
So what's the Rails way of resolving this problem? Should I redirect to new instead of rendering the new template? Should I call new inside of create? Should I just live with it? Is there a better way?
I don't think this is a problem in "the rails way" and there is no builtin functionality to allow this without getting your hands dirty. What does a user expects when bookmarking a form they just submitted and had errors? Users don't know better, and they shouldn't bookmark a failed form.
I think redirecting to new_widget_path is the cleanest solution. Yet, you should keep the errors and display them on the form. For this I recommend you keep the params in session (which I expect to be smaller than a serialized Widget object).
def new
#widget = widget_from_session || Widget.new
end
def widget_from_session
Widget.new(session.delete(:widget_params)) if session[:widget_params].present?
end
private :widget_from_session
# Before the redirect
session[:widget_params] = params
The code is self explanatory, Widget.new will only be called when widget_from_session returns nil, this is when session[:widget_params] is present. Calling delete on a hash will return de deleted value and delete it from the original hash.
UPDATE Option 2
What about submitting the form using ajax? Your controller could benefit from:
respond_to :html, :json
...
def create
#widget = Widget.new params[:widget]
#widget
respond_with #widget, location: nil
end
Based on the response code (which is set by Rails: 201 Created or 422 Unprocessable Entity), you could show the errors (available in the body of the response when validations fail) or redirect the user to #widget
This is how StackOverflow does it: https://stackoverflow.com/questions/ask. They submit the form asynchronously.
In general, I think the Rails way of solving the problem would be to put the tricky method onto the model or as a helper method, so the controller stays "thin" and you don't have to make sure to add custom behavior to both #new and #create.
EDIT: For further reading, I'd recommend the "Rails AntiPatterns" book, as they go through a lot of these common design issues and give potential solutions.
you put do_something_tricky() in its own method and call it inside the create action (but only when you're rendering the new template, ie when validation fails).
As for the bookmark issue, I don't know a good way to prevent that but to modify the routes and set the create action to the new action but using POST
get '/users/new' => 'users#new'
post '/users/new' => 'users#create'
UPDATE: using resources
resources :platos, except: :create do
post '/new' => 'plates#create', on: :collection, as: :create
end
then you can use create_platos_path in your forms
You don't need to write same function in two action , use before_filter instead.
If you want to have "widget_new_url" after incorrect submission then in your form add url of new widget path something like :url => widget_new_path .
Rails takes the url from Form .
I have this problem before, so I use edit action instead.
Here is my code.
Routes:
resources :wines do
collection do
get :create_wine, as: :create_wine
end
end
Controller:
def create_wine
#wine = Wine.find_uncomplete_or_create_without_validation(current_user)
redirect_to edit_wine_path(#wine)
end
def edit
#wine = Wine.find(params[:id])
end
def update
#wine = Wine.find(params[:id])
if #wine.update_attributes(params[:wine])
redirect_to #wine, notice: "#{#wine.name} updated"
else
render :edit
end
end
Model:
def self.find_uncomplete_or_create_without_validation(user)
wine = user.wines.uncomplete.first || self.create_without_validation(user)
end
def self.create_without_validation(user)
wine = user.wines.build
wine.save(validate: false)
wine
end
View:
= simple_form_for #wine, html: { class: 'form-horizontal' } do |f|
= f.input :complete, as: :hidden, input_html: { value: 'true' }
What I did is create a new action 'create_wine' with get action.
If user request 'create_wine', it will create a new wine without validation and redirect to edit action with a update form for attributes and a hidden field for compele .
If user has create before but gave up saving the wine it will return the last uncompleted wine.
Which means whether use save it or not, the url will be the same to /wines/:id.
Not really good for RESTful design, but solve my problem. If there is any better solution please let me know.

respond_with ArgumentError (Nil location provided. Can't build URI.):

I have a controller that responds_with JSON for all of the RESTful actions, index, create, update etc,
class QuestionsController
respond_to :json
def index
respond_with Question.all
end
end
However, I also have other actions in the controller. For example, in one method, it checks whether a response was correct and then tries to return a variable with a boolean true or false
respond_with correct_response #either true or false
However, this is giving me the error
ArgumentError (Nil location provided. Can't build URI.):
There will also be other methods that I'll wish to respond with multiple values. In Sinatra, you can do this to respond with json
{:word => session[:word], :correct_guess => correct_guess, :incorrect_guesses => session[:incorrect_guesses], :win => win}.to_json
How would I do that in Rails?
So, two questions, what's the proper way to write this
respond_with correct_response
and how to respond_with multiple values in a way similar to the example I showed from a Sinatra app.
Thanks for your help.
You want ActionController::Base#render, not respond_with. The proper way to do what you're trying to achieve here is:
render json: {word: session[:word], correct_guess: correct_guess, incorrect_guesses: session[:incorrect_guesses], win: win}
respond_with is actually OK for this scenario--it just happens to do some magic for you and relies on having access to info it needs; take a look at Rails 4.1.9's actionpack/lib/action_controller/metal/responder.rb.
In your case, ArgumentError (Nil location provided. Can't build URI.) is actually telling the truth--it's trying to determine a URL to use from the location header setting but isn't able to figure it out. I'd wager you could get your code working if you gave it one:
class QuestionsController
respond_to :json
def index
respond_with Question.all, location: questions_url
end
end

RSpec controller testing: missing template on create

I have an interesting situation. I am testing the following simple create action:
# will only be accessed via Ajax
def create
click = Click.new(params[:click])
click.save # don't really care whether its success or failure
end
Then I have the following very simple controller spec:
require 'spec_helper'
describe ClicksController, "creating a click" do
it "should create a click for event" do
xhr :post, :create, :click => {:event_id => 1}
# more test to come...
end
end
Seems trivial, yet I get the following:
Missing template clicks/create
Any tips would be appreciated.
Add to the controller action:
render :nothing => true
This one will automatically create the appropriate server's respone. More here
You will get this error if your controller renders only JSON or XML, yet you don't specify a format in the spec; your request then defaults to unsupported HTML. In that case, simply specify the supported format when you invoke the controller method from your spec. For example, change this:
post :create, registration: #user_hash
to this:
post :create, registration: #user_hash, format: :json
If you do not render anything in a controller action, rails will attempt to default to rendering a template (in this case clicks/create). I'd suggest rendering back at least a success message like so:
render :json => {:success => true}
Building on megas's answer, if you're looking to test a controller action that's only accessed via a UJS link and only has a .js.erb template, I'd put this in the controller to avoid breaking your UJS functionality:
respond_to do |f|
f.html { render nothing: true } # prevents rendering a nonexistent template file
f.js # still renders the JavaScript template
end
This will enable you to call the controller action by simply calling ActionController::TestCase::Behavior's get/post/put/delete methods instead of needing to call xhr, because it will successfully call the method, render nothing, and continue on, while leaving your UJS behavior intact.

Rails - Controller Action can only be executed by JS call

In my view file, I use a collection_select with an :onchange => remote_function that execute another action from the same controller (the action will eventually update the page content)
I'd like this action to be only accessible when called by the JS but not when the corresponding route is directly entered as an URL in the browser.
Any idea how I could do this ?
You can use request.xhr? to check the request type, either its AJAX request or others (post, get). It returns true or false. If true you can perform the action.
You could use respond_with and respond_to
class MyController
respond_to :js
def index
respond_with(#users = User.all)
end
end

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