I am very new to rails and following a tutorial for RESTful API so let me excuse if it is of not very good quality as I am equally a starter for these kind of terminologies as well.
I created a controller kitten with a command rails g controller kitten index
and in the index method I posted this code -
class KittenController < ApplicationController
def index
require 'open-uri'
kittens = open('http://placekitten.com/')
response_status = kittens.status
response_body = kittens.read[559, 441]
puts response_status
puts response_body
end
end
and un commented match ':controller(/:action(/:id))(.:format)' in routes.rb
When i navigate through this - http://localhost:3000/kitten
this is what i am getting in my browser -
Kitten#index
Find me in app/views/kitten/index.html.erb
and this in my command line -->
Now my question why it so although i am expecting it in my browser but the cat is shown in command prompt instead of browser ..i am new to rest resource so please excuse if it is a bad one :(
I don't know what tutorial you're following, but doing this seems like a very odd thing to do for Rails in general and learning RESTful APIs in particular.
Anyway, the puts in your controller outputs text to Ruby's standard out, which is going to be the terminal where the server started. That's why this is appearing in the console rather than in your browser: puts is putting it there.
If you want this to appear in a web page, you'll need to make a view for that controller action. Perhaps following further along your tutorial will get you there: if not, you might want to find a better one.
You should read the Model-View-Controller rails guide.
Controllers provide the “glue” between models and views. In Rails, controllers are responsible for processing the incoming requests from the web browser, interrogating the models for data, and passing that data on to the views for presentation.
Define your variable in the controller and display it in the view:
class KittenController < ApplicationController
def index
#variable = 'Hello World'
end
end
In your view (app/views/kitten/index.html.erb):
<%= #variable %>
Rails controllers setup responses with a render call.
When the call is not performed it instantiates the appropriate view and renders that view. In your case that is index.html.erb
Try this:
render :text => kittens.read[559, 441], :status => kittens.status
Related
this is my first post.
I'm brand new to Rails and I'm attempting to learn how to use it. To be clear, I have a brushing familiarity with Ruby. I'm pretty sure I get the MVC structure, but I'm having trouble understanding certain behaviors I'm experiencing.
Just in case anyone learned from the same source, I'm watching Derek Banas explain it. He explains the thing I'm having trouble with around 16:20. https://www.youtube.com/watch?v=GY7Ps8fqGdc
On to specifics- So I placed this line in my routes.rb file:
match':controller(/:action(/:id))', :via => :get
and I created an instance variable in the controller using this:
def sample
#controller_message = "Hello From The Controller"
end
And in a sample view I created, I call on the "controller_message" variable like this:
<%= "#{#controller_message}" %>
And it works on that one view half the time. Now from what I understand, I should see "Hello From The Controller" anywhere that line of code is placed in a view, right? Maybe I just don't understand how this functions, but I made other view files in the same directory in an attempt to see how controllers pass data to views. They load and everything, but I'm not getting the message from the controller. Sometimes, seemingly inconsistently, the controller message won't even display on the first view where it worked originally, especially if I navigate around the site a little. To get it to display that message again, I have to restart my server.
So am I just misunderstanding how MVC works, or is my software glitching (unlikely, I know), or what? I'm so confused.
I've heard so many great things about this community. Thanks in advance to anyone willing to help me. I'm so stressed out.
The #{} in <%= "#{#controller_message}" %>is string interpolation. The usual convention of displaying an instance variable in a view is simply <%= #controller_message %>
The variable #controller_message, declared in the sample method, makes that variable available to the view associated with that method. By default, rails will look for a corresponding view file that has the same name as the controller method, so in this case it will look for a view called sample.html.erb in the app/views/your_controllers_name folder
Well, to clarify things (because your question is a little vague): rails does a lot of stuffs behind the scene, like relating controller's name with view's name. That is why, in most case, you don't invoke a view to be render in controller's method (Rails does that to you based on file's name). So, would make sense the variables declared in a controller method be displayed only in the view with the same name as the controller method called. If you want to display a variable in a view that is not related with the controller method, you should invoke that view with methods like Render and Redirect, and pass the variables as arguments to those methods.
I.g:
other.controller
def edit
render "/another_view_folder/example.html.erb", #variable_to_be_displayed
end
Another thing:
<%= #controller_message %>
This is enough to display the variable. The way you were doing was Interpolation (use to concatenate variable with strings).
I hope I can help you!
Rails will implicitly render a view file if it is found in the view path.
So given:
# config/routes.rb
get 'foos/bar'
# app/controllers/foo_controller.rb
class FoosController < ApplicationController
def bar
#controller_message = 'Hello'
end
end
Rails will attempt to find the file bar.html.erb in app/views/foos when we request /foos/bar. If we want to render another view we need to tell rails to render it explicitly.
class FoosController < ApplicationController
def bar
#controller_message = 'Hello'
render 'some_other_view' # renders app/views/foos/some_other_view.html.erb
# or
render 'some_other_folder/some_other_view' # renders app/views/some_other_folder/some_other_view.html.erb
end
end
Now from what I understand, I should see "Hello From The Controller" anywhere that line of code is placed in a view, right?
No. Lets say you add another controller and view.
# config/routes.rb
get 'people', to: 'people#index'
# app/controllers/people_controller.rb
class PeopleController < ApplicationController
def index
end
end
# app/views/people/index.html.erb
<h1>The message is: <%= #controller_message %></h1>
It will just render The message is:. Since PeopleController does not set the instance variable #controller_message. Ruby will not raise an error if you reference an unassigned instance variable.
The way to reason about this is that the controller in Rails packages all its instance variables and passes them to the view context so that we can use them in the view.
After the controller has finished rendering it sends the rendered template and the program exits*. Instance variables, local variables etc, do not carry over to the next request.
May be my question it's a little weird for RoR developers, but i'm new in Ruby on Rails, and i only discover this world now - there is some dependencies in views names and definitions in controller?
If i have, for example, view called "parse-public-profile.html.erb" , should i add in controller definition with exactly this name? i mean "def parse-public-profile ... end"
I know, that this is basic, but simply i try to understand how controller knows, what views i have now; what i should change, if i will add/change-name of view, or how to define view, if in my "views" folder, i have another folder, for ex. "clients"
Thanks!
Rails follows REST this means methods as index, show, edit, update, destroy etc. are very common in an Rails controller. When you have a custom action(method) however on your controller Rails will look for the corresponding view file, so for example:
class UsersController < ApplicationController
def another_action
end
end
will try to render: app/views/users/another_action.html.erb
There is also the concept of partials which are normally called within a view file f.e. in users/index.html.erb
<% render :partial => 'form' %>
will try to render: app/views/users/_form.html.erb (note the _)
An in depth explanation can be found in the Rails guides
You can also use:
def index
render :template => "users/parse-public-profile"
end
The :template over rides the default file that Rails would have rendered.
For more info, see the Rails Guide on Layouts and Rendering at http://guides.rubyonrails.org/layouts_and_rendering.html.
OK, this is working but I feel there is a better way to do this in Rails... I have a home page which, if you have not signed in, is not currently pulling in anything from any model or controller. It exists at /pages/home.html.erb
On that page, I want to grab the next party from my Parties model and tell the website visitor about that party. Easy enough, right?:
/app/controllers/parties_controller.rb
def nextparty
#party = Party.find(:first, :order => "begins_on")
end
Now, in my home page, I used this and it works fine:
/app/views/pages/home.html.erb
<% #PartyCont = PartiesController.new() %>
<% #party = #PartyCont.nextparty() %>
<h3>The next party is <%= #party.name %></h3>
I tried helper methods, partials, ApplicationHelper, but this was the only code that actually worked. Most of the other things I tried seemed to fail because the #Party class was not instantiated (typically the error indicated the class with a temporary name and "undefined method").
Hey, I'm happy that it works, but I feel like there is a better way in Rails. I've seen a few posts that use code like the above example and then say "But you really shouldn't ever need to do this!".
Is this just fine, or is there a more Rails-like way?
UPDATE:
I think the problem is more than just elegance... I just realized that all RSPEC tests that hit the home page are failing with:
Failure/Error: get 'home'
ActionView::Template::Error:
undefined method `begins_on' for nil:NilClass
Thanks!
You want a controller behind every view and you don't want views crossing controller boundaries in order to present information. Consider having a welcome controller (or whatever you prefer to call it). It can have an index action:
def index
#party = Party.find(:first, :order => "begins_on")
end
In config/routes.rb, make it the root controller action:
root :to => "welcome#index"
Also, to DRY that up add a .nextparty class method to the Party model and call that from both of your controller actions instead of the find method.
Your view should only show data that already was made available by your controller. You want to display a party resource, so the request should go to the parties controller. If I understand your use case correctly, than more specifically to the index method on the PartiesController.
There you should have the following code:
def index
#party = Party.find(:first, :order => "begins_on")
end
That instance method will be available in your corresponding view app/views/parties/index.html.erb
<h3>The next party is <%= #party.name %></h3>
To make this available as your homepage you will have to adjust your route as well:
config/routes.rb
root :to => "parties#index"
Your view should contain as little logic as possible and mainly be concerned with how things look.
Your controller should get data for the view ready and make sure to call the right method on the model.
All the heavy business logic should be in your model.
I think you should work through a basic introductory Rails tutorial.
In my model I have:
after_create :push_create
I push_create I need to render a view. I'm trying to do that like so:
def push_event(event_type)
X["XXXXX-#{Rails.env}"].trigger(event_type,
{
:content => render( :partial =>"feeds/feed_item", :locals => { :feed_item => self })
}
)
end
This angers rails as it doesn't like me rendering a view in the model but I need it there.
Error:
NoMethodError (undefined method `render' for #<WallFeed:0x1039be070>):
Suggestions? Should I render it somewhere else somehow? Or how can I render in the model to set content? Thanks
proper solution
Well, "they" are right. You really have to do the rendering in a controller -
but it's fair game to call that controller from a model! Fortunately, AbstractController
in Rails 3 makes it easier than I thought. I wound up making a simple
ActionPusher class, working just like ActionMailer. Perhaps I'll get ambitious and
make this a proper gem someday, but this should serve as a good start for anyone else in my shoes.
I got the most help from this link: http://www.amberbit.com/blog/2011/12/27/render-views-and-partials-outside-controllers-in-rails-3/
in lib/action_pusher.rb
class ActionPusher < AbstractController::Base
include AbstractController::Rendering
include AbstractController::Helpers
include AbstractController::Translation
include AbstractController::AssetPaths
include Rails.application.routes.url_helpers
helper ApplicationHelper
self.view_paths = "app/views"
class Pushable
def initialize(channel, pushtext)
#channel = channel
#pushtext = pushtext
end
def push
Pusher[#channel].trigger('rjs_push', #pushtext )
end
end
end
in app/pushers/users_pusher.rb. I guess the require could go somewhere more global?
require 'action_pusher'
class UsersPusher < ActionPusher
def initialize(user)
#user = user
end
def channel
#user.pusher_key
end
def add_notice(notice = nil)
#notice = notice
Pushable.new channel, render(template: 'users_pusher/add_notice')
end
end
Now in my model, I can just do this:
after_commit :push_add_notice
private
def push_add_notice
UsersPusher.new(user).add_notice(self).push
end
and then you'll want a partial, e.g. app/views/users_pusher/add_notice.js.haml, which could be as simple as:
alert('#{#notice.body}')
I guess you don't really need to do it with Pushable inner class and the .push
call at the end, but I wanted to make it look like ActiveMailer. I also have a
pusher_key method on my user model, to make a channel for each user - but this
is my first day with anything like Pusher, so I can't say for sure if that's the right
strategy. There's more to be fleshed out, but this is enough for me to get started.
Good luck!
(this was my first draft answer, leaving it in because it might help someone)
I've got the general outline of a solution working. Like this, in your model:
after_create :push_new_message
private
def render_anywhere(partial, assigns = {})
view = ActionView::Base.new(ActionController::Base.view_paths, assigns)
view.extend ApplicationHelper
view.render(:partial => partial)
end
def push_new_message
pushstring = render_anywhere('notices/push_new_message', :message_text => self.body)
Pusher[user.pusher_key].trigger!('new_message', pushstring)
end
that is definitely working - the template is rendering, and gets eval()'ed on the client side successfully. I'm planning to clean it up, almost certainly move render_anywhere somewhere more general, and probably try something like this
I can see that pushes will need their own templates, calling the generally available ones, and I may try to collect them all in one place. One nice little problem is that I sometimes use controller_name in my partials, like to light up a menu item, but I'll obviously have to take a different tactic there. I'm guessing I might have to do something to get more helpers available, but I haven't gotten there yet.
Success! Hooray! This should answer your question, and mine - I'll add more detail if it seems appropriate later. Good luck!!!!
original non-answer from an hour ago left for clarity
I don't have an answer, but this timely question deserves more clarification, and I'm hoping to get closer to my answer by helping ask :)
I'm facing the same problem. To explain a little more clearly, Pusher asynchronously sends content to a connected user browser. A typical use case would be a showing the user they have a new message from another user. With Pusher, you can push a message to the receiver's browser, so they get an immediate notification if they are logged in. For a really great demo of what Pusher can do, check out http://wordsquared.com/
You can send any data you like, such as a JSON hash to interpret how you like it, but it would be very convenient to send RJS, just like with any other ajax call and eval() it on the client side. That way, you could (for example) render the template for your menu bar, updating it in its entirety, or just the new message count displayed to the user, using all the same partials to keep it bone-DRY. In principle, you could render the partial from the sender's controller, but that doesn't make much sense either, and there might not even be a request, it could be triggered by a cron job, for example, or some other event, like a stock price change. The sender controller just should not have to know about it - I like to keep my controllers on a starvation diet ;)
It might sound like a violation of MVC, but it's really not - and it really should be solved with something like ActionMailer, but sharing helpers and partials with the rest of the app. I know in my app, I'd like to send a Pusher event at the same time as (or instead of) an ActionMailer call. I want to render an arbitrary partial for user B based on an event from user A.
These links may point the way towards a solution:
http://blog.choonkeat.com/weblog/2006/08/rails-calling-r.html
How to render a Partial from a Model in Rails 2.3.5
http://mattwindsurfs.wordpress.com/2008/06/19/rails-render-in-a-model/
http://davetroy.blogspot.com/2008/02/actsasrenderer-brings-output-to-models.html
https://github.com/asapnet/acts_as_renderer
http://ethilien.net/archives/render-rails-templates-anywhere-even-in-a-model/
The last one looks the most promising, offering up this tantalizing snippet:
def render_anywhere(partial, assigns)
view = ActionView::Base.new(Rails::Configuration.new.view_path, assigns)
ActionView::Base.helper_modules.each { |helper| view.extend helper }
view.extend ApplicationHelper
view.render(:partial => partial)
end
As does this link provided by another poster above.
I'll report back if I get something working
tl;dr: me too!
I just do this:
ApplicationController.new.render_to_string(partial: 'messages/any', locals: { variable: 'value' })
Rails 5 way
In Rails 5 rendering outside a controller became pretty straightforward due to implemented render controller class method:
# render template
ApplicationController.render 'templates/name'
# render action
FooController.render :index
# render file
ApplicationController.render file: 'path'
# render inline
ApplicationController.render inline: 'erb content'
When calling render outside of a controller, one can assign instance variables via assigns option and use any other options available from within a controller:
ApplicationController.render(
assigns: { article: Article.take },
template: 'articles/show',
layout: false
)
Request environment can be tailored either through default options
ApplicationController.render inline: '<%= users_url %>'
# => 'http://default_host.com/users'
ApplicationController.renderer.defaults[:http_host] = 'custom_host.org'
# => "custom_host.org"
ApplicationController.render inline: '<%= users_url %>'
# => 'http://custom_host.org/users'
or explicitly by initializing a new renderer
renderer = ApplicationController.renderer.new(
http_host: 'custom_host.org',
https: true
)
renderer.render inline: '<%= users_url %>'
# => 'https://custom_host.org/users'
Hope that helps.
You can use ActionView directly and render partials to string without having a controller. I find that pattern useful to create models that encapsulate some javascript generation, for instance.
html = ActionView::Base.new(Rails.configuration.paths['app/views']).render(
partial: 'test',
formats: [:html],
handlers: [:erb],
locals: { variable: 'value' }
)
Then, just put your _test.html.erb in you view folder and try it out!
Rails 6.0.0 compatible answer, since I ended up on this page while searching for a solution:
lookup_context = ActionView::LookupContext.new(Rails.configuration.paths["app/views"])
renderer = ActionView::Base.new(lookup_context)
renderer.extend(Rails.application.helpers)
renderer.render \
template: "foo/bar",
formats: [:html],
handlers: [:erb],
locals: { user: User.new }
I'm fairly sure the answers you seek lie within Crafting Rails Applications where Jose Valim goes into great detail about how and why you would want to render views straight from your db
Sorry I can't be of more help yet because I've just started reading it myself tonight.
You might find some help here - it's a blog post about doing this sort of thing, albeit using different methods than yours
the "proper" way to do this is to push an object in serialized form(json), and then have the view deal with it once the event is received. Perhaps you want to use Handlebars to render the object.
Edit: I originally wrote about how, despite my answer, I was going to follow your example. But I just realized there is a HUGE gotcha with your approach when it comes to push notifications.
In your problem, you are doing push notifications to one user. For me, I was broadcasting out to a set of users. So I was going to render html with a presumption of a "current_user" and all that comes with it(eg logic, permissions, etc). This is NO BUENO as each push notification will be received by a different "current user".
Therefore, really, you need to just send back the data, and let each individual view handle it.
You should call all render methods from a controller. So, in this case, you can notify the controller that the object has been created and the controller can then render the view. Also, since you can render only once, I think you can wait for all your server side operations to complete before invoking the render.
The render methods are defined on the ActiveController class and its progeny. Inherently you do not have access to it on the model, nor is it a class method so you can't use it without an instance of the controller.
I've never tried to instantiate a controller for the express purpose of simply stringifying a partial, but if you can get your hands on a controller, render_to_string seems to be the way to go.
I will chime in by saying that if you're going down this path you're taking RoR "off the Rails". This is a violation of MVC and fundamentally poor program design.This doesn't mean I think you're a bad person :P Sometimes life drives us off the rails, so to speak.
I can't speak to the details that have driven you to do this, but I'd strongly suggest you rethink your approach.
I have created a gist for this.
I needed something similar, where the models don't necessarily (or in my case, ever) get updated via a controller, so the logic can't sit there.
Created a server-push based controller:
https://gist.github.com/4707055
I am building my first app with ROR and stumbled upon a couple of problems due to my understanding of the MVC
I have a page to add a new item, and this works fine, rails magically hooks it up to the items controller and somehow by magic it knows to look in the method 'new' as the page is called new.
But this layer is confusing me, as i need to now create a different version of new, same functionality but with a different look so to use a different layout to application.html.erb
So i attempt to create a copy of new.html.erb and create bookmarklet.html.erb - both contain exactly the same code: a link to a form. but of course bookmarklet will error on me because it does not have that link in the controller - how do i 'wire' up bookmarklet so that i can call the new method and so that it can behave in a similar way to the identical new.html.erb
Also, how can i tell the new bookmarklet.html.erb to ignore the application.html.erb and get its layout from another file?
thanks in advance
The magic happens in the routes. Rails uses something called RESTful routes, which is taking HTTP verbs and assigning standard actions to it. the new action is a GET request in HTTP speak, and if you are using scaffolding or following REST, will have the ruby call to build a new object in the controller, as an instance variable so you can use it in your view.
You have to tell rails routes that you want to BREAK this arrangement and to let /items/bookmarklet be used in the controller.
In your routes.rb file replace resources :items with
resources items do
member do
get 'bookmarklet'
end
end
In your controller put:
def bookmarklet
#item = Item.new
render :template => "bookmarklet", :layout => "different_layout" # or you can put this on the top of the controller, which is my style, but whatevs.
end
You should look into partials, if you are doing this as they clean up your code immensely.
A better way to think of things is to start with the controller instead of the view html.erb files. So each public method in your controller is effectively a page or action in the site. When you need a new action or page, add the method to the controller first. Then create the relevant view files.
So in your controller you'll need something like:
def bookmarklet
#item = Item.new(params[:item])
#item.save
render :template => "items/bookmarklet.html.erb", :layout => "different_layout.html.erb"
end
Normally you don't need to call render manually in the controller, but since you want a different layout than the default you need to specify it using render.