I need a string of html (something like "<html><body>Hello World</body></html>") for faxing purpose.
I wrote it into a seprate erb file: views/orders/_fax.html.erb ,
and try to render the erb in action: html_data = render(:partial => 'fax').
Here is part of the controller that raises the issue:
respond_to do |format|
if #order.save
html_data = render(:partial => 'fax')
response = fax_machine.send_fax(html_data)
......
format.html { redirect_to #order, notice: 'Order was successfully created.' }
format.json { render json: #order, status: :created, location: #order }
else
format.html { render action: "new" }
format.json { render json: #order.errors, status: :unprocessable_entity }
end
end
It gave me an AbstractController::DoubleRenderError as below:
AbstractController::DoubleRenderError in OrdersController#create
Render and/or redirect were called multiple times in this action. Please note that you may only call render OR redirect, and at most once per action. Also note that neither redirect nor render terminate execution of the action, so if you want to exit an action after redirecting, you need to do something like "redirect_to(...) and return".
How to solve this problem?
If you only need the rendered HTML, and don't need any functionality from the controller, you might try using ERB directly within a helper class, eg.:
module FaxHelper
def to_fax
html = File.open(path_to_template).read
template = ERB.new(html)
template.result
end
end
The ERB docs explain this in more detail.
EDIT
To get the instance variables from the controller, pass the binding into the result call, eg:
# controller
to_fax(binding)
# helper class
def to_fax(controller_binding)
html = File.open(path_to_template).read
template = ERB.new(html)
template.result(controller_binding)
end
Note: I've never done this, but it seems workable :)
Use the #render_to_string method
it works the same way as the typical render method but useful when you need to add some templated HTML to a json response
http://apidock.com/rails/ActionController/Base/render_to_string
If you don't want to escape html, just call .html_safe on it:
"<html><body>Hello World</body></html>".html_safe
Re your error, please post your OrdersController - looks like you are calling render or redirect more than once in the create action.
(Btw, just in case you are trying it - you can't render a partial in a controller - you can only render partials in views)
Edit: yeah your problem is you trying to render a partial in the controller action. You could use an after_create callback to set up and send the fax - though again you won't want to use a partial (as they are for views). http://api.rubyonrails.org/classes/ActiveRecord/Callbacks.html
Edit: for your fax problem,you could create a normal Ruby Class, see this excellent bit of advice from Yehuda: https://stackoverflow.com/a/1071510/468009
The reason is you cannot render or redirect inside the same action more than once at a given time.
But in your code, you have both render and redirect. I think in your controller you can use simply only the render, assuming you don't need any json output.
Try this
def create
#order.save
render(:partial => 'fax')
end
I haven't tested this, but I guess you get the idea :), and think about a way to handle errors as well (in case order didn't save).
Related
I want to redirect to another page admin_antenna_reader_rfids_path at the end of the create method. I did:
def create
#antenna_reader_rfid = AntennaReaderRfid.new(antenna_reader_rfid_params)
if #antenna_reader_rfid.save
render json: {status: true}
redirect_to admin_antenna_reader_rfid_path(q#antenna_reader_rfid)
else
render json: {errors: #antenna_reader_rfid.errors.full_messages, status: false}
end
end
I get an error AbstractController :: DoubleRenderError:
Render and/or redirect were called multiple times in this action. Please note that you may only call render OR redirect, and at most once per action. Also note that neither redirect nor render terminate execution of the action, so if you want to exit an action after redirecting, you need to do something like "redirect_to(...) and return".
How can I solve this?
You have to remove the line render json: {status: true} as currently you're trying to make your controller render a json and redirect to an HTML page at the same time. You have to pick one.
To handle multiple request format, you can use respond_to
if #antenna_reader_rfid.save
respond_to do |format|
format.json { render json: { status: true } }
format.html { redirect_to where_you_want_path }
end
else
# same way as above
end
Within the respond_to block, you can render all the request formats as you want, then based on the request header, the controller will choose the corresponding logic to respond to you.
You can't render nor return more than once in a method.
Rails scaffold generated the following:
respond_to do |format|
if #student.save
format.html { redirect_to #student, notice => 'Student was successfully created.' }
format.json { render :show, status: :created, location: #student }
else
format.html { render :new }
format.json { render json: #student.errors, status: :unprocessable_entity }
end
end
After reading this I understand how the respond_to is working (sort of), but I don't get what format is doing. Shouldn't it be either format.html or format.json and not both? What are these two lines actually doing?
format.html { render :new }
format.json { render json: #student.errors, status: :unprocessable_entity }
Is there an implied if in there? Is it something like
if (format == html) {}
if (format == json) {}
Side note: Why does update require the respond_to block while show will handle /students/1.json or /students/1 without any logic at all?
format is a local variable that respond_to yields. When you do format.html {} you are actually registering a callback block for a format.
Rails goes through the registered formats and tries to find a compatible format to the MIME type in the request. If there is no handler it will raise an error.
This could be explained as something like using syntactic sugar on top of a case statement (the Ruby equivalent of a switch statement). But the analogy is not completely accurate since Rails does a bit of work in matching the request type.
Also the code inside your block is not executed when the format.html block is registered (as it would be if it was just a conditional statement) but rather when respond_to finishes or not at all if you are using for example E-Tag caching.
Why does update require the respond_to block while show will handle
/students/1.json or /students/1 without any logic at all?
Rails handles many actions by using a convention over configuration approach and guessing the intent of the action.
def PostsController < ApplicationController
def index
# rails auto-magically fills in the controller with something
# like this
#posts = Post.all
respond_to do |format|
format.html { render :index }
format.json { render json: #posts }
end
end
def show
# convention over configuration is awesome!
#post = Post.find(params[:id])
respond_to do |format|
format.html { render :show }
format.json { render json: #post }
end
end
def new
#post = Post.new
render :new
end
def edit
#post = Post.find(params[:id])
render :edit
end
end
Rails assumes that there is a resource with the same name as the controller and auto-magically fills in the controller action. It also assumes there is a view in app/views/posts/(:action).html.[erb|haml|slim|jbuilder]. This is known as implicit rendering.
The comments show roughly what action rails attempts.
It does not fill in actions which operate on data (create, update, destroy) since the actual implementation can vary greatly and it's hard to make useful guesses.
Well, it depends on the format of the request. If a request demands HTML from the server, format.html block will be executed, and in the same way, if a request demands JSON format, format.json will be executed.
Rails will automatically(read: magically) handle the if (format == html) part for you. All you have to do is fill in the blanks. Same way, you can write a block for XML starting with format.xml.
And for the side note, I think you have said it otherwise. update method doesn't require respond_to block, while show requires. And the reason is very simple: update method is there to update the Model, and then, redirect you to somewhere, while show will always return you something. In your case, /students/1 will return you the first student created in the database, and the response will be HTML, while /students/1.json will return you the same result, but response will be JSON this time.
Well you could very well replace 'format' with 'foo' or 'banana' or whatever you want. It is just the variable name in this case because the variable that is sent to your block by respond_to is passing along the format as requested by the incoming http request's Accept header.
Sometimes you'll see 422 "Unacceptable" errors in your logs because you are receiving a request with an Accept header that does not request a mime type your app knows about.
As it is, your callers should be using a browser or be a JSON consumer sending the proper headers to receive responses from the boilerplate.
If I'm using my rails app to mainly respond to json, is having a "new" or "edit" action that returns an empty object in json still necessary/useful? For example:
def new
#post = Post.new
respond_to do |format|
format.json { render :json => #post }
end
end
I feel like I can just get away from making a server call by completely building the forms in html
In my opinion, yes, you can exclude that action if you don't need special default field values and are assembling your form fields manually.
I've got a form with remote => true.
And right now my controller looks like:
# POST /items
# POST /items.json
def create
#item = #store.items.build(params[:item])
respond_to do |format|
if #item.save
format.html { redirect_to edit_admin_item_path(#item), :flash => {:success => "#{#item.name} was successfully created."} }
format.js { render :js => "window.location.href = ('#{edit_admin_item_path(#item)}');"}
format.json { render json: #item, status: :created, location: #item }
else
format.html { render action: "new" }
format.js { render :partial => 'fail_create.js.erb', :locals => { :ajax_errors => #item.errors.full_messages } }
format.json { render json: #item.errors, status: :unprocessable_entity }
end
end
end
Which works but feels very clumsy. It also doesn't allow me to use a flash notice, which is sad time indeed.
Ideally I feel like I should be able to simply use "format.js { redirect_to...} or check against the request headers and redirect_to. Sheesh!
I'm not sure what the best solution is. Any advice would be super awesome, thanks in advance!
-- PS -- I know this has been asked somewhat before but to no avail: How to redirect after a successful AJAX form submission. There seems to many questions similar floating around, but no real solutions.
I think it might be impossible. The response to a Ajax request is processed by XMLHttpRequest. If a 3xx response is returned, XMLHttpRequest will follow the redirect itself, if the URL is of same origin. No matter how you set the headers, the browser cannot be aware of that. So the only way could be changing window.location with some Javascript.
I use a combination of Rails responders to generate my response messages and some content in my <action>.js file.
The content of — say update.js would look something like this:
// Checks if the article slug has changed.
// If it has the entire page should be reloaded at that new location.
<%= reload_if_slug_changed #article, params[:id] %>
// Displays the flash notices
// See ApplicationHelper#js_flash_response
<%= js_flash_response %>
Where the different methods are defined in some helper (in my case my ApplicationHelper). The content of the different methods are as follows:
def js_flash_response
if flash.now[:notice].present?
js = "$('#notice').html('#{flash.now[:notice]}').change();"
elsif flash.now[:alert].present?
js = "$('#alert').html('#{flash.now[:alert]}').change();"
end
end
def reload_if_slug_changed object, expected_value
"window.location.href = '#{url_for [:edit, object]}';" if object.slug != expected_value
end
The content of the flash messages are generated automatically by Rails responders and displayed with the now scope that deletes the from the flash hash, ensuring that if the user reloads (after the flash has been displayed) they will not reappear.
I don't believe that you should ever make a form pointing to a restful create action a remote one, because you would always expect critical redirect, so in my case I only need to redirect if the url slug has changed.
I hope that this helps. It's not a solution, but simply the way that I handled some of the same problems.
Best regards.
Under your scenario, here's how I would inject javascript into the page from a controller action. After you've completed the logic section of your action insert something like this:
render :update do |page|
page << "javascript_here"
end
This should allow you to insert you window.location or create a javascript flash method and call it when your create method executes correctly.
If you're looking to DRY up your controller actions, I would recommend looking into this Railscast about make_resourceful. Make_resourceful automagically performs each core activity for each action. It also allows you to tap into the hooks that they've created such as before :create, after :create, response_for :create, and after :create_fails. By using this gem, you can run code based on the success or failure of your methods and have finer grained control over them.
In addition to this, you should be able to initialize a create.js.erb and create_fails.js.erb in your view file, include a format.js without anything passed to it in your controller, and Rails will automagically run that file that contains javascript depending on if the controller action executed successfully.
Suppose you have an edit form with :remote => true. Your controller method looks like
def update
#article = Article.find(params[:id])
respond_to do |format|
if #article.update_attributes(params[:article])
format.html { redirect_to #article}
format.js { render :js => "window.location.replace('#{article_path(#article)}');"}
else
format.html { render :action => "edit" }
# Render update.js.erb which replaces the body of the form
format.js {}
end
end
end
What's the best way to do the redirect on successful article update in Rails 3.2.1? The raw JS solution seems a little sleazy, but I do like the fact that it's obvious that it's performing the same function as the format.html version.
I would prefer a solution that does not use RJS (if that even works in Rails 3.2?)
How about adding the below line of code on the view file itself
#some_file.js.erb
`window.location = redirect_path
As you mentioned in the question you do not prefer RJS, but I think it's better to follow this pattern better than writing the js code in the controller.
Does your ajax interact with a model (.php,.asp?). My preferred method in this instance is to create a success/fail criteria within the model after submission and redirect directly from there. Not sure if that makes sense in this application though?