I'm a newcomer to Rails, and have been following the tutorial on the rails webpage.
Using the scaffold instruction to create a "post" model, I found that the new action in the controller has a special directive for XML format:
def new
#post = Post.new
respond_to do |format|
format.html # new.html.erb
format.xml { render :xml => #post }
end
end
I can't see the reasoning for supporting an XML request when creating a new post. Browsing to /posts/new.xml returns nothing. What is the purpose of this?
The reasoning for it behind the new action is simply to provide a xml client with the default data (or something else if you want).
The format directive is being used by all routes, and you don't need to support a format unless you want to.
The above code could might as well have looked like:
respond_to do |format|
format.html # renders new.html.erb
format.xml { render :xml => {:message => "XML is not supported"} }
format.json { render :text => #post.to_json }
format.js # renders new.js.erb
end
Also, this is not limited to the new action, but is available in all your actions. The format to use is either taken from the url (if the route is set up to use it), or from the HTTP-Accept header that the browser sends.
Related
I have a Rails controller which provides both HTML and PDF responses, and thus I have view.pdf.haml and view.html.haml files. These are either identical or extremely close to identical.
How can I have Rails use a single view for multiple formats?
You can specify what format to render with :formats option:
# Both will render view.html.haml
respond_to do |format|
format.html { render :view }
format.pdf { render :view, formats: :html }
end
https://guides.rubyonrails.org/layouts_and_rendering.html#the-formats-option
Do you mean have the same action serve up different resource types - i.e. both a web page and a PDF? If I understand the problem, you can use the respond_to method.
def show
#object = Object.find params[:id]
respond_to do |format|
format.html
format.pdf { ..code to render the pdf.. }
end
end
That ..code to render the pdf.. is the tricky part. There are PDF gems that support inline rendering, but you may end up using send_data or similar to set a file name, disposition, etc and deliver the PDF document to the end user.
I'm running Rails 2.3.8 and I have a respond_to in my Projects controller create action.
def create
respond_to do |format|
format.html { redirect_to('/') }
format.json :status => 200
end
end
I have an AJAX call to this action. The Rails application then renders
projectdocs/create.erb
My question is, how can I change this file path within my action from create.erb to create.erb.js.
I think your controller-name would be "projectdocs" an not "Project" if he renders "projectdocs/create.erb", but that's not the point.
You can explicit render a js-file using
format.js { render :action => 'create' }
if this Format is requested.
It depends on called format. If client wants js, add format.js and rails will try to render first of all create.js.erb
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 have seen some people using code like this
respond_to do |format|
format.html
format.js
end
What is the purpose of this if we have template.html and template.js. Either can be rendered without specifying respond_to
Your snippet doesn't do anything special, but the formatting options allow you to provide additional custom behavior if it is necessary.
For example, if you want to render your #products as a JSON:
respond_to do |format|
format.html
format.js { render :json => #products }
end
This is just one of the many things you can do with the format blocks. For more information, see Ruby on Rails Guides: Layouts and Rendering
The format options can take a block so that you can do some custom rendering such as rendering a file or :head response. Have a look at some of the examples here
If you don't specify different behavior for the different formats there is no reason to use respond_to. If you have templates they will automatically be picked up by rails. The respond_to method is useful if you need different behavior per format:
respond_to do |format|
format.html { render :edit }
format.json { render :json => '{}' }
end
I am an experienced JAVA and C++ developer and I am trying to understand how rails works.
I got this code below:
respond_to do |format|
if #line_item.save
format.html { redirect_to store_url }
format.js { render :json => #line_item, :mime_type => Mime::Type.lookup('application/json'),
:callback => 'javascriptFunction' }
and I've been searching the api that defines what I can pass inside the format.js {} but I could not find..
first of all: what kind of statement is format.js, is that a variable?
and most important: what attributes can I pass into format.js {} ? can you pass the direct link? I've searched over the http://api.rubyonrails.org/
respond_to do |format|
format.js # actually means: if the client ask for js -> return file.js
end
js here specifies a mime-type that the controller method would send back as a response;
Default Rails mime-types.
If you try also with format.yaml:
respond_to do |format|
format.js
format.yaml
end
that will mean that your controller will return yml or js depending on what the client-side is asking;
{} in terms of ruby is a block;
If you don't specify any rails will try to render a default file from app/views/[contoller name]/[controller method name].[html/js/...]
# app/controllers/some_controller.rb
def hello
respond_to do |format|
format.js
end
end
will look for /app/views/some/hello.js.erb; // at least in Rails v. 2.3.
If you do specify block:
respond_to do |format|
# that will mean to send a javascript code to client-side;
format.js { render
# raw javascript to be executed on client-side
"alert('Hello Rails');",
# send HTTP response code on header
:status => 404, # page not found
# load /app/views/your-controller/different_action.js.erb
:action => "different_action",
# send json file with #line_item variable as json
:json => #line_item,
:file => filename,
:text => "OK",
# the :location option to set the HTTP Location header
:location => path_to_controller_method_url(argument)
}
end
I believe this was the url you were looking for:
https://apidock.com/rails/ActionController/MimeResponds/InstanceMethods/respond_to
This might also be helpful to some, to see that you can actually render js directly within the format.js method, if you for example only have a small one line js statement you want to return, and you don't want to defer to a RJS file like controller_action_name.js.erb:
respond_to do |format|
format.html { redirect_to new_admin_session_path }
format.js { render :js => "window.location='#{ new_admin_session_path }'" }
end