Home > Articles > Programming > Ruby

This chapter is from the book

This chapter is from the book

3.11 The RESTful Rails Action Set

Rails REST facilities, ultimately, are about named routes and the controller actions to which they point. The more you use RESTful Rails, the more you get to know each of the seven RESTful actions. How they work across different controllers (and different applications) is of course somewhat different. Still, perhaps because there's a finite number of them and their roles are fairly well-delineated, each of the seven tends to have fairly consistent properties and a characteristic feel to it.

We're going to take a look at each of the seven actions, with examples and comments. You'll encounter all of them again, particularly in Chapter 4, Working with Controllers, but here you'll get some backstory and start to get a sense of the characteristic usage of them and issues and choices associated with them.

3.11.1 Index

Typically, an index action provides a representation of a plural (or collection) resource. However, to be clear, not all resource collections are mapped to the index action. Your default index representations will usually be generic, although admittedly that has a lot to do with your application-specific needs. But in general, the index action shows the world the most neutral representation possible. A very basic index action looks like

class AuctionsController < ApplicationController
  def index
    @auctions = Auction.all
  end
end

The associated view template will display information about each auction, with links to specific information about each one, and to profiles of the sellers.

You'll certainly encounter situations where you want to display a representation of a collection in a restricted way. In our recurring example, users should be able to see a listing of all their bids, but may be you don't want users seeing other people's bids.

There are a couple of ways to do this. One way is to test for the presence of a logged-in user and decide what to show based on that. But that's not going to work here. For one thing, the logged-in user might want to see the more public view. For another, the more dependence on server-side state we can eliminate or consolidate, the better.

So let's try looking at the two bid lists, not as public and private versions of the same resource, but as different index resources. The difference can be reflected in the routing like:

resources :auctions do
  resources :bids do
    get :manage, :on => :collection
  end
end
resources :bids

We can now organize the bids controller in such a way that access is nicely layered, using filters only where necessary and eliminating conditional branching in the actions themselves:

class BidsController < ApplicationController
  before_filter :check_authorization, :only => :manage

  def index
    @bids = Bid.all
  end

  def manage
    @bids = auction.bids
  end

  protected

    def auction
      @auction ||= Auction.find(params[:auction_id])
    end

    def check_authorization
      auction.authorized?(current_user)
    end

end

There's now a clear distinction between /bids and /auctions/1/bids/manage and the role that they play in your application.

On the named route side, we've now got bids_url and manage_auction_bids_url. We've thus preserved the public, stateless face of the /bids resource, and quarantined as much stateful behavior as possible into a discrete member resource, /auctions/1/bids/manage. Don't fret if this mentality doesn't come to you naturally. It's part of the REST learning curve.

3.11.2 Show

The RESTful show action is the singular flavor of a resource. That generally translates to a representation of information about one object, one member of a collection. Like index, show is triggered by a GET request.

A typical—one might say classic—show action looks like

class AuctionController < ApplicationController
  def show
    @auction = Auction.find(params[:id])
  end
end

You might want to differentiate between publicly available profiles, perhaps based on a different route, and the profile of the current user, which might include modification rights and perhaps different information.

As with index actions, it's good to make your show actions as public as possible and offload the administrative and privileged views onto either a different controller or a different action.

3.11.3 Destroy

Destroy actions are good candidates for administrative safeguarding, though of course it depends on what you're destroying. You might want something like this to protect the destroy action.

class ProductsController < ApplicationController
  before_filter :admin_required, :only => :destroy

A typical destroy action might look like

def destroy
  product.destroy
  flash[:notice] = "Product deleted!"
  redirect_to products_url
end

This approach might be reflected in a simple administrative interface like

%h1 Products
- products.each do |p|
  %p= link_to p.name, product_path(p)
  - if current_user.admin?
    %p= link_to "delete", product_path(p), :method => :delete

That delete link appears depending on whether current user is an admin.

With Rails 3, the UJS (Unobtrusive JavaScript) API greatly simplifies the HTML emitted for a destroy action, using CSS selectors to bind JavaScript to (in this case) the "delete" link. See Chapter 12, Ajax on Rails, for much more information about how it works.

DELETE submissions are dangerous. Rails wants to make them as hard as possible to trigger accidentally—for instance, by a crawler or bot sending requests to your site. So when you specify the DELETE method, JavaScript that submits a form is bound to your "delete" link, along with a rel="nofollow" attribute on the link. Since bots don't submit forms (and shouldn't follow links marked "nofollow"), this gives a layer of protection to your code.

3.11.4 New and Create

As you've already seen, the new and create actions go together in RESTful Rails. A "new resource" is really just an entity waiting to be created. Accordingly, the new action customarily presents a form, and create creates a new record, based on the form input.

Let's say you want a user to be able to create (that is, start) an auction. You're going to need

  1. A new action, which will display a form
  2. A create action, which will create a new Auction object based on the form input, and proceed to a view (show action) of that auction.

The new action doesn't have to do much. In fact, it has to do nothing. Like any empty action, it can even be left out. Rails will still figure out which view to render. However, your controller will need an auction helper method, like

protected

def auction
  @auction ||= current_user.auctions.build(params[:auction])
end
helper_method :auction

If this technique is alien to you, don't worry. We'll describe it in detail in Section 10.1.5.

A simplistic new.html.haml template might look like Listing 3.2.

Listing 3.2. A New Auction Form

%h1 Create a new auction
= form_for auction do |f|
  = f.label :subject
  = f.text_field :subject
  %br
  = f.label :description
  = f.text_field :description
  %br
  = f.label :reserve
  = f.text_field :reserve
  %br
  = f.label :starting_bid
  = f.text_field :starting_bid
  %br
  = f.label :end_time
  = f.datetime_select :end_time
  %br
  = f.submit "Create"

Once the information is filled out by a user, it's time for the main event: the create action. Unlike new, this action has something to do.

def create
  if auction.save
    redirect_to auction_url(auction), :notice => "Auction created!"
  else
    render :action => "new"
  end
end

3.11.5 Edit and Update

Like new and create, the edit and update actions go together: edit provides a form, and update processes the form input.

The form for editing a record appears similar to the form for creating one. (In fact, you can put much of it in a partial template and use it for both; that's left as an exercise for the reader.)

The form_for method is smart enough to check whether the object you pass to it has been persisted or not. If it has, then it recognizes that you are doing an edit and specifies a PUT method on the form.

InformIT Promotional Mailings & Special Offers

I would like to receive exclusive offers and hear about products from InformIT and its family of brands. I can unsubscribe at any time.

Overview


Pearson Education, Inc., 221 River Street, Hoboken, New Jersey 07030, (Pearson) presents this site to provide information about products and services that can be purchased through this site.

This privacy notice provides an overview of our commitment to privacy and describes how we collect, protect, use and share personal information collected through this site. Please note that other Pearson websites and online products and services have their own separate privacy policies.

Collection and Use of Information


To conduct business and deliver products and services, Pearson collects and uses personal information in several ways in connection with this site, including:

Questions and Inquiries

For inquiries and questions, we collect the inquiry or question, together with name, contact details (email address, phone number and mailing address) and any other additional information voluntarily submitted to us through a Contact Us form or an email. We use this information to address the inquiry and respond to the question.

Online Store

For orders and purchases placed through our online store on this site, we collect order details, name, institution name and address (if applicable), email address, phone number, shipping and billing addresses, credit/debit card information, shipping options and any instructions. We use this information to complete transactions, fulfill orders, communicate with individuals placing orders or visiting the online store, and for related purposes.

Surveys

Pearson may offer opportunities to provide feedback or participate in surveys, including surveys evaluating Pearson products, services or sites. Participation is voluntary. Pearson collects information requested in the survey questions and uses the information to evaluate, support, maintain and improve products, services or sites, develop new products and services, conduct educational research and for other purposes specified in the survey.

Contests and Drawings

Occasionally, we may sponsor a contest or drawing. Participation is optional. Pearson collects name, contact information and other information specified on the entry form for the contest or drawing to conduct the contest or drawing. Pearson may collect additional personal information from the winners of a contest or drawing in order to award the prize and for tax reporting purposes, as required by law.

Newsletters

If you have elected to receive email newsletters or promotional mailings and special offers but want to unsubscribe, simply email information@informit.com.

Service Announcements

On rare occasions it is necessary to send out a strictly service related announcement. For instance, if our service is temporarily suspended for maintenance we might send users an email. Generally, users may not opt-out of these communications, though they can deactivate their account information. However, these communications are not promotional in nature.

Customer Service

We communicate with users on a regular basis to provide requested services and in regard to issues relating to their account we reply via email or phone in accordance with the users' wishes when a user submits their information through our Contact Us form.

Other Collection and Use of Information


Application and System Logs

Pearson automatically collects log data to help ensure the delivery, availability and security of this site. Log data may include technical information about how a user or visitor connected to this site, such as browser type, type of computer/device, operating system, internet service provider and IP address. We use this information for support purposes and to monitor the health of the site, identify problems, improve service, detect unauthorized access and fraudulent activity, prevent and respond to security incidents and appropriately scale computing resources.

Web Analytics

Pearson may use third party web trend analytical services, including Google Analytics, to collect visitor information, such as IP addresses, browser types, referring pages, pages visited and time spent on a particular site. While these analytical services collect and report information on an anonymous basis, they may use cookies to gather web trend information. The information gathered may enable Pearson (but not the third party web trend services) to link information with application and system log data. Pearson uses this information for system administration and to identify problems, improve service, detect unauthorized access and fraudulent activity, prevent and respond to security incidents, appropriately scale computing resources and otherwise support and deliver this site and its services.

Cookies and Related Technologies

This site uses cookies and similar technologies to personalize content, measure traffic patterns, control security, track use and access of information on this site, and provide interest-based messages and advertising. Users can manage and block the use of cookies through their browser. Disabling or blocking certain cookies may limit the functionality of this site.

Do Not Track

This site currently does not respond to Do Not Track signals.

Security


Pearson uses appropriate physical, administrative and technical security measures to protect personal information from unauthorized access, use and disclosure.

Children


This site is not directed to children under the age of 13.

Marketing


Pearson may send or direct marketing communications to users, provided that

  • Pearson will not use personal information collected or processed as a K-12 school service provider for the purpose of directed or targeted advertising.
  • Such marketing is consistent with applicable law and Pearson's legal obligations.
  • Pearson will not knowingly direct or send marketing communications to an individual who has expressed a preference not to receive marketing.
  • Where required by applicable law, express or implied consent to marketing exists and has not been withdrawn.

Pearson may provide personal information to a third party service provider on a restricted basis to provide marketing solely on behalf of Pearson or an affiliate or customer for whom Pearson is a service provider. Marketing preferences may be changed at any time.

Correcting/Updating Personal Information


If a user's personally identifiable information changes (such as your postal address or email address), we provide a way to correct or update that user's personal data provided to us. This can be done on the Account page. If a user no longer desires our service and desires to delete his or her account, please contact us at customer-service@informit.com and we will process the deletion of a user's account.

Choice/Opt-out


Users can always make an informed choice as to whether they should proceed with certain services offered by InformIT. If you choose to remove yourself from our mailing list(s) simply visit the following page and uncheck any communication you no longer want to receive: www.informit.com/u.aspx.

Sale of Personal Information


Pearson does not rent or sell personal information in exchange for any payment of money.

While Pearson does not sell personal information, as defined in Nevada law, Nevada residents may email a request for no sale of their personal information to NevadaDesignatedRequest@pearson.com.

Supplemental Privacy Statement for California Residents


California residents should read our Supplemental privacy statement for California residents in conjunction with this Privacy Notice. The Supplemental privacy statement for California residents explains Pearson's commitment to comply with California law and applies to personal information of California residents collected in connection with this site and the Services.

Sharing and Disclosure


Pearson may disclose personal information, as follows:

  • As required by law.
  • With the consent of the individual (or their parent, if the individual is a minor)
  • In response to a subpoena, court order or legal process, to the extent permitted or required by law
  • To protect the security and safety of individuals, data, assets and systems, consistent with applicable law
  • In connection the sale, joint venture or other transfer of some or all of its company or assets, subject to the provisions of this Privacy Notice
  • To investigate or address actual or suspected fraud or other illegal activities
  • To exercise its legal rights, including enforcement of the Terms of Use for this site or another contract
  • To affiliated Pearson companies and other companies and organizations who perform work for Pearson and are obligated to protect the privacy of personal information consistent with this Privacy Notice
  • To a school, organization, company or government agency, where Pearson collects or processes the personal information in a school setting or on behalf of such organization, company or government agency.

Links


This web site contains links to other sites. Please be aware that we are not responsible for the privacy practices of such other sites. We encourage our users to be aware when they leave our site and to read the privacy statements of each and every web site that collects Personal Information. This privacy statement applies solely to information collected by this web site.

Requests and Contact


Please contact us about this Privacy Notice or if you have any requests or questions relating to the privacy of your personal information.

Changes to this Privacy Notice


We may revise this Privacy Notice through an updated posting. We will identify the effective date of the revision in the posting. Often, updates are made to provide greater clarity or to comply with changes in regulatory requirements. If the updates involve material changes to the collection, protection, use or disclosure of Personal Information, Pearson will provide notice of the change through a conspicuous notice on this site or other appropriate way. Continued use of the site after the effective date of a posted revision evidences acceptance. Please contact us if you have questions or concerns about the Privacy Notice or any objection to any revisions.

Last Update: November 17, 2020