Rails%203%20In%20Action

146 CHAPTER 7 Basic access control
You’ll define the admins_only method soon, and it’ll take a block. Inside this block,
you specify all the content you want shown if the user is an admin. No content will be
shown if the user is not an admin. To define the admins_only helper, open app/helpers
/application_helper.rb and define the method inside the module using this code:
def admins_only(&block)
block.call if current_user.try(:admin?)
nil
end
The admins_only method takes a block, which is the code between the do and end in
your view. To run this code inside the method, call block.call, which runs the specified
block but only if current_user.try(:admin?) returns a value that evaluates to
true. This try method tries a method on an object, and if that method doesn’t exist
(as it wouldn’t if current_user were nil), then it returns nil. At the end of the
method, you return nil so the content doesn’t show again.
When you run this feature using bin/cucumber features/hidden_links.feature,
it passes:
3 scenarios (3 passed)
12 steps (12 passed)
Now that you’ve got the New Project link hiding if the user isn’t an admin, let’s do the
same thing for the Edit Project and Delete Project links.
7.3.3 Hiding the edit and delete links
Add this admins_only helper to the Edit Project and Delete Project links on the projects
show view, but not before adding further scenarios to cover these links to features/
hidden_links.feature, as shown in the following listing.
Listing 7.14 features/hidden_links.feature
Scenario: Edit project link is hidden for non-signed-in users
Given I am on the homepage
When I follow "TextMate 2"
Then I should not see the "Edit Project" link
Scenario: Edit project link is hidden for signed-in users
Given I am signed in as "user@ticketee.com"
When I follow "TextMate 2"
Then I should not see the "Edit Project" link
Scenario: Edit project link is shown to admins
Given I am signed in as "admin@ticketee.com"
When I follow "TextMate 2"
Then I should see the "Edit Project" link