300 lines
11 KiB
Ruby
300 lines
11 KiB
Ruby
module CanCan
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# This module is designed to be included into an Ability class. This will
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# provide the "can" methods for defining and checking abilities.
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#
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# class Ability
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# include CanCan::Ability
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#
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# def initialize(user)
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# if user.admin?
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# can :manage, :all
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# else
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# can :read, :all
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# end
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# end
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# end
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#
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module Ability
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# Check if the user has permission to perform a given action on an object.
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#
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# can? :destroy, @project
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#
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# You can also pass the class instead of an instance (if you don't have one handy).
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#
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# can? :create, Project
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#
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# Nested resources can be passed through a hash, this way conditions which are
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# dependent upon the association will work when using a class.
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#
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# can? :create, @category => Project
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#
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# Any additional arguments will be passed into the "can" block definition. This
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# can be used to pass more information about the user's request for example.
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#
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# can? :create, Project, request.remote_ip
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#
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# can :create Project do |project, remote_ip|
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# # ...
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# end
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#
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# Not only can you use the can? method in the controller and view (see ControllerAdditions),
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# but you can also call it directly on an ability instance.
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#
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# ability.can? :destroy, @project
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#
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# This makes testing a user's abilities very easy.
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#
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# def test "user can only destroy projects which he owns"
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# user = User.new
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# ability = Ability.new(user)
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# assert ability.can?(:destroy, Project.new(:user => user))
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# assert ability.cannot?(:destroy, Project.new)
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# end
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#
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# Also see the RSpec Matchers to aid in testing.
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def can?(action, subject, *extra_args)
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match = relevant_can_definitions_for_match(action, subject).detect do |can_definition|
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can_definition.matches_conditions?(action, subject, extra_args)
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end
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match ? match.base_behavior : false
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end
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# Convenience method which works the same as "can?" but returns the opposite value.
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#
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# cannot? :destroy, @project
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#
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def cannot?(*args)
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!can?(*args)
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end
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# Defines which abilities are allowed using two arguments. The first one is the action
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# you're setting the permission for, the second one is the class of object you're setting it on.
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#
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# can :update, Article
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#
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# You can pass an array for either of these parameters to match any one.
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# Here the user has the ability to update or destroy both articles and comments.
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#
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# can [:update, :destroy], [Article, Comment]
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#
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# You can pass :all to match any object and :manage to match any action. Here are some examples.
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#
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# can :manage, :all
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# can :update, :all
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# can :manage, Project
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#
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# You can pass a hash of conditions as the third argument. Here the user can only see active projects which he owns.
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#
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# can :read, Project, :active => true, :user_id => user.id
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#
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# See ActiveRecordAdditions#accessible_by for how to use this in database queries. These conditions
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# are also used for initial attributes when building a record in ControllerAdditions#load_resource.
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#
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# If the conditions hash does not give you enough control over defining abilities, you can use a block
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# along with any Ruby code you want.
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#
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# can :update, Project do |project|
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# project.groups.include?(user.group)
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# end
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#
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# If the block returns true then the user has that :update ability for that project, otherwise he
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# will be denied access. The downside to using a block is that it cannot be used to generate
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# conditions for database queries.
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#
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# You can pass custom objects into this "can" method, this is usually done with a symbol
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# and is useful if a class isn't available to define permissions on.
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#
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# can :read, :stats
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# can? :read, :stats # => true
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#
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# IMPORTANT: Neither a hash of conditions or a block will be used when checking permission on a class.
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#
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# can :update, Project, :priority => 3
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# can? :update, Project # => true
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#
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# If you pass no arguments to +can+, the action, class, and object will be passed to the block and the
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# block will always be executed. This allows you to override the full behavior if the permissions are
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# defined in an external source such as the database.
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#
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# can do |action, object_class, object|
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# # check the database and return true/false
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# end
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#
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def can(action = nil, subject = nil, conditions = nil, &block)
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can_definitions << CanDefinition.new(true, action, subject, conditions, block)
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end
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# Defines an ability which cannot be done. Accepts the same arguments as "can".
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#
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# can :read, :all
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# cannot :read, Comment
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#
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# A block can be passed just like "can", however if the logic is complex it is recommended
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# to use the "can" method.
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#
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# cannot :read, Product do |product|
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# product.invisible?
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# end
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#
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def cannot(action = nil, subject = nil, conditions = nil, &block)
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can_definitions << CanDefinition.new(false, action, subject, conditions, block)
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end
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# Alias one or more actions into another one.
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#
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# alias_action :update, :destroy, :to => :modify
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# can :modify, Comment
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#
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# Then :modify permission will apply to both :update and :destroy requests.
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#
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# can? :update, Comment # => true
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# can? :destroy, Comment # => true
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#
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# This only works in one direction. Passing the aliased action into the "can?" call
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# will not work because aliases are meant to generate more generic actions.
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#
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# alias_action :update, :destroy, :to => :modify
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# can :update, Comment
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# can? :modify, Comment # => false
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#
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# Unless that exact alias is used.
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#
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# can :modify, Comment
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# can? :modify, Comment # => true
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#
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# The following aliases are added by default for conveniently mapping common controller actions.
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#
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# alias_action :index, :show, :to => :read
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# alias_action :new, :to => :create
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# alias_action :edit, :to => :update
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#
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# This way one can use params[:action] in the controller to determine the permission.
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def alias_action(*args)
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target = args.pop[:to]
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aliased_actions[target] ||= []
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aliased_actions[target] += args
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end
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# Returns a hash of aliased actions. The key is the target and the value is an array of actions aliasing the key.
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def aliased_actions
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@aliased_actions ||= default_alias_actions
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end
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# Removes previously aliased actions including the defaults.
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def clear_aliased_actions
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@aliased_actions = {}
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end
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# Returns a CanCan::Query instance to help generate database queries based on the ability.
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# If any relevant can definitions use a block then an exception will be raised because an
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# SQL query cannot be generated from blocks of code.
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def query(action, subject)
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Query.new(subject, relevant_can_definitions_for_query(action, subject))
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end
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# See ControllerAdditions#authorize! for documentation.
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def authorize!(action, subject, *args)
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message = nil
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if args.last.kind_of?(Hash) && args.last.has_key?(:message)
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message = args.pop[:message]
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end
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if cannot?(action, subject, *args)
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message ||= unauthorized_message(action, subject)
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raise AccessDenied.new(message, action, subject)
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end
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end
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def unauthorized_message(action, subject)
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keys = unauthorized_message_keys(action, subject)
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variables = {:action => action.to_s}
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variables[:subject] = (subject.class == Class ? subject : subject.class).to_s.downcase
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message = I18n.translate(nil, variables.merge(:scope => :unauthorized, :default => keys + [""]))
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message.blank? ? nil : message
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end
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def attributes_for(action, subject)
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attributes = {}
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relevant_can_definitions(action, subject).map do |can_definition|
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attributes.merge!(can_definition.attributes_from_conditions) if can_definition.base_behavior
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end
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attributes
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end
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def has_block?(action, subject)
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relevant_can_definitions(action, subject).any?(&:only_block?)
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end
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def has_raw_sql?(action, subject)
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relevant_can_definitions(action, subject).any?(&:only_raw_sql?)
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end
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private
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def unauthorized_message_keys(action, subject)
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subject = (subject.class == Class ? subject : subject.class).name.underscore unless subject.kind_of? Symbol
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[subject, :all].map do |try_subject|
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[aliases_for_action(action), :manage].flatten.map do |try_action|
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:"#{try_action}.#{try_subject}"
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end
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end.flatten
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end
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# Accepts an array of actions and returns an array of actions which match.
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# This should be called before "matches?" and other checking methods since they
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# rely on the actions to be expanded.
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def expand_actions(actions)
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actions.map do |action|
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aliased_actions[action] ? [action, *expand_actions(aliased_actions[action])] : action
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end.flatten
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end
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# Given an action, it will try to find all of the actions which are aliased to it.
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# This does the opposite kind of lookup as expand_actions.
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def aliases_for_action(action)
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results = [action]
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aliased_actions.each do |aliased_action, actions|
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results += aliases_for_action(aliased_action) if actions.include? action
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end
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results
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end
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def can_definitions
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@can_definitions ||= []
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end
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# Returns an array of CanDefinition instances which match the action and subject
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# This does not take into consideration any hash conditions or block statements
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def relevant_can_definitions(action, subject)
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can_definitions.reverse.select do |can_definition|
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can_definition.expanded_actions = expand_actions(can_definition.actions)
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can_definition.relevant? action, subject
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end
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end
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def relevant_can_definitions_for_match(action, subject)
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relevant_can_definitions(action, subject).each do |can_definition|
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if can_definition.only_raw_sql?
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raise Error, "The can? and cannot? call cannot be used with a raw sql 'can' definition. The checking code cannot be determined for #{action.inspect} #{subject.inspect}"
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end
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end
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end
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def relevant_can_definitions_for_query(action, subject)
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relevant_can_definitions(action, subject).each do |can_definition|
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if can_definition.only_block?
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raise Error, "The accessible_by call cannot be used with a block 'can' definition. The SQL cannot be determined for #{action.inspect} #{subject.inspect}"
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end
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end
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end
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def default_alias_actions
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{
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:read => [:index, :show],
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:create => [:new],
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:update => [:edit],
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}
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end
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end
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end
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