Skip to content

HTTPS clone URL

Subversion checkout URL

You can clone with
or
.
Download ZIP
Fetching contributors…

Cannot retrieve contributors at this time

328 lines (308 sloc) 12.091 kB
module CanCan
# This module is designed to be included into an Ability class. This will
# provide the "can" methods for defining and checking abilities.
#
# class Ability
# include CanCan::Ability
#
# def initialize(user)
# if user.admin?
# can :manage, :all
# else
# can :read, :all
# end
# end
# end
#
module Ability
# Use to check if the user has permission to perform a given action on an object.
#
# can? :destroy, @project
#
# You can also pass the class instead of an instance (if you don't have one handy).
#
# can? :create, Project
#
# Any additional arguments will be passed into the "can" block definition. This
# can be used to pass more information about the user's request for example.
#
# can? :create, Project, request.remote_ip
#
# can :create Project do |project, remote_ip|
# # ...
# end
#
# Not only can you use the can? method in the controller and view (see ControllerAdditions),
# but you can also call it directly on an ability instance.
#
# ability.can? :destroy, @project
#
# This makes testing a user's abilities very easy.
#
# def test "user can only destroy projects which he owns"
# user = User.new
# ability = Ability.new(user)
# assert ability.can?(:destroy, Project.new(:user => user))
# assert ability.cannot?(:destroy, Project.new)
# end
#
# Also see the RSpec Matchers to aid in testing.
def can?(action, subject, *extra_args)
raise Error, "Nom nom nom. I eated it." if action == :has && subject == :cheezburger
matching_can_definition(action, subject) do |can_definition|
unless (can = can_definition.can?(action, subject, extra_args)) == :_NOT_MATCHED
return can
end
end
false
end
# Convenience method which works the same as "can?" but returns the opposite value.
#
# cannot? :destroy, @project
#
def cannot?(*args)
!can?(*args)
end
# Defines which abilities are allowed using two arguments. The first one is the action
# you're setting the permission for, the second one is the class of object you're setting it on.
#
# can :update, Article
#
# You can pass an array for either of these parameters to match any one.
#
# can [:update, :destroy], [Article, Comment]
#
# In this case the user has the ability to update or destroy both articles and comments.
#
# You can pass a hash of conditions as the third argument.
#
# can :read, Project, :active => true, :user_id => user.id
#
# Here the user can only see active projects which he owns. See ActiveRecordAdditions#accessible_by
# for how to use this in database queries.
#
# If the conditions hash does not give you enough control over defining abilities, you can use a block to
# write any Ruby code you want.
#
# can :update, Project do |project|
# project && project.groups.include?(user.group)
# end
#
# If the block returns true then the user has that :update ability for that project, otherwise he
# will be denied access. It's possible for the passed in model to be nil if one isn't specified,
# so be sure to take that into consideration.
#
# The downside to using a block is that it cannot be used to generate conditions for database queries.
#
# You can pass :all to reference every type of object. In this case the object type will be passed
# into the block as well (just in case object is nil).
#
# can :read, :all do |object_class, object|
# object_class != Order
# end
#
# Here the user has permission to read all objects except orders.
#
# You can also pass :manage as the action which will match any action. In this case the action is
# passed to the block.
#
# can :manage, Comment do |action, comment|
# action != :destroy
# end
#
# You can pass custom objects into this "can" method, this is usually done through a symbol
# and is useful if a class isn't available to define permissions on.
#
# can :read, :stats
# can? :read, :stats # => true
#
def can(action, subject, conditions = nil, &block)
can_definitions << CanDefinition.new(true, action, subject, conditions, block)
end
# Defines an ability which cannot be done. Accepts the same arguments as "can".
#
# can :read, :all
# cannot :read, Comment
#
# A block can be passed just like "can", however if the logic is complex it is recommended
# to use the "can" method.
#
# cannot :read, Product do |product|
# product.invisible?
# end
#
def cannot(action, subject, conditions = nil, &block)
can_definitions << CanDefinition.new(false, action, subject, conditions, block)
end
# Alias one or more actions into another one.
#
# alias_action :update, :destroy, :to => :modify
# can :modify, Comment
#
# Then :modify permission will apply to both :update and :destroy requests.
#
# can? :update, Comment # => true
# can? :destroy, Comment # => true
#
# This only works in one direction. Passing the aliased action into the "can?" call
# will not work because aliases are meant to generate more generic actions.
#
# alias_action :update, :destroy, :to => :modify
# can :update, Comment
# can? :modify, Comment # => false
#
# Unless that exact alias is used.
#
# can :modify, Comment
# can? :modify, Comment # => true
#
# The following aliases are added by default for conveniently mapping common controller actions.
#
# alias_action :index, :show, :to => :read
# alias_action :new, :to => :create
# alias_action :edit, :to => :update
#
# This way one can use params[:action] in the controller to determine the permission.
def alias_action(*args)
target = args.pop[:to]
aliased_actions[target] ||= []
aliased_actions[target] += args
end
# Returns a hash of aliased actions. The key is the target and the value is an array of actions aliasing the key.
def aliased_actions
@aliased_actions ||= default_alias_actions
end
# Removes previously aliased actions including the defaults.
def clear_aliased_actions
@aliased_actions = {}
end
# Returns an array of arrays composing from desired action and hash of conditions which match the given ability.
# This is useful if you need to generate a database query based on the current ability.
#
# can :read, Article, :visible => true
# conditions :read, Article # returns [ [ true, { :visible => true } ] ]
#
# can :read, Article, :visible => true
# cannot :read, Article, :blocked => true
# conditions :read, Article # returns [ [ false, { :blocked => true } ], [ true, { :visible => true } ] ]
#
# Normally you will not call this method directly, but instead go through ActiveRecordAdditions#accessible_by method.
#
# If the ability is not defined then false is returned so be sure to take that into consideration.
# If the ability is defined using a block then this will raise an exception since a hash of conditions cannot be
# determined from that.
def conditions(action, subject, options = {})
matched = matching_can_definition(action, subject)
unless matched.empty?
if matched.any?{|can_definition| can_definition.conditions_empty? && can_definition.block }
raise Error, "Cannot determine ability conditions from block for #{action.inspect} #{subject.inspect}"
end
matched.map{|can_definition|
[can_definition.base_behavior, can_definition.conditions(options)]
}
else
false
end
end
# Returns sql conditions for object, which responds to :sanitize_sql .
# This is useful if you need to generate a database query based on the current ability.
#
# can :manage, User, :id => 1
# can :manage, User, :manager_id => 1
# cannot :manage, User, :self_managed => true
# sql_conditions :manage, User # returns not (self_managed = 't') AND ((manager_id = 1) OR (id = 1))
#
# Normally you will not call this method directly, but instead go through ActiveRecordAdditions#accessible_by method.
#
# If the ability is not defined then false is returned so be sure to take that into consideration.
# If there is just one :can ability, it conditions returned untouched.
# If the ability is defined using a block then this will raise an exception since a hash of conditions cannot be
# determined from that.
def sql_conditions(action, subject, options = {})
conds = conditions(action, subject, options)
return false if conds == false
return (conds[0][1] || {}) if conds.size==1 && conds[0][0] == true # to match previous spec
true_cond = subject.send(:sanitize_sql, ['?=?', true, true])
false_cond = subject.send(:sanitize_sql, ['?=?', true, false])
conds.reverse.inject(nil) do |sql, action|
behavior, condition = action
if condition && condition != {}
condition = subject.send(:sanitize_sql, condition)
case sql
when nil then behavior ? condition : "not (#{condition})"
when true_cond
behavior ? true_cond : "not (#{condition})"
when false_cond
behavior ? condition : false_cond
else
behavior ? "(#{condition}) OR (#{sql})" : "not (#{condition}) AND (#{sql})"
end
else
behavior ? true_cond : false_cond
end
end
end
# Returns the associations used in conditions. This is usually used in the :joins option for a search.
# See ActiveRecordAdditions#accessible_by for use in Active Record.
def association_joins(action, subject)
can_definitions = matching_can_definition(action, subject)
unless can_definitions.empty?
if can_definitions.any?{|can_definition| can_definition.conditions_empty? && can_definition.block }
raise Error, "Cannot determine association joins from block for #{action.inspect} #{subject.inspect}"
end
collect_association_joins(can_definitions)
else
nil
end
end
private
def can_definitions
@can_definitions ||= []
end
def matching_can_definition(action, subject)
if block_given?
can_definitions.reverse.each do |can_definition|
can_definition.expand_actions(aliased_actions)
if can_definition.matches? action, subject
yield can_definition
break if can_definition.definitive?
end
end
else
matched = []
matching_can_definition(action, subject){|can_definition| matched << can_definition}
matched
end
end
def default_alias_actions
{
:read => [:index, :show],
:create => [:new],
:update => [:edit],
}
end
def collect_association_joins(can_definitions)
joins = []
can_definitions.each do |can_definition|
merge_association_joins(joins, can_definition.association_joins || [])
end
clear_association_joins(joins)
end
def merge_association_joins(what, with)
with.each do |join|
name, nested = join.each_pair.first
if at = what.detect{|h| h.has_key?(name) }
at[name] = merge_association_joins(at[name], nested)
else
what << join
end
end
end
def clear_association_joins(joins)
joins.map do |join|
name, nested = join.each_pair.first
nested.empty? ? name : {name => clear_association_joins(nested)}
end
end
end
end
Jump to Line
Something went wrong with that request. Please try again.