获取代表用户的CanCan功能的字符串 [英] Get a string that represents a user's CanCan abilities

问题描述

我想缓存Post视图，但是该视图取决于当前用户的权限(例如，如果current_user.can?(:edit, @post)，我仅显示"edit"链接)

I want to cache a Post view, but the view depends on the permissions of the current user (e.g., I only show the "edit" link if current_user.can?(:edit, @post))

因此，我希望我的缓存键包括当前用户的CanCan能力的表示形式，以便我可以在用户能力发生变化时使缓存无效

So I'd like my cache key to include a representation of the current user's CanCan abilities, so that I can invalidate the cache when the user's abilities change

SO:我如何获得一个表示当前用户能力的字符串，以便2个具有相同能力的不同用户将生成相同的能力字符串"?

SO: how can I get a string that represents the current user's abilities such that 2 different users with the same abilities will generate the same "ability string"?

我已经尝试过user.ability.inspect，但这不会为具有相同功能的不同用户生成相同的字符串

I've tried user.ability.inspect, but this doesn't produce the same string for different users who have the same abilities

推荐答案

针对CanCanCan进行了修订

从CanCanCan版本1.12(CanCan的社区延续)开始，Ability.new(user).permissions返回具有给定用户所有权限的哈希.

As of version 1.12 of CanCanCan (the community continuation of CanCan), Ability.new(user).permissions returns a hash with all permissions for the given user.

上一个答案(CanCan):

这可能有点复杂...但是在这里.

This might be a little complex...but here it goes..

如果将指定的用户传递到CanCan所需的Ability模型中，则可以使用instance_variable_get访问该用户角色的定义，然后将其分解为所需的任何字符串值.

If you pass the specified User into the Ability model required by CanCan, you can access the definition of that users role using instance_variable_get, and then break it down into whatever string values you want from there..

>> u=User.new(:role=>"admin")
>> a=Ability.new(u)
>> a.instance_variable_get("@rules").collect{ 
      |rule| rule.instance_variable_get("@actions").to_s
   }
=> ["read", "manage", "update"]

如果您想知道这些规则所基于的模型，可以访问@subjects实例变量以获取其名称.

if you want to know the models in which those rules are inflicted upon, you can access the @subjects instance variable to get its name..

这是我与(pp)一起工作的Ability的模型布局

here is the model layout for Ability from which I worked with (pp)

Ability:0x5b41dba @rules=[
  #<CanCan::Rule:0xc114739 
    @actions=[:read], 
    @base_behavior=true, 
    @conditions={}, 
    @match_all=false, 
    @block=nil, 
    @subjects=[
      User(role: string)]>, 
  #<CanCan::Rule:0x7ec40b92 
    @actions=[:manage], 
    @base_behavior=true, 
    @conditions={}, 
    @match_all=false, 
    @block=nil, 
    @subjects=[
      Encounter(id: integer)]>, 
  #<CanCan::Rule:0x55bf110c 
    @actions=[:update], 
    @base_behavior=true, 
    @conditions={:id=>4}, 
    @match_all=false, 
    @block=nil, 
    @subjects=[
      User(role: string)]>
]

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