Rails Autorisation avec CanCan Problème

Question

Sur mon application rails, j'ai implémenté AuthLogic et CanCan. Toutefois, en essayant de déterminer si l'utilisateur peut gérer un article (vérifie s'il est le propriétaire de l'article.user_id) avec CanCan, je rencontre des problèmes. Cela devrait être simple Je ne sais pas ce que je fais mal.

Articles has_many utilisateur

class Ability 
    include CanCan::Ability 

    def initialize(user) 
     user ||= User.new 

     can :read, :all 
     can :manage, Article do |article| 
      article.user_id == user.id 
     end 
    end   
end 

Je reçois l'erreur suivante lors du passage à/articles/index

undefined method `user' for #<Array:0x1035c5158> 
Extracted source (around line #15): 

12:   <td><%= article.created_at %></td> 
13:   <td><%= article.user.login %></td> 
14:   <td><%= link_to 'View', article %></td> 
15:  <% if can? :manage, article %> 
16:   <td><%= link_to 'Edit', edit_article_path(article) %></td> 
17:  <% end %> 
18:  <% if can? :manage, article %> 

app/models/ability.rb:9:in `try' 
app/models/ability.rb:9:in `initialize' 
cancan (1.3.4) lib/cancan/can_definition.rb:101:in `call' 
cancan (1.3.4) lib/cancan/can_definition.rb:101:in `call_block' 
cancan (1.3.4) lib/cancan/can_definition.rb:29:in `matches_conditions?' 
cancan (1.3.4) lib/cancan/ability.rb:54:in `can?' 
authlogic (2.1.6) lib/authlogic/session/password.rb:127:in `detect' 
cancan (1.3.4) lib/cancan/ability.rb:53:in `each' 
cancan (1.3.4) lib/cancan/ability.rb:53:in `detect' 
cancan (1.3.4) lib/cancan/ability.rb:53:in `can?' 
cancan (1.3.4) lib/cancan/controller_additions.rb:228:in `can?' 
actionpack (3.0.0) lib/abstract_controller/helpers.rb:55:in `send' 
actionpack (3.0.0) lib/abstract_controller/helpers.rb:55:in `can?' 
app/views/articles/_articles.html.erb:15:in `_app_views_articles__articles_html_erb__1624837607_2174751840_1924990' 
app/views/articles/_articles.html.erb:8:in `each' 
app/views/articles/_articles.html.erb:8:in `_app_views_articles__articles_html_erb__1624837607_2174751840_1924990' 
actionpack (3.0.0) lib/action_view/template.rb:135:in `send' 
actionpack (3.0.0) lib/action_view/template.rb:135:in `render' 
activesupport (3.0.0) lib/active_support/notifications.rb:54:in `instrument' 
actionpack (3.0.0) lib/action_view/template.rb:127:in `render' 
actionpack (3.0.0) lib/action_view/render/partials.rb:294:in `render_partial' 
actionpack (3.0.0) lib/action_view/render/partials.rb:223:in `render' 
activesupport (3.0.0) lib/active_support/notifications.rb:52:in `instrument' 
activesupport (3.0.0) lib/active_support/notifications/instrumenter.rb:21:in `instrument' 
activesupport (3.0.0) lib/active_support/notifications.rb:52:in `instrument' 
actionpack (3.0.0) lib/action_view/render/partials.rb:221:in `render' 
actionpack (3.0.0) lib/action_view/render/partials.rb:334:in `_render_partial' 
actionpack (3.0.0) lib/action_view/render/rendering.rb:31:in `render' 
app/views/articles/index.html.erb:5:in `_app_views_articles_index_html_erb___1319251192_2174766940_0' 
actionpack (3.0.0) lib/action_view/template.rb:135:in `send' 
actionpack (3.0.0) lib/action_view/template.rb:135:in `render' 
activesupport (3.0.0) lib/active_support/notifications.rb:54:in `instrument' 
actionpack (3.0.0) lib/action_view/template.rb:127:in `render' 
actionpack (3.0.0) lib/action_view/render/rendering.rb:59:in `_render_template' 
activesupport (3.0.0) lib/active_support/notifications.rb:52:in `instrument' 
activesupport (3.0.0) lib/active_support/notifications/instrumenter.rb:21:in `instrument' 
activesupport (3.0.0) lib/active_support/notifications.rb:52:in `instrument' 
actionpack (3.0.0) lib/action_view/render/rendering.rb:56:in `_render_template' 
actionpack (3.0.0) lib/action_view/render/rendering.rb:26:in `render' 
actionpack (3.0.0) lib/abstract_controller/rendering.rb:114:in `_render_template' 
actionpack (3.0.0) lib/abstract_controller/rendering.rb:108:in `render_to_body' 
actionpack (3.0.0) lib/action_controller/metal/renderers.rb:47:in `render_to_body' 
actionpack (3.0.0) lib/action_controller/metal/compatibility.rb:55:in `render_to_body' 
actionpack (3.0.0) lib/abstract_controller/rendering.rb:101:in `render_to_string' 
actionpack (3.0.0) lib/abstract_controller/rendering.rb:92:in `render' 
actionpack (3.0.0) lib/action_controller/metal/rendering.rb:17:in `render' 
actionpack (3.0.0) lib/action_controller/metal/instrumentation.rb:40:in `render' 
activesupport (3.0.0) lib/active_support/core_ext/benchmark.rb:5:in `ms' 
/opt/local/lib/ruby/1.8/benchmark.rb:308:in `realtime' 
activesupport (3.0.0) lib/active_support/core_ext/benchmark.rb:5:in `ms' 
actionpack (3.0.0) lib/action_controller/metal/instrumentation.rb:40:in `render' 
actionpack (3.0.0) lib/action_controller/metal/instrumentation.rb:78:in `cleanup_view_runtime' 
activerecord (3.0.0) lib/active_record/railties/controller_runtime.rb:15:in `cleanup_view_runtime' 
actionpack (3.0.0) lib/action_controller/metal/instrumentation.rb:39:in `render' 
actionpack (3.0.0) lib/action_controller/metal/implicit_render.rb:10:in `default_render' 
actionpack (3.0.0) lib/action_controller/metal/implicit_render.rb:5:in `send_action' 
actionpack (3.0.0) lib/abstract_controller/base.rb:150:in `process_action' 
actionpack (3.0.0) lib/action_controller/metal/rendering.rb:11:in `process_action' 
actionpack (3.0.0) lib/abstract_controller/callbacks.rb:18:in `process_action' 
activesupport (3.0.0) lib/active_support/callbacks.rb:440:in `_run__704842227__process_action__199225275__callbacks' 
activesupport (3.0.0) lib/active_support/callbacks.rb:409:in `send' 
activesupport (3.0.0) lib/active_support/callbacks.rb:409:in `_run_process_action_callbacks' 
activesupport (3.0.0) lib/active_support/callbacks.rb:93:in `send' 
activesupport (3.0.0) lib/active_support/callbacks.rb:93:in `run_callbacks' 
actionpack (3.0.0) lib/abstract_controller/callbacks.rb:17:in `process_action' 
actionpack (3.0.0) lib/action_controller/metal/instrumentation.rb:30:in `process_action' 
activesupport (3.0.0) lib/active_support/notifications.rb:52:in `instrument' 
activesupport (3.0.0) lib/active_support/notifications/instrumenter.rb:21:in `instrument' 
activesupport (3.0.0) lib/active_support/notifications.rb:52:in `instrument' 
actionpack (3.0.0) lib/action_controller/metal/instrumentation.rb:29:in `process_action' 
actionpack (3.0.0) lib/action_controller/metal/rescue.rb:17:in `process_action' 
actionpack (3.0.0) lib/abstract_controller/base.rb:119:in `process' 
actionpack (3.0.0) lib/abstract_controller/rendering.rb:40:in `process' 
actionpack (3.0.0) lib/action_controller/metal.rb:133:in `dispatch' 
actionpack (3.0.0) lib/action_controller/metal/rack_delegation.rb:14:in `dispatch' 
actionpack (3.0.0) lib/action_controller/metal.rb:173:in `action' 
actionpack (3.0.0) lib/action_dispatch/routing/route_set.rb:62:in `call' 
actionpack (3.0.0) lib/action_dispatch/routing/route_set.rb:62:in `dispatch' 
actionpack (3.0.0) lib/action_dispatch/routing/route_set.rb:27:in `call' 
rack-mount (0.6.13) lib/rack/mount/route_set.rb:148:in `call' 
rack-mount (0.6.13) lib/rack/mount/code_generation.rb:93:in `recognize' 
rack-mount (0.6.13) lib/rack/mount/code_generation.rb:68:in `optimized_each' 
rack-mount (0.6.13) lib/rack/mount/code_generation.rb:92:in `recognize' 
rack-mount (0.6.13) lib/rack/mount/route_set.rb:139:in `call' 
actionpack (3.0.0) lib/action_dispatch/routing/route_set.rb:492:in `call' 
actionpack (3.0.0) lib/action_dispatch/middleware/best_standards_support.rb:17:in `call' 
actionpack (3.0.0) lib/action_dispatch/middleware/head.rb:14:in `call' 
rack (1.2.1) lib/rack/methodoverride.rb:24:in `call' 
actionpack (3.0.0) lib/action_dispatch/middleware/params_parser.rb:21:in `call' 
actionpack (3.0.0) lib/action_dispatch/middleware/flash.rb:182:in `call' 
actionpack (3.0.0) lib/action_dispatch/middleware/session/abstract_store.rb:149:in `call' 
actionpack (3.0.0) lib/action_dispatch/middleware/cookies.rb:287:in `call' 
activerecord (3.0.0) lib/active_record/query_cache.rb:32:in `call' 
activerecord (3.0.0) lib/active_record/connection_adapters/abstract/query_cache.rb:28:in `cache' 
activerecord (3.0.0) lib/active_record/query_cache.rb:12:in `cache' 
activerecord (3.0.0) lib/active_record/query_cache.rb:31:in `call' 
activerecord (3.0.0) lib/active_record/connection_adapters/abstract/connection_pool.rb:355:in `call' 
actionpack (3.0.0) lib/action_dispatch/middleware/callbacks.rb:46:in `call' 
activesupport (3.0.0) lib/active_support/callbacks.rb:415:in `_run_call_callbacks' 
actionpack (3.0.0) lib/action_dispatch/middleware/callbacks.rb:44:in `call' 
rack (1.2.1) lib/rack/sendfile.rb:107:in `call' 
actionpack (3.0.0) lib/action_dispatch/middleware/remote_ip.rb:48:in `call' 
actionpack (3.0.0) lib/action_dispatch/middleware/show_exceptions.rb:46:in `call' 
railties (3.0.0) lib/rails/rack/logger.rb:13:in `call' 
rack (1.2.1) lib/rack/runtime.rb:17:in `call' 
activesupport (3.0.0) lib/active_support/cache/strategy/local_cache.rb:72:in `call' 
rack (1.2.1) lib/rack/lock.rb:11:in `call' 
rack (1.2.1) lib/rack/lock.rb:11:in `synchronize' 
rack (1.2.1) lib/rack/lock.rb:11:in `call' 
actionpack (3.0.0) lib/action_dispatch/middleware/static.rb:30:in `call' 
railties (3.0.0) lib/rails/application.rb:168:in `call' 
railties (3.0.0) lib/rails/application.rb:77:in `send' 
railties (3.0.0) lib/rails/application.rb:77:in `method_missing' 
railties (3.0.0) lib/rails/rack/log_tailer.rb:14:in `call' 
rack (1.2.1) lib/rack/content_length.rb:13:in `call' 
rack (1.2.1) lib/rack/handler/webrick.rb:52:in `service' 
/opt/local/lib/ruby/1.8/webrick/httpserver.rb:104:in `service' 
/opt/local/lib/ruby/1.8/webrick/httpserver.rb:65:in `run' 
/opt/local/lib/ruby/1.8/webrick/server.rb:173:in `start_thread' 
/opt/local/lib/ruby/1.8/webrick/server.rb:162:in `start' 
/opt/local/lib/ruby/1.8/webrick/server.rb:162:in `start_thread' 
/opt/local/lib/ruby/1.8/webrick/server.rb:95:in `start' 
/opt/local/lib/ruby/1.8/webrick/server.rb:92:in `each' 
/opt/local/lib/ruby/1.8/webrick/server.rb:92:in `start' 
/opt/local/lib/ruby/1.8/webrick/server.rb:23:in `start' 
/opt/local/lib/ruby/1.8/webrick/server.rb:82:in `start' 
rack (1.2.1) lib/rack/handler/webrick.rb:13:in `run' 
rack (1.2.1) lib/rack/server.rb:213:in `start' 
railties (3.0.0) lib/rails/commands/server.rb:65:in `start' 
railties (3.0.0) lib/rails/commands.rb:30 
railties (3.0.0) lib/rails/commands.rb:27:in `tap' 
railties (3.0.0) lib/rails/commands.rb:27 
script/rails:6:in `require' 
script/rails:6 

Voici mon avis:

<% if can? :manage, article %> 
    <td><%= link_to 'Edit', edit_article_path(article) %></td> 
<% end %> 
<% if can? :manage, article %> 
    <td><%= link_to 'Delete', article, :method => :delete %></td> 
<% end %> 

Voici mon contrôleur:

def index 
    @articles = Article.find(:all)  
    end 

Answer 1

Je ne sais pas exactement ce que votre cause de problème est sans trace, mais je trouve que je dois souvent vérifier nil lors de l'utilisation d'une valeur, par exemple dans votre exemple:

can :manage, Article do |article| 
    article && article.user_id == user.id 
end 

il semble que dans certaines situations, la argument bloc est nil

Selon http://github.com/ryanb/cancan/wiki/defining-abilities-with-hashes il peut y avoir un moyen plus propre:

can :manage, Article, :user_id => user.id 

Je voudrais essayer cette méthode sapins t, voyez comment vous allez.