我似乎无法想出这个......
据我所知，你必须为form_for视图帮助器提供一个实例变量，但是当我这样做时会引发错误......
对于一个简单的脚手架form_for我在wrong number of arguments (1 for 0)动作上提供模型实例时会出现参数错误new。
相关代码：
class AdminMessagesController < ApplicationController
before_filter :authenticate_user!
load_and_authorize_resource
def new
@admin_message = AdminMessage.new
logger.debug instance_variables
respond_to do |format|
format.html # new.html.erb
format.json { render json: @admin_message }
end
end
[:@_routes, :@_action_has_layout, :@_view_context_class, :@_headers, :@_status, :@_request, :@_response, :@_env, :@_prefixes, :@_lookup_context, :@_action_name, :@_response_body, :@_config, :@_params, :@current_user, :@current_ability, :@admin_message, :@_authorized]
class AdminMessage < ActiveRecord::Base
validates_presence_of :subject, :body
end
class Ability
include CanCan::Ability
def initialize(user)
# Define abilities for the passed in user here. For example:
user ||= User.new # guest user (not logged in)
if user.admin?
can :manage, :all
elsif user
can :manage, [Profile, BackgroundImage], :user_id => user.id
can :manage, Page, :profile => { :user_id => user.id }
can :read, [Profile]
else
can :read, [Profile]
end
- @title = "New Message"
= link_to 'Back', admin_messages_path, class: 'button'
%hr
%h1= @title
= render 'form'
= form_for @admin_message do |f|
-if @admin_message.errors.any?
#error_explanation
%h2= "#{pluralize(@admin_message.errors.count, "error")} prohibited this admin_message from being saved:"
%ul
- @admin_message.errors.full_messages.each do |msg|
%li= msg
.field
= f.label :subject
= f.text_field :subject
.field
= f.label :body
= f.text_area :body
.field
= f.label :send
= f.check_box :send
.actions
= f.submit 'Save'
resources :admin_messages
ArgumentError in Admin_messages#new
Showing /example/app/views/admin_messages/_form.html.haml where line #4 raised:
wrong number of arguments (1 for 0)
Extracted source (around line #4):
1: -# - puts self.public_methods
2: -# - puts self.instance_variables
3:
4: = form_for @admin_message do |f|
5: -if @admin_message.errors.any?
6: #error_explanation
7: %h2= "#{pluralize(@admin_message.errors.count, "error")} prohibited this admin_message from being saved:"
activerecord (3.1.2) lib/active_record/attribute_methods/read.rb:89:in `_send'
activerecord (3.1.2) lib/active_record/attribute_methods/primary_key.rb:8:in `to_key'
actionpack (3.1.2) lib/action_controller/record_identifier.rb:76:in `record_key_for_dom_id'
actionpack (3.1.2) lib/action_controller/record_identifier.rb:57:in `dom_id'
actionpack (3.1.2) lib/action_view/helpers/form_helper.rb:388:in `apply_form_for_options!'
actionpack (3.1.2) lib/action_view/helpers/form_helper.rb:365:in `form_for'
haml (3.1.3) lib/haml/helpers/action_view_mods.rb:182:in `form_for_with_haml'
haml (3.1.3) lib/haml/helpers/xss_mods.rb:132:in `form_for_with_haml_xss'
app/views/admin_messages/_form.html.haml:4:in `_app_views_admin_messages__form_html_haml__1654301332507974170_70145208768920'
actionpack (3.1.2) lib/action_view/template.rb:171:in `block in render'
activesupport (3.1.2) lib/active_support/notifications.rb:55:in `instrument'
actionpack (3.1.2) lib/action_view/template.rb:169:in `render'
actionpack (3.1.2) lib/action_view/renderer/partial_renderer.rb:256:in `render_partial'
actionpack (3.1.2) lib/action_view/renderer/partial_renderer.rb:228:in `block (2 levels) in render'
actionpack (3.1.2) lib/action_view/renderer/abstract_renderer.rb:33:in `block in instrument'
activesupport (3.1.2) lib/active_support/notifications.rb:53:in `block in instrument'
activesupport (3.1.2) lib/active_support/notifications/instrumenter.rb:21:in `instrument'
activesupport (3.1.2) lib/active_support/notifications.rb:53:in `instrument'
actionpack (3.1.2) lib/action_view/renderer/abstract_renderer.rb:33:in `instrument'
actionpack (3.1.2) lib/action_view/renderer/partial_renderer.rb:227:in `block in render'
actionpack (3.1.2) lib/action_view/renderer/abstract_renderer.rb:22:in `wrap_formats'
actionpack (3.1.2) lib/action_view/renderer/partial_renderer.rb:219:in `render'
actionpack (3.1.2) lib/action_view/renderer/renderer.rb:41:in `render_partial'
actionpack (3.1.2) lib/action_view/helpers/rendering_helper.rb:27:in `render'
haml (3.1.3) lib/haml/helpers/action_view_mods.rb:11:in `block in render_with_haml'
haml (3.1.3) lib/haml/helpers.rb:90:in `non_haml'
haml (3.1.3) lib/haml/helpers/action_view_mods.rb:11:in `render_with_haml'
app/views/admin_messages/new.html.haml:6:in `_app_views_admin_messages_new_html_haml__1382734216418550338_70145179834340'
actionpack (3.1.2) lib/action_view/template.rb:171:in `block in render'
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actionpack (3.1.2) lib/action_view/renderer/abstract_renderer.rb:33:in `block in instrument'
activesupport (3.1.2) lib/active_support/notifications.rb:53:in `block in instrument'
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actionpack (3.1.2) lib/action_view/renderer/abstract_renderer.rb:33:in `instrument'
actionpack (3.1.2) lib/action_view/renderer/template_renderer.rb:39:in `block in render_template'
actionpack (3.1.2) lib/action_view/renderer/template_renderer.rb:47:in `render_with_layout'
actionpack (3.1.2) lib/action_view/renderer/template_renderer.rb:38:in `render_template'
actionpack (3.1.2) lib/action_view/renderer/template_renderer.rb:12:in `block in render'
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actionpack (3.1.2) lib/abstract_controller/rendering.rb:114:in `render_to_body'
actionpack (3.1.2) lib/action_controller/metal/renderers.rb:30:in `render_to_body'
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activesupport (3.1.2) lib/active_support/core_ext/benchmark.rb:5:in `block in ms'
/Users/victorstan/.rvm/rubies/ruby-1.9.2-p290/lib/ruby/1.9.1/benchmark.rb:310:in `realtime'
activesupport (3.1.2) lib/active_support/core_ext/benchmark.rb:5:in `ms'
actionpack (3.1.2) lib/action_controller/metal/instrumentation.rb:40:in `block in render'
actionpack (3.1.2) lib/action_controller/metal/instrumentation.rb:78:in `cleanup_view_runtime'
activerecord (3.1.2) lib/active_record/railties/controller_runtime.rb:24:in `cleanup_view_runtime'
actionpack (3.1.2) lib/action_controller/metal/instrumentation.rb:39:in `render'
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actionpack (3.1.2) lib/action_controller/metal/mime_responds.rb:268:in `block in retrieve_response_from_mimes'
actionpack (3.1.2) lib/action_controller/metal/mime_responds.rb:195:in `call'
actionpack (3.1.2) lib/action_controller/metal/mime_responds.rb:195:in `respond_to'
app/controllers/admin_messages_controller.rb:33:in `new'
actionpack (3.1.2) lib/action_controller/metal/implicit_render.rb:4:in `send_action'
actionpack (3.1.2) lib/abstract_controller/base.rb:167:in `process_action'
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actionpack (3.1.2) lib/abstract_controller/callbacks.rb:18:in `block in process_action'
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activesupport (3.1.2) lib/active_support/callbacks.rb:386:in `_run_process_action_callbacks'
activesupport (3.1.2) lib/active_support/callbacks.rb:81:in `run_callbacks'
actionpack (3.1.2) lib/abstract_controller/callbacks.rb:17:in `process_action'
actionpack (3.1.2) lib/action_controller/metal/rescue.rb:17:in `process_action'
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activesupport (3.1.2) lib/active_support/notifications.rb:53:in `block in instrument'
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activesupport (3.1.2) lib/active_support/notifications.rb:53:in `instrument'
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actionpack (3.1.2) lib/action_controller/metal/params_wrapper.rb:201:in `process_action'
activerecord (3.1.2) lib/active_record/railties/controller_runtime.rb:18:in `process_action'
actionpack (3.1.2) lib/abstract_controller/base.rb:121:in `process'
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actionpack (3.1.2) lib/action_controller/metal/rack_delegation.rb:14:in `dispatch'
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rack (1.3.5) lib/rack/sendfile.rb:101:in `call'
actionpack (3.1.2) lib/action_dispatch/middleware/remote_ip.rb:48:in `call'
actionpack (3.1.2) lib/action_dispatch/middleware/show_exceptions.rb:47:in `call'
railties (3.1.2) lib/rails/rack/logger.rb:13:in `call'
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rack (1.3.5) lib/rack/runtime.rb:17:in `call'
activesupport (3.1.2) lib/active_support/cache/strategy/local_cache.rb:72:in `call'
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actionpack (3.1.2) lib/action_dispatch/middleware/static.rb:53:in `call'
railties (3.1.2) lib/rails/engine.rb:456:in `call'
rack (1.3.5) lib/rack/content_length.rb:14:in `call'
railties (3.1.2) lib/rails/rack/log_tailer.rb:14:in `call'
rack (1.3.5) lib/rack/handler/webrick.rb:59:in `service'
/Users/victorstan/.rvm/rubies/ruby-1.9.2-p290/lib/ruby/1.9.1/webrick/httpserver.rb:111:in `service'
/Users/victorstan/.rvm/rubies/ruby-1.9.2-p290/lib/ruby/1.9.1/webrick/httpserver.rb:70:in `run'
/Users/victorstan/.rvm/rubies/ruby-1.9.2-p290/lib/ruby/1.9.1/webrick/server.rb:183:in `block in start_thread'
如果我尝试检查控制器#new操作中的@admin_message var，则错误消息会更改为指示控制器而不是视图中的错误...
ArgumentError in AdminMessagesController#new
wrong number of arguments (1 for 0)
如果我将puts @admin_message.inspect添加到控制器操作new
答案 0 :(得分：1)
故事的道德：不要将send用作表格列名称！