¿Por qué obtengo un método indefinido 'join' para nil: NilClass error?

I have this code in my "index.html.erb" file in my project:

<h1>Listing businesses</h1>

<table>
<tr>
    <th>Index</th>
    <th>Name</th>
    <th>Phone Number</th>
    <th>Suite</th>
    <th>Address</th>
    <th>City</th>
<th>Province</th>
<th>Postal Code</th>
<th>Fax</th>
    <th>Latitude</th>
    <th>Longitude</th>
    <th>Website</th>
    </tr>

<% count = 0 %>
<% @businesses.each do |business| %>
<!--<%=business.inspect %> <br> <br>-->
<%count = count.to_i + 1 %> 
<tr>
    <td><%= count %></td>
    <td><%= business.name %></td>
    <td><%= business.phone %></td>
    <td><%= business.suite %></td>
    <td><%= business.address %></td>
    <td><%= business.city %></td>
    <td><%= business.province %></td>
    <td><%= business.phone %></td>
    <td><%= business.postalcode %></td>
    <td><%= business.fax %></td>
    <td><%= business.latitude %></td>
    <td><%= business.longitude %></td>
    <td><%= business.website %></td>
    <td><%= link_to 'Show', business %></td>
    <td><%= link_to 'Edit', edit_business_path(business) %></td>
    <td><%= link_to 'Destroy', user, confirm: 'Are you sure?', method: :delete %></td>
</tr>
<% end %>
</table>

When I go to this url:

http://localhost:3000/businesses/

Recibo este error:

NoMethodError in Businesses#index

Showing /Users/AM/Documents/RailsWS/cmdLineWS/Directory/app/views/businesses/index.html.erb where line #37 raised:

undefined method `join' for nil:NilClass
Extracted source (around line #37):

34:     <td><%= business.latitude %></td>
35:     <td><%= business.longitude %></td>
36:     <td><%= business.website %></td>
37:     <td><%= link_to 'Show', business %></td>
38:     <td><%= link_to 'Edit', edit_business_path(business) %></td>
39:     <td><%= link_to 'Destroy', user, confirm: 'Are you sure?', method: :delete %></td>
40:   </tr>
Rails.root: /Users/AM/Documents/RailsWS/cmdLineWS/Directory

¿Tienes idea de lo que está pasando?

Aquí está la pila de llamadas completa:

activemodel (3.2.1) lib/active_model/conversion.rb:52:in `to_param'
actionpack (3.2.1) lib/action_dispatch/routing/route_set.rb:417:in `block in <class:Generator>'
journey (1.0.3) lib/journey/formatter.rb:31:in `call'
journey (1.0.3) lib/journey/formatter.rb:31:in `block (2 levels) in generate'
journey (1.0.3) lib/journey/formatter.rb:30:in `each'
journey (1.0.3) lib/journey/formatter.rb:30:in `block in generate'
journey (1.0.3) lib/journey/formatter.rb:58:in `match_route'
journey (1.0.3) lib/journey/formatter.rb:16:in `generate'
actionpack (3.2.1) lib/action_dispatch/routing/route_set.rb:510:in `generate'
actionpack (3.2.1) lib/action_dispatch/routing/route_set.rb:551:in `generate'
actionpack (3.2.1) lib/action_dispatch/routing/route_set.rb:576:in `url_for'
actionpack (3.2.1) lib/action_dispatch/routing/url_for.rb:148:in `url_for'
actionpack (3.2.1) lib/action_view/helpers/url_helper.rb:107:in `url_for'
actionpack (3.2.1) lib/action_dispatch/routing/route_set.rb:202:in `business_path'
app/views/businesses/index.html.erb:37:in `block in _app_views_businesses_index_html_erb___1138300221443858101_2152537040'
app/views/businesses/index.html.erb:20:in `each'
app/views/businesses/index.html.erb:20:in `_app_views_businesses_index_html_erb___1138300221443858101_2152537040'
actionpack (3.2.1) lib/action_view/template.rb:143:in `block in render'
activesupport (3.2.1) lib/active_support/notifications.rb:125:in `instrument'
actionpack (3.2.1) lib/action_view/template.rb:141:in `render'
actionpack (3.2.1) lib/action_view/renderer/template_renderer.rb:41:in `block (2 levels) in render_template'
actionpack (3.2.1) lib/action_view/renderer/abstract_renderer.rb:38:in `block in instrument'
activesupport (3.2.1) lib/active_support/notifications.rb:123:in `block in instrument'
activesupport (3.2.1) lib/active_support/notifications/instrumenter.rb:20:in `instrument'
activesupport (3.2.1) lib/active_support/notifications.rb:123:in `instrument'
actionpack (3.2.1) lib/action_view/renderer/abstract_renderer.rb:38:in `instrument'
actionpack (3.2.1) lib/action_view/renderer/template_renderer.rb:40:in `block in render_template'
actionpack (3.2.1) lib/action_view/renderer/template_renderer.rb:48:in `render_with_layout'
actionpack (3.2.1) lib/action_view/renderer/template_renderer.rb:39:in `render_template'
actionpack (3.2.1) lib/action_view/renderer/template_renderer.rb:12:in `render'
actionpack (3.2.1) lib/action_view/renderer/renderer.rb:36:in `render_template'
actionpack (3.2.1) lib/action_view/renderer/renderer.rb:17:in `render'
actionpack (3.2.1) lib/abstract_controller/rendering.rb:109:in `_render_template'
actionpack (3.2.1) lib/action_controller/metal/streaming.rb:225:in `_render_template'
actionpack (3.2.1) lib/abstract_controller/rendering.rb:103:in `render_to_body'
actionpack (3.2.1) lib/action_controller/metal/renderers.rb:28:in `render_to_body'
actionpack (3.2.1) lib/action_controller/metal/compatibility.rb:50:in `render_to_body'
actionpack (3.2.1) lib/abstract_controller/rendering.rb:88:in `render'
actionpack (3.2.1) lib/action_controller/metal/rendering.rb:16:in `render'
actionpack (3.2.1) lib/action_controller/metal/instrumentation.rb:40:in `block (2 levels) in render'
activesupport (3.2.1) lib/active_support/core_ext/benchmark.rb:5:in `block in ms'
/Users/AM/.rvm/rubies/ruby-1.9.2-p290/lib/ruby/1.9.1/benchmark.rb:310:in `realtime'
activesupport (3.2.1) lib/active_support/core_ext/benchmark.rb:5:in `ms'
actionpack (3.2.1) lib/action_controller/metal/instrumentation.rb:40:in `block in render'
actionpack (3.2.1) lib/action_controller/metal/instrumentation.rb:83:in `cleanup_view_runtime'
activerecord (3.2.1) lib/active_record/railties/controller_runtime.rb:24:in `cleanup_view_runtime'
actionpack (3.2.1) lib/action_controller/metal/instrumentation.rb:39:in `render'
actionpack (3.2.1) lib/action_controller/metal/implicit_render.rb:10:in `default_render'
actionpack (3.2.1) lib/action_controller/metal/mime_responds.rb:268:in `block in retrieve_response_from_mimes'
actionpack (3.2.1) lib/action_controller/metal/mime_responds.rb:195:in `call'
actionpack (3.2.1) lib/action_controller/metal/mime_responds.rb:195:in `respond_to'
app/controllers/businesses_controller.rb:5:in `index'
actionpack (3.2.1) lib/action_controller/metal/implicit_render.rb:4:in `send_action'
actionpack (3.2.1) lib/abstract_controller/base.rb:167:in `process_action'
actionpack (3.2.1) lib/action_controller/metal/rendering.rb:10:in `process_action'
actionpack (3.2.1) lib/abstract_controller/callbacks.rb:18:in `block in process_action'
activesupport (3.2.1) lib/active_support/callbacks.rb:414:in `_run__4378774651029744650__process_action__1974792849221574797__callbacks'
activesupport (3.2.1) lib/active_support/callbacks.rb:405:in `__run_callback'
activesupport (3.2.1) lib/active_support/callbacks.rb:385:in `_run_process_action_callbacks'
activesupport (3.2.1) lib/active_support/callbacks.rb:81:in `run_callbacks'
actionpack (3.2.1) lib/abstract_controller/callbacks.rb:17:in `process_action'
actionpack (3.2.1) lib/action_controller/metal/rescue.rb:29:in `process_action'
actionpack (3.2.1) lib/action_controller/metal/instrumentation.rb:30:in `block in process_action'
activesupport (3.2.1) lib/active_support/notifications.rb:123:in `block in instrument'
activesupport (3.2.1) lib/active_support/notifications/instrumenter.rb:20:in `instrument'
activesupport (3.2.1) lib/active_support/notifications.rb:123:in `instrument'
actionpack (3.2.1) lib/action_controller/metal/instrumentation.rb:29:in `process_action'
actionpack (3.2.1) lib/action_controller/metal/params_wrapper.rb:205:in `process_action'
activerecord (3.2.1) lib/active_record/railties/controller_runtime.rb:18:in `process_action'
actionpack (3.2.1) lib/abstract_controller/base.rb:121:in `process'
actionpack (3.2.1) lib/abstract_controller/rendering.rb:45:in `process'
actionpack (3.2.1) lib/action_controller/metal.rb:203:in `dispatch'
actionpack (3.2.1) lib/action_controller/metal/rack_delegation.rb:14:in `dispatch'
actionpack (3.2.1) lib/action_controller/metal.rb:246:in `block in action'
actionpack (3.2.1) lib/action_dispatch/routing/route_set.rb:66:in `call'
actionpack (3.2.1) lib/action_dispatch/routing/route_set.rb:66:in `dispatch'
actionpack (3.2.1) lib/action_dispatch/routing/route_set.rb:30:in `call'
journey (1.0.3) lib/journey/router.rb:68:in `block in call'
journey (1.0.3) lib/journey/router.rb:56:in `each'
journey (1.0.3) lib/journey/router.rb:56:in `call'
actionpack (3.2.1) lib/action_dispatch/routing/route_set.rb:589:in `call'
actionpack (3.2.1) lib/action_dispatch/middleware/best_standards_support.rb:17:in `call'
rack (1.4.1) lib/rack/etag.rb:23:in `call'
rack (1.4.1) lib/rack/conditionalget.rb:25:in `call'
actionpack (3.2.1) lib/action_dispatch/middleware/head.rb:14:in `call'
actionpack (3.2.1) lib/action_dispatch/middleware/params_parser.rb:21:in `call'
actionpack (3.2.1) lib/action_dispatch/middleware/flash.rb:242:in `call'
rack (1.4.1) lib/rack/session/abstract/id.rb:205:in `context'
rack (1.4.1) lib/rack/session/abstract/id.rb:200:in `call'
actionpack (3.2.1) lib/action_dispatch/middleware/cookies.rb:338:in `call'
activerecord (3.2.1) lib/active_record/query_cache.rb:64:in `call'
activerecord (3.2.1) lib/active_record/connection_adapters/abstract/connection_pool.rb:443:in `call'
actionpack (3.2.1) lib/action_dispatch/middleware/callbacks.rb:28:in `block in call'
activesupport (3.2.1) lib/active_support/callbacks.rb:405:in `_run__539745845193235082__call__2953064504705011211__callbacks'
activesupport (3.2.1) lib/active_support/callbacks.rb:405:in `__run_callback'
activesupport (3.2.1) lib/active_support/callbacks.rb:385:in `_run_call_callbacks'
activesupport (3.2.1) lib/active_support/callbacks.rb:81:in `run_callbacks'
actionpack (3.2.1) lib/action_dispatch/middleware/callbacks.rb:27:in `call'
actionpack (3.2.1) lib/action_dispatch/middleware/reloader.rb:65:in `call'
actionpack (3.2.1) lib/action_dispatch/middleware/remote_ip.rb:31:in `call'
actionpack (3.2.1) lib/action_dispatch/middleware/debug_exceptions.rb:16:in `call'
actionpack (3.2.1) lib/action_dispatch/middleware/show_exceptions.rb:56:in `call'
railties (3.2.1) lib/rails/rack/logger.rb:26:in `call_app'
railties (3.2.1) lib/rails/rack/logger.rb:16:in `call'
actionpack (3.2.1) lib/action_dispatch/middleware/request_id.rb:22:in `call'
rack (1.4.1) lib/rack/methodoverride.rb:21:in `call'
rack (1.4.1) lib/rack/runtime.rb:17:in `call'
activesupport (3.2.1) lib/active_support/cache/strategy/local_cache.rb:72:in `call'
rack (1.4.1) lib/rack/lock.rb:15:in `call'
actionpack (3.2.1) lib/action_dispatch/middleware/static.rb:53:in `call'
railties (3.2.1) lib/rails/engine.rb:479:in `call'
railties (3.2.1) lib/rails/application.rb:220:in `call'
rack (1.4.1) lib/rack/content_length.rb:14:in `call'
railties (3.2.1) lib/rails/rack/log_tailer.rb:14:in `call'
rack (1.4.1) lib/rack/handler/webrick.rb:59:in `service'
/Users/AM/.rvm/rubies/ruby-1.9.2-p290/lib/ruby/1.9.1/webrick/httpserver.rb:111:in `service'
/Users/AM/.rvm/rubies/ruby-1.9.2-p290/lib/ruby/1.9.1/webrick/httpserver.rb:70:in `run'
/Users/AM/.rvm/rubies/ruby-1.9.2-p290/lib/ruby/1.9.1/webrick/server.rb:183:in `block in start_thread'

Model for the app is file called business.rb it contains this:

class Business < ActiveRecord::Base
  establish_connection "Listings_development"
end

preguntado el 09 de marzo de 12 a las 22:03

Usted anula to_key in your model? What does business.to_key ¿regreso? -

It'd be great if you could post the Model code for Business :) -

@summea the model code of the business has been added to the post -

@Andrew Marshall I haven't overridden the business.to_key method. I just tested the output for that method, its empty. -

1 Respuestas

Since your table does not seem to have a primary key, read the Guía de migración de rieles and write one to add the id columna a su mesa.

def change
  add_column :business, :id, :primary_key
end

Como se describe in the documentation of the to_param Método, vuelve nil if your object has not yet been persisted.

This is because a link to an object that is not in the database is actually a broken link. Make sure your object is being saved before attempting to link to it.


<td><%= link_to 'Show', business %></td>

That's likely to be the problem. You must link to an URL, not to a model. Use a helper to obtain one that refers to the object:

<td><%= link_to 'Show', business_path(business) %></td>

The same problem will occur here, I suppose:

<td><%= link_to 'Destroy', user, ... %></td>

You should replace that line with:

<td><%= link_to 'Destroy', destroy_user_path(user), ... %></td>

respondido 10 mar '12, 00:03

No that doesnt seem to be the problem - rey bandido

@banditKing, can you post the full call stack? - mateo moreira

@banditKing: please don't edit somebody else's answer to add the call stack. Please edit your question and add it there instead. - Lucas Woodward

You can actually pass link_to a model object. There's even an ejemplo en los documentos te vinculaste :). - Andrew Marshall

So I found out the problem might be somehow similar to this post: stackoverflow.com/questions/3124290/… Im trying to figure it out now... - rey bandido

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