Rails AJAX 500错误

Question

I'm completing a tutorial on Rails - however the tutorial was written with Rails 2, and as I have Rails 3 I'm having to convert everything over.

I've got a Google Map, and when you click on it, you should have a pop-up appear with a new marker and a form for entering the data into. When I click the map, the marker is appearing, but no form for entering data. Any help would be much appreciated!

I'm guessing it has something to do with the ajax?? When I click anywhere on the map to try and enter new data, the web console is giving me a 500 internal server error. No idea where I'm going wrong!

Here's the controller code for the 'new' action:

def new
  @incident = Incident.new

  respond_to do |format|
    format.html {
      @incident.latitude=params['latitude']
      @incident.longitude=params['longitude']
      render :partial=>'new', :locals=>{:incident=>@incident}
    }
    format.xml  { render :xml => @incident }
  end
end

The index view:

<h1>Listing incidents</h1>

<%= render(:partial=>"map", :locals=>{:data=>"/incidents.xml",
  :full_page=>true, :show_action=>'show', :new_action=>'new'}) %>

And the 'new' partial:

<h1>New incident</h1>
<% form_for(incident, :update=>'map_info'), :remote => true do |f| %>
 <p>
    <%= f.label :mountain %> <%= f.text_field :mountain %>
 </p>
 <%= f.hidden_field :latitude %>
 <%= f.hidden_field :longitude %>
 <p>
   <%= f.label :when %> <%= f.datetime_select :when %>
 </p>
 <p>
   <%= f.label :title %> <%= f.text_field :title %>
 </p>
 <p>
   <%= f.label :description %><br/>
   <%= f.text_area :description, :rows=>3 %>
 </p>
 <p>
   <%= f.submit "Create" %>
 </p>
<% end %>

Here's the stack trace (when I load the page, then click on the map for a new incident):

Started GET "/assets/application.js?body=1" for 127.0.0.1 at 2012-09-27 14:35:18
 +0100
Served asset /application.js - 304 Not Modified (173ms)
[2012-09-27 14:35:18] WARN  Could not determine content-length of response body.
 Set content-length of the response or set Response#chunked = true


Started GET "/assets/prototype.js?body=1" for 127.0.0.1 at 2012-09-27 14:35:18 +
0100
Served asset /prototype.js - 304 Not Modified (0ms)
[2012-09-27 14:35:18] WARN  Could not determine content-length of response body.
 Set content-length of the response or set Response#chunked = true


Started GET "/incidents.xml" for 127.0.0.1 at 2012-09-27 14:35:19 +0100
Processing by IncidentsController#index as XML
  ←[1m←[35mIncident Load (1.0ms)←[0m  SELECT "incidents".* FROM "incidents"
  Rendered text template (0.0ms)
Completed 200 OK in 945ms (Views: 184.0ms | ActiveRecord: 1.0ms)
[2012-09-27 14:35:20] WARN  Could not determine content-length of response body.
 Set content-length of the response or set Response#chunked = true


Started GET "/incidents/new?latitude=42.50990089326676&longitude=-99.4921875" fo
r 127.0.0.1 at 2012-09-27 14:35:43 +0100
Processing by IncidentsController#new as JS
  Parameters: {"latitude"=>"42.50990089326676", "longitude"=>"-99.4921875"}
ERROR: compiling _app_views_incidents__new_html_erb___613446974_25808988 RAISED
c:/Ruby193/incidents/app/views/incidents/_new.html.erb:2: syntax error, unexpect
ed ',', expecting keyword_end
'); form_for(incident, :update=>'map_info'), :remote => true do |f|
                                            ^
c:/Ruby193/incidents/app/views/incidents/_new.html.erb:23: syntax error, unexpec
ted keyword_ensure, expecting $end
Function body:           def _app_views_incidents__new_html_erb___613446974_2580
8988(local_assigns, output_buffer)
            _old_virtual_path, @virtual_path = @virtual_path, "incidents/_new";_
old_output_buffer = @output_buffer;incident = local_assigns[:incident];new = loc
al_assigns[:new];;@output_buffer = output_buffer || ActionView::OutputBuffer.new
;@output_buffer.safe_concat('<h1>New incident</h1>
'); form_for(incident, :update=>'map_info'), :remote => true do |f|
@output_buffer.safe_concat(' <p>
    ');@output_buffer.append= ( f.label :mountain );@output_buffer.safe_concat('
 ');@output_buffer.append= ( f.text_field :mountain );@output_buffer.safe_concat
('
');@output_buffer.safe_concat('  </p>
  ');@output_buffer.append= ( f.hidden_field :latitude );@output_buffer.safe_con
cat('
');@output_buffer.safe_concat('  ');@output_buffer.append= ( f.hidden_field :lon
gitude );@output_buffer.safe_concat('
');@output_buffer.safe_concat('  <p>
    ');@output_buffer.append= ( f.label :when );@output_buffer.safe_concat(' ');
@output_buffer.append= ( f.datetime_select :when );@output_buffer.safe_concat('
');@output_buffer.safe_concat('  </p>
  <p>
    ');@output_buffer.append= ( f.label :title );@output_buffer.safe_concat(' ')
;@output_buffer.append= ( f.text_field :title );@output_buffer.safe_concat('
');@output_buffer.safe_concat('  </p>
  <p>
    ');@output_buffer.append= ( f.label :description );@output_buffer.safe_conca
t('<br/>
    ');@output_buffer.append= ( f.text_area :description, :rows=>3 );@output_buf
fer.safe_concat('
');@output_buffer.safe_concat('  </p>
  <p>
    ');@output_buffer.append= ( f.submit "Create" );@output_buffer.safe_concat('

');@output_buffer.safe_concat('  </p>
'); end
@output_buffer.to_s
          ensure
            @virtual_path, @output_buffer = _old_virtual_path, _old_output_buffe
r
          end

Backtrace: C:/Ruby193/lib/ruby/gems/1.9.1/gems/actionpack-3.2.4.rc1/lib/action_v
iew/template.rb:297:in `module_eval'
C:/Ruby193/lib/ruby/gems/1.9.1/gems/actionpack-3.2.4.rc1/lib/action_view/templat
e.rb:297:in `compile'
C:/Ruby193/lib/ruby/gems/1.9.1/gems/actionpack-3.2.4.rc1/lib/action_view/templat
e.rb:244:in `block in compile!'
<internal:prelude>:10:in `synchronize'
C:/Ruby193/lib/ruby/gems/1.9.1/gems/actionpack-3.2.4.rc1/lib/action_view/templat
e.rb:232:in `compile!'
C:/Ruby193/lib/ruby/gems/1.9.1/gems/actionpack-3.2.4.rc1/lib/action_view/templat
e.rb:144:in `block in render'
C:/Ruby193/lib/ruby/gems/1.9.1/gems/activesupport-3.2.4.rc1/lib/active_support/n
otifications.rb:125:in `instrument'
C:/Ruby193/lib/ruby/gems/1.9.1/gems/actionpack-3.2.4.rc1/lib/action_view/templat
e.rb:143:in `render'
C:/Ruby193/lib/ruby/gems/1.9.1/gems/actionpack-3.2.4.rc1/lib/action_view/rendere
r/partial_renderer.rb:265:in `render_partial'
C:/Ruby193/lib/ruby/gems/1.9.1/gems/actionpack-3.2.4.rc1/lib/action_view/rendere
r/partial_renderer.rb:238:in `block in render'
C:/Ruby193/lib/ruby/gems/1.9.1/gems/actionpack-3.2.4.rc1/lib/action_view/rendere
r/abstract_renderer.rb:38:in `block in instrument'
C:/Ruby193/lib/ruby/gems/1.9.1/gems/activesupport-3.2.4.rc1/lib/active_support/n
otifications.rb:123:in `block in instrument'
C:/Ruby193/lib/ruby/gems/1.9.1/gems/activesupport-3.2.4.rc1/lib/active_support/n
otifications/instrumenter.rb:20:in `instrument'
C:/Ruby193/lib/ruby/gems/1.9.1/gems/activesupport-3.2.4.rc1/lib/active_support/n
otifications.rb:123:in `instrument'
C:/Ruby193/lib/ruby/gems/1.9.1/gems/actionpack-3.2.4.rc1/lib/action_view/rendere
r/abstract_renderer.rb:38:in `instrument'
C:/Ruby193/lib/ruby/gems/1.9.1/gems/actionpack-3.2.4.rc1/lib/action_view/rendere
r/partial_renderer.rb:237:in `render'
C:/Ruby193/lib/ruby/gems/1.9.1/gems/actionpack-3.2.4.rc1/lib/action_view/rendere
r/renderer.rb:41:in `render_partial'
C:/Ruby193/lib/ruby/gems/1.9.1/gems/actionpack-3.2.4.rc1/lib/action_view/rendere
r/renderer.rb:15:in `render'
C:/Ruby193/lib/ruby/gems/1.9.1/gems/actionpack-3.2.4.rc1/lib/abstract_controller
/rendering.rb:110:in `_render_template'
C:/Ruby193/lib/ruby/gems/1.9.1/gems/actionpack-3.2.4.rc1/lib/action_controller/m
etal/streaming.rb:225:in `_render_template'
C:/Ruby193/lib/ruby/gems/1.9.1/gems/actionpack-3.2.4.rc1/lib/abstract_controller
/rendering.rb:103:in `render_to_body'
C:/Ruby193/lib/ruby/gems/1.9.1/gems/actionpack-3.2.4.rc1/lib/action_controller/m
etal/renderers.rb:28:in `render_to_body'
C:/Ruby193/lib/ruby/gems/1.9.1/gems/actionpack-3.2.4.rc1/lib/action_controller/m
etal/compatibility.rb:50:in `render_to_body'
C:/Ruby193/lib/ruby/gems/1.9.1/gems/actionpack-3.2.4.rc1/lib/abstract_controller
/rendering.rb:88:in `render'
C:/Ruby193/lib/ruby/gems/1.9.1/gems/actionpack-3.2.4.rc1/lib/action_controller/m
etal/rendering.rb:16:in `render'
C:/Ruby193/lib/ruby/gems/1.9.1/gems/actionpack-3.2.4.rc1/lib/action_controller/m
etal/instrumentation.rb:40:in `block (2 levels) in render'
C:/Ruby193/lib/ruby/gems/1.9.1/gems/activesupport-3.2.4.rc1/lib/active_support/c
ore_ext/benchmark.rb:5:in `block in ms'
C:/Ruby193/lib/ruby/1.9.1/benchmark.rb:295:in `realtime'
C:/Ruby193/lib/ruby/gems/1.9.1/gems/activesupport-3.2.4.rc1/lib/active_support/c
ore_ext/benchmark.rb:5:in `ms'
C:/Ruby193/lib/ruby/gems/1.9.1/gems/actionpack-3.2.4.rc1/lib/action_controller/m
etal/instrumentation.rb:40:in `block in render'
C:/Ruby193/lib/ruby/gems/1.9.1/gems/actionpack-3.2.4.rc1/lib/action_controller/m
etal/instrumentation.rb:83:in `cleanup_view_runtime'
C:/Ruby193/lib/ruby/gems/1.9.1/gems/activerecord-3.2.4.rc1/lib/active_record/rai
lties/controller_runtime.rb:24:in `cleanup_view_runtime'
C:/Ruby193/lib/ruby/gems/1.9.1/gems/actionpack-3.2.4.rc1/lib/action_controller/m
etal/instrumentation.rb:39:in `render'
c:/Ruby193/incidents/app/controllers/incidents_controller.rb:24:in `block (2 lev
els) in new'
C:/Ruby193/lib/ruby/gems/1.9.1/gems/actionpack-3.2.4.rc1/lib/action_controller/m
etal/mime_responds.rb:196:in `call'
C:/Ruby193/lib/ruby/gems/1.9.1/gems/actionpack-3.2.4.rc1/lib/action_controller/m
etal/mime_responds.rb:196:in `respond_to'
c:/Ruby193/incidents/app/controllers/incidents_controller.rb:20:in `new'
C:/Ruby193/lib/ruby/gems/1.9.1/gems/actionpack-3.2.4.rc1/lib/action_controller/m
etal/implicit_render.rb:4:in `send_action'
C:/Ruby193/lib/ruby/gems/1.9.1/gems/actionpack-3.2.4.rc1/lib/abstract_controller
/base.rb:167:in `process_action'
C:/Ruby193/lib/ruby/gems/1.9.1/gems/actionpack-3.2.4.rc1/lib/action_controller/m
etal/rendering.rb:10:in `process_action'
C:/Ruby193/lib/ruby/gems/1.9.1/gems/actionpack-3.2.4.rc1/lib/abstract_controller
/callbacks.rb:18:in `block in process_action'
C:/Ruby193/lib/ruby/gems/1.9.1/gems/activesupport-3.2.4.rc1/lib/active_support/c
allbacks.rb:414:in `_run__322942522__process_action__447782570__callbacks'
C:/Ruby193/lib/ruby/gems/1.9.1/gems/activesupport-3.2.4.rc1/lib/active_support/c
allbacks.rb:405:in `__run_callback'
C:/Ruby193/lib/ruby/gems/1.9.1/gems/activesupport-3.2.4.rc1/lib/active_support/c
allbacks.rb:385:in `_run_process_action_callbacks'
C:/Ruby193/lib/ruby/gems/1.9.1/gems/activesupport-3.2.4.rc1/lib/active_support/c
allbacks.rb:81:in `run_callbacks'
C:/Ruby193/lib/ruby/gems/1.9.1/gems/actionpack-3.2.4.rc1/lib/abstract_controller
/callbacks.rb:17:in `process_action'
C:/Ruby193/lib/ruby/gems/1.9.1/gems/actionpack-3.2.4.rc1/lib/action_controller/m
etal/rescue.rb:29:in `process_action'
C:/Ruby193/lib/ruby/gems/1.9.1/gems/actionpack-3.2.4.rc1/lib/action_controller/m
etal/instrumentation.rb:30:in `block in process_action'
C:/Ruby193/lib/ruby/gems/1.9.1/gems/activesupport-3.2.4.rc1/lib/active_support/n
otifications.rb:123:in `block in instrument'
C:/Ruby193/lib/ruby/gems/1.9.1/gems/activesupport-3.2.4.rc1/lib/active_support/n
otifications/instrumenter.rb:20:in `instrument'
C:/Ruby193/lib/ruby/gems/1.9.1/gems/activesupport-3.2.4.rc1/lib/active_support/n
otifications.rb:123:in `instrument'
C:/Ruby193/lib/ruby/gems/1.9.1/gems/actionpack-3.2.4.rc1/lib/action_controller/m
etal/instrumentation.rb:29:in `process_action'
C:/Ruby193/lib/ruby/gems/1.9.1/gems/actionpack-3.2.4.rc1/lib/action_controller/m
etal/params_wrapper.rb:206:in `process_action'
C:/Ruby193/lib/ruby/gems/1.9.1/gems/activerecord-3.2.4.rc1/lib/active_record/rai
lties/controller_runtime.rb:18:in `process_action'
C:/Ruby193/lib/ruby/gems/1.9.1/gems/actionpack-3.2.4.rc1/lib/abstract_controller
/base.rb:121:in `process'
C:/Ruby193/lib/ruby/gems/1.9.1/gems/actionpack-3.2.4.rc1/lib/abstract_controller
/rendering.rb:45:in `process'
C:/Ruby193/lib/ruby/gems/1.9.1/gems/actionpack-3.2.4.rc1/lib/action_controller/m
etal.rb:203:in `dispatch'
C:/Ruby193/lib/ruby/gems/1.9.1/gems/actionpack-3.2.4.rc1/lib/action_controller/m
etal/rack_delegation.rb:14:in `dispatch'
C:/Ruby193/lib/ruby/gems/1.9.1/gems/actionpack-3.2.4.rc1/lib/action_controller/m
etal.rb:246:in `block in action'
C:/Ruby193/lib/ruby/gems/1.9.1/gems/actionpack-3.2.4.rc1/lib/action_dispatch/rou
ting/route_set.rb:73:in `call'
C:/Ruby193/lib/ruby/gems/1.9.1/gems/actionpack-3.2.4.rc1/lib/action_dispatch/rou
ting/route_set.rb:73:in `dispatch'
C:/Ruby193/lib/ruby/gems/1.9.1/gems/actionpack-3.2.4.rc1/lib/action_dispatch/rou
ting/route_set.rb:36:in `call'
C:/Ruby193/lib/ruby/gems/1.9.1/gems/journey-1.0.4/lib/journey/router.rb:68:in `b
lock in call'
C:/Ruby193/lib/ruby/gems/1.9.1/gems/journey-1.0.4/lib/journey/router.rb:56:in `e
ach'
C:/Ruby193/lib/ruby/gems/1.9.1/gems/journey-1.0.4/lib/journey/router.rb:56:in `c
all'
C:/Ruby193/lib/ruby/gems/1.9.1/gems/actionpack-3.2.4.rc1/lib/action_dispatch/rou
ting/route_set.rb:600:in `call'
C:/Ruby193/lib/ruby/gems/1.9.1/gems/actionpack-3.2.4.rc1/lib/action_dispatch/mid
dleware/best_standards_support.rb:17:in `call'
C:/Ruby193/lib/ruby/gems/1.9.1/gems/rack-1.4.1/lib/rack/etag.rb:23:in `call'
C:/Ruby193/lib/ruby/gems/1.9.1/gems/rack-1.4.1/lib/rack/conditionalget.rb:25:in
`call'
C:/Ruby193/lib/ruby/gems/1.9.1/gems/actionpack-3.2.4.rc1/lib/action_dispatch/mid
dleware/head.rb:14:in `call'
C:/Ruby193/lib/ruby/gems/1.9.1/gems/actionpack-3.2.4.rc1/lib/action_dispatch/mid
dleware/params_parser.rb:21:in `call'
C:/Ruby193/lib/ruby/gems/1.9.1/gems/actionpack-3.2.4.rc1/lib/action_dispatch/mid
dleware/flash.rb:238:in `call'
C:/Ruby193/lib/ruby/gems/1.9.1/gems/rack-1.4.1/lib/rack/session/abstract/id.rb:2
05:in `context'
C:/Ruby193/lib/ruby/gems/1.9.1/gems/rack-1.4.1/lib/rack/session/abstract/id.rb:2
00:in `call'
C:/Ruby193/lib/ruby/gems/1.9.1/gems/actionpack-3.2.4.rc1/lib/action_dispatch/mid
dleware/cookies.rb:338:in `call'
C:/Ruby193/lib/ruby/gems/1.9.1/gems/activerecord-3.2.4.rc1/lib/active_record/que
ry_cache.rb:64:in `call'
C:/Ruby193/lib/ruby/gems/1.9.1/gems/activerecord-3.2.4.rc1/lib/active_record/con
nection_adapters/abstract/connection_pool.rb:473:in `call'
C:/Ruby193/lib/ruby/gems/1.9.1/gems/actionpack-3.2.4.rc1/lib/action_dispatch/mid
dleware/callbacks.rb:28:in `block in call'
C:/Ruby193/lib/ruby/gems/1.9.1/gems/activesupport-3.2.4.rc1/lib/active_support/c
allbacks.rb:405:in `_run__711941801__call__927210605__callbacks'
C:/Ruby193/lib/ruby/gems/1.9.1/gems/activesupport-3.2.4.rc1/lib/active_support/c
allbacks.rb:405:in `__run_callback'
C:/Ruby193/lib/ruby/gems/1.9.1/gems/activesupport-3.2.4.rc1/lib/active_support/c
allbacks.rb:385:in `_run_call_callbacks'
C:/Ruby193/lib/ruby/gems/1.9.1/gems/activesupport-3.2.4.rc1/lib/active_support/c
allbacks.rb:81:in `run_callbacks'
C:/Ruby193/lib/ruby/gems/1.9.1/gems/actionpack-3.2.4.rc1/lib/action_dispatch/mid
dleware/callbacks.rb:27:in `call'
C:/Ruby193/lib/ruby/gems/1.9.1/gems/actionpack-3.2.4.rc1/lib/action_dispatch/mid
dleware/reloader.rb:65:in `call'
C:/Ruby193/lib/ruby/gems/1.9.1/gems/actionpack-3.2.4.rc1/lib/action_dispatch/mid
dleware/remote_ip.rb:31:in `call'
C:/Ruby193/lib/ruby/gems/1.9.1/gems/actionpack-3.2.4.rc1/lib/action_dispatch/mid
dleware/debug_exceptions.rb:16:in `call'
C:/Ruby193/lib/ruby/gems/1.9.1/gems/actionpack-3.2.4.rc1/lib/action_dispatch/mid
dleware/show_exceptions.rb:56:in `call'
C:/Ruby193/lib/ruby/gems/1.9.1/gems/railties-3.2.4.rc1/lib/rails/rack/logger.rb:
26:in `call_app'
C:/Ruby193/lib/ruby/gems/1.9.1/gems/railties-3.2.4.rc1/lib/rails/rack/logger.rb:
16:in `call'
C:/Ruby193/lib/ruby/gems/1.9.1/gems/actionpack-3.2.4.rc1/lib/action_dispatch/mid
dleware/request_id.rb:22:in `call'
C:/Ruby193/lib/ruby/gems/1.9.1/gems/rack-1.4.1/lib/rack/methodoverride.rb:21:in
`call'
C:/Ruby193/lib/ruby/gems/1.9.1/gems/rack-1.4.1/lib/rack/runtime.rb:17:in `call'
C:/Ruby193/lib/ruby/gems/1.9.1/gems/activesupport-3.2.4.rc1/lib/active_support/c
ache/strategy/local_cache.rb:72:in `call'
C:/Ruby193/lib/ruby/gems/1.9.1/gems/rack-1.4.1/lib/rack/lock.rb:15:in `call'
C:/Ruby193/lib/ruby/gems/1.9.1/gems/actionpack-3.2.4.rc1/lib/action_dispatch/mid
dleware/static.rb:62:in `call'
C:/Ruby193/lib/ruby/gems/1.9.1/gems/railties-3.2.4.rc1/lib/rails/engine.rb:479:i
n `call'
C:/Ruby193/lib/ruby/gems/1.9.1/gems/railties-3.2.4.rc1/lib/rails/application.rb:
220:in `call'
C:/Ruby193/lib/ruby/gems/1.9.1/gems/rack-1.4.1/lib/rack/content_length.rb:14:in
`call'
C:/Ruby193/lib/ruby/gems/1.9.1/gems/railties-3.2.4.rc1/lib/rails/rack/log_tailer
.rb:17:in `call'
C:/Ruby193/lib/ruby/gems/1.9.1/gems/rack-1.4.1/lib/rack/handler/webrick.rb:59:in
 `service'
C:/Ruby193/lib/ruby/1.9.1/webrick/httpserver.rb:138:in `service'
C:/Ruby193/lib/ruby/1.9.1/webrick/httpserver.rb:94:in `run'
C:/Ruby193/lib/ruby/1.9.1/webrick/server.rb:191:in `block in start_thread'
  Rendered incidents/_new.html.erb (169.0ms)
Completed 500 Internal Server Error in 178ms

ActionView::Template::Error (c:/Ruby193/incidents/app/views/incidents/_new.html.
erb:2: syntax error, unexpected ',', expecting keyword_end
'); form_for(incident, :update=>'map_info'), :remote => true do |f|
                                            ^
c:/Ruby193/incidents/app/views/incidents/_new.html.erb:23: syntax error, unexpec
ted keyword_ensure, expecting $end):
    1: <h1>New incident</h1>
    2: <% form_for(incident, :update=>'map_info'), :remote => true do |f| %>
    3:  <p>
    4:     <%= f.label :mountain %> <%= f.text_field :mountain %>
    5:   </p>
  app/controllers/incidents_controller.rb:24:in `block (2 levels) in new'
  app/controllers/incidents_controller.rb:20:in `new'


  Rendered C:/Ruby193/lib/ruby/gems/1.9.1/gems/actionpack-3.2.4.rc1/lib/action_d
ispatch/middleware/templates/rescues/_trace.erb (5.0ms)
  Rendered C:/Ruby193/lib/ruby/gems/1.9.1/gems/actionpack-3.2.4.rc1/lib/action_d
ispatch/middleware/templates/rescues/_request_and_response.erb (2.0ms)
  Rendered C:/Ruby193/lib/ruby/gems/1.9.1/gems/actionpack-3.2.4.rc1/lib/action_d
ispatch/middleware/templates/rescues/template_error.erb within rescues/layout (1
38.0ms)

Answer 1

According to the error:

Its the "," from in front of the :remote => true, behind the form_for(incident, :update=>'map_info'). Remove it

Ok so lets recode it. Try:

<%= form_for incidents_url, :remote => true do |f| %>

You have to add a new file in incidents called new.js.erb (incidents/new.js.erb). Normally it would be called create.js.erb, but you're using the new action, not create.

Inside that file you write the jQuery code that updated the div.

$(".class_name_of_div").prepend("<%= @incident.which_ever_attribute_you_want %>");

Also you might want to change your controller a bit:

def new
  @incident = Incident.new
  @incident.latitude = params[:latitude]
  @incident.longitude = params[:longitude]
  @incident.save

  respond_to do |format|
    format.html
    format.js
  end
end

Change the partial too:

<%= render 'incidents/map', :incident => @incident %>

Tell me how it goes.