Question

There must be an easy answer to this question, but I’m still unable to get it working.

I have a Ruby On Rails app that allows the user to manage projects with a database (create, update, show, edit, destroy, …, etc.). For example, when the user edits a projects, she/he is taken to a page, like http://:3000/projects/3/edit where she/he can modify entries the the form there. Notice the user is editing project 3 in this example.

To edit a project, the user click this button

<td><%= button_to 'Edit', { :action => "edit", :id => project }, :method => :get %></td>

which call this method

# GET /projects/1/edit
def edit
  @project = Project.find(params[:id])
end

and that works fine.

However, I added another method call updateFields, so that when a field is modified, a javascript function called updateFields is run and calls an AJAX request that modifies other related fields in the form. The following is an excerpt from updateFields:

<script language="JavaScript" type="text/javascript">
function updateFields(){
    $.ajax({
        url: "<%= update_fields_projects_url %>",
        data: {
            project_year: $('.project_year_class').val(),
            project_type: $('.project_type_class').val(),

            <snip>

        }
    });
}
</script>

In the controller, I can then get all the info I need in params array, like the following:

# PUT /projects/1
# PUT /projects/1.json

def update_fields

  @project = Project.find(params[:project])
  @project_year = params[:project_year]
  @project_type = params[:project_type]

  <snip>

  respond_to do |format|
    if @project.update_attributes(params[:project])
      format.js
      format.html
    else
      format.html { render :action => "update" }
      format.json { render :json => @project.errors, :status => :unprocessable_entity }
    end
  end
end

The problem I have is that I’m not able to update the form, and on the server, I see the following error messages

ActiveRecord::RecordNotFound (Couldn't find Project without an ID):
app/controllers/projects_controller.rb:101:in `update_fields'

Rendered /var/lib/gems/1.8/gems/actionpack-3.2.9/lib/action_dispatch/middleware/templates/rescues/_trace.erb (1.5ms)
Rendered /var/lib/gems/1.8/gems/actionpack-3.2.9/lib/action_dispatch/middleware/templates/rescues/_request_and_response.erb (2.2ms)
Rendered /var/lib/gems/1.8/gems/actionpack-3.2.9/lib/action_dispatch/middleware/templates/rescues/diagnostics.erb within rescues/layout (10.8ms)

If I specify the project id directly, all works fine

@project = Project.find(3)

My question is how do I get that id passed in params to the controller by the javascript function in the same way than project_year and project_type? in this example, it is 3, but it will be different for every project because it is assigned when the project is created.

Update1

<%= form_for(@project, :html => {:name => "ProjectInfo"}) do |f| %>

  <input type=button id=project_info_button_id value="Show Details" onclick="showHideDiv('project_info_id','project_info_button_id');">

  <div class="form input", id='project_info_id', style='display:none'>
    <% concat "Project Year" %>
    <%= f.text_field :ProjectYear, {:class=>"project_year_class", :Size=>6, :style=>"text-align:right"} %>

    <snip>

  <% end %>
<% end %>

Answer 1

You need to pass the project id in the data section of the ajax request:

<script language="JavaScript" type="text/javascript">
function updateFields(){
    $.ajax({
        url: "<%= update_fields_projects_url %>",
        data: {
            project_year: $('.project_year_class').val(),
            project_type: $('.project_type_class').val(),
            id: <%= @project.id %>,
            <snip>

        }
    });
}
</script>