ruby on rails 3 - accepts_nested_attributes_for triggering a 'Can't mass-assign protected attributes warning -

firstly first time have ever tried use accepts_nested_attributes_for, still learning , have missed small.

so have setup , follow example doing accepts_nested_attributes_for keep getting activemodel::massassignmentsecurity::error @ /reports can't mass-assign protected attributes: deployment

and can't figure out why, grateful code below:

report model:

class report < activerecord::base   attr_accessible :name, :weekending, :visable, :deployments_attributes   has_many :deployments, dependent: :destroy   accepts_nested_attributes_for :deployments, allow_destroy: true end 

deployments model:

class deployment < activerecord::base   attr_accessible :deployment_comments, :deployment_name, :environment, :report_id   belongs_to :report end 

report/new.html.erb

<%= form_for (@report) |f| %>    <%= render 'shared/error_messages' %>   <h4>reprot detials</h4>   <%= f.label "report written by: " %>  <%= f.text_field :name %><br>   <%= f.label "weekending: " %>  <%= f.text_field :weekending %><br>   <%= f.label "visable: " %>  <%= f.text_field :visable %><br>    <%= f.fields_for :deployment |builder| %>     <%= render 'reports/forms/deployment_fields', f: builder %>   <% end %><br><br>     <%= f.submit class: "btn btn-large btn-primary" %>  <% end %> 

report/forms/_deployment_fields.html.erb

<h4>deployments</h4>   <%= f.label :deployment_name, "name of deployment:" %><br />   <%= f.text_field :deployment_name %><br />   <%= f.label :environment, "environment of deployment:" %><br />   <%= f.text_field :environment %><br />   <%= f.label :deployment_comments, "deployment comments:" %><br />   <%= f.text_area :deployment_comments %><br /> 

reports controller:

class reportscontroller < applicationcontroller    def index     @reports = report.paginate(:page   => params[:page],                                :per_page => 20,                                :order => 'weekending desc')   end    def show     @report = report.find(params[:id])   end    def new     @report = report.new   end    def create     @report = report.new(params[:report])     if @report.save       redirect_to reports_url     else       render 'new'     end   end 

db migrations:

timestamp_create_deployments.rb

class createdeployments < activerecord::migration   def change     create_table :deployments |t|       t.string :environment       t.integer :report_id       t.string :deployment_name       t.string :deployment_comments        t.timestamps     end     add_index :deployments, [:report_id]   end end 

timestap_create_reports.rb

class createreports < activerecord::migration   def change     create_table :reports |t|       t.date :weekending, :null => false       t.string :name, :null => false       t.boolean :visable, :default => false, :null => false        t.timestamps     end   end end 

so figured out, once changed

<%= f.fields_for :deployment |builder| %> 

to

<%= f.fields_for :deployments |builder| %> 

i found deployments fields didnt show, added

@report.deployments.build 

to new method of report controller!

i'll need figure out if need update/edit method or not?