Ruby on Rails creating multiple children in one parent form -

i have parent has multiple children. want when submit form, parent generated in parent model, , multiple records created in child model, 1 each child. when try , submit, following error:

 activerecord::associationtypemismatch in parentscontroller#create     child(#) expected, got array(#) 

when uncomment accepts_nested_attributes_for :children , change f.fields_for :children f.fields_for :children_attributes, different error:

  typeerror in parentscontroller#create      can't convert symbol integer 

i @ loss do. have checked out nested model forms railscasts, dealing generating children fields inside form, , learned railscasts didn't seem work. pretty doing builder.text_field :cname's in form wrong, i'm not aware of proper way it.

my code:

parent.rb

class parent < activerecord::base   has_many :children   #accepts_nested_attributes_for :children   attr_protected :id 

child.rb

class child < activerecord::base   belongs_to :parent   attr_protected :id 

_form.html.erb

<%= form_for @parent, :url => { :action => "create" } |f| %>   <%= f.text_field :pname %>   <%= f.fields_for :children |builder| %>     <%= builder.text_field :cname %>     <%= builder.text_field :cname %>     <%= builder.text_field :cname %>   <% end %>   <%= f.submit %> <% end %> 

params content:

{"utf8"=>"✓",  "authenticity_token"=>"fqq1kdnnxlxolfes9igio+akhjapch+2ltdda0twf7w=",  "parent"=>{"pname"=>"heman",  "child"=>{"cname"=>""}},  "commit"=>"create"} 

the problem here is generated form in html children using same "place" (same pair key/value) in params hash (using params[:parent][:child][:cname] pair). why there 1 param 'name' in 'child' node in params hash.

to avoid that, can use array input's name:

<input type="text" name="child[][cname]" /> <input type="text" name="child[][cname]" /> 

the params, when submitted, this:

params: {   child: [ { cname: 'blabla' }, { cname: 'bonjour' } ] } 

to desired result, in case:

<%= form_for @parent, :url => { :action => "create" } |f| %>   <%= f.text_field :pname %>    <%= text_field_tag "parent[children][][cname]" %>   <%= text_field_tag "parent[children][][cname]" %>   <%= text_field_tag "parent[children][][cname]" %>    <%= f.submit %> <% end %> 

should produce this:

{   "utf8"=>"✓",   "authenticity_token"=>"fqq1kdnnxlxolfes9igio+akhjapch+2ltdda0twf7w=",   "parent"=> {      "pname"=>"heman",     "children"=> [       { "cname"=>"sisisenior" },       { "cname"=>"bonjor" },       { "cname"=>"blabla" }     ]   },   "commit"=>"create"} 

so in controller, use this:

#parentscontroller def create   children_attributes = params[:parent].delete(:children) # takes off attributes of children   @parent = parent.create(params[:parent])    children_attributes.each |child_attributes|     child = @parent.children.create(child_attributes)   end end