Create multiple new objects in one page

Rails
1

I’m trying to make a view with one form for each instance of a model
(ferms) in which a user can update some attributes (in this case I’m
calling them kinetics)

Ferm
has_many :kinetics

Kinetic
belongs_to :ferm

In my KineticsController I have before_filter :get_ferms

private
def get_ferms
@ferms = Ferms.find(:all)
end
In my new action in the KineticsController I have

@kinetic = Kinetic.new

And that’s where I get stuck…

Here is what I have in the views/kinetics/new.html.erb:

<% @ferms.each do |ferm| %>

Name :<%= ferm.name %>

<% form_for(ferm, @kinetic) do |f| %>

<Something<%= f.text_field :something %>

<% end %> <% end %>

But it’s broken… Any ideas on what to change/do differently to
create the page with multiple forms?? Thanks for any help,

SH

2

watch the railscasts on complex forms:

Part 1 #73 Complex Forms Part 1 - RailsCasts
Part 2 #74 Complex Forms Part 2 - RailsCasts
Part 3 #75 Complex Forms Part 3 - RailsCasts

3

I think I’m close to figuring it out… below are the relevant app
details, any suggestions are greatly appreciated.

Models:

class Ferm < AR::Base
has_many :kinetics, :dependent => :destroy
end

class Kinetic < AR::Base
belongs_to :ferm
end

Controllers

class KineticsController < AC
def new
@kinetics = []
@ferms = Ferm.find(:all)
for ferm in @ferms
kinetic = ferm.kinetics.build(params[:kinetic])
@kinetics << kinetic
end
end

def create
@kinetics = params[:kinetic]
for kinetic in @kinetics
new_kinetic = Kinetic.new(params[:kinetic])
new_kinetic.save
end
redirect_to :controller => ‘ferms’, :action => ‘index’
end

View

Kinetics/new.html.erb

<% form_tag(:action => 'create') do -%>

<%= render :partial => ‘kinetic’, :collection => @kinetics %>
<%= submit_tag ‘Enter Brix & Temp’ %>
<% end -%>

Kinetics/_kinetic.html.erb

<table>
Tank <%=h kinetic.ferm.tank %> Blend <%=h kinetic.ferm.blend_number %> Brix <%= text_field(:kinetic, :brix, :name => "kinetic[][brix]") %> Temp <%= text_field(:kinetic, :temp, :name => "kinetic[][temp]") %> <%= hidden_field_tag(:kinetic, :ferm_id, :name => "kinetic[] [ferm_id]", :value => kinetic.ferm.id) %>

…

What this gives me in the params hash is: parameters:
{“commit”=>“Enter Brix & Temp”, “kinetic”=[{“ferm_id”=>[1],
“brix”=>[25], “temp”=>[70]},{“ferm_id”=>[2], “brix”=>[28],
“temp”=>[80]}] and I get the error: NoMethodError in
KineticsController#create … undefined method `stringify_keys!’ for
#Array:0x198b1dc.

I understand that stringify_keys! is expecting a hash and getting an
array and that’s why it’s complaining… am I instantiating the
@kinetics variable incorrectly in KineticsController#new to handle
this array? Should I reconfigure the form to submit a hash of the
kinetics (like: {“1”=>[{“ferm_id”=>“1”, “brix”=>“25”,
“temp”=>“70”}]})?

Any help is appreciated… thanks in advance.

SH

4

figured it out… my problem was in the new action in the
KineticsController. Here is what has worked:

def new
@kinetics = params[:kinetic]
@kinetics.each do |k|
new_kinetic = Kinetic.new
new_kinetic.brix = k[“brix”]
new_kinetic.temp = k[“temp”]
new_kinetic.ferm_id = k[“ferm_id”]
new_kinetic.save
end
end

I’m sure there are several better ways to do this, please chime in if
anyone wants to share an improvement to this method.

SH

5

What this gives me in the params hash is: parameters:
{“commit”=>“Enter Brix & Temp”, “kinetic”=[{“ferm_id”=>[1],
“brix”=>[25], “temp”=>[70]},{“ferm_id”=>[2], “brix”=>[28],
“temp”=>[80]}] and I get the error: NoMethodError in
KineticsController#create … undefined method `stringify_keys!’ for
#Array:0x198b1dc.

Oops typo above: the array looks like :

“kinetic”=[{“ferm_id”=>“1”, “brix”=>“25”, “temp”=>“70”},
{“ferm_id”=>“2”, “brix”=>“28”, “temp”=>“80”}]

without square brackets around the values.