Rails undefined method 'map' for nil:NilClass - ruby-on-rails-3

Question

I receive this message when i attempt to create a new record from a nested form. The strange thing is when I just backspace to the previous page(page with the 'create' button) and hit 'create' again, the record is created. So I am not sure why it won't create the record the first time as I don't change the create method in my controller during the first and second button press. Anyone experience this before that can help me understand why this is happening would be great.
Models
class Benefit < ActiveRecord::Base
belongs_to :account
has_many :employee_benefits
has_many :benefit_plans, :inverse_of => :benefit
belongs_to :benefit_coverage_period
belongs_to :benefit_type_id, :class_name => "LookupTable", :foreign_key => "benefit_type"
attr_accessible :account_id, :active, :attachment, :automatic_rollover, :id, :benefit_id, :benefit_type_id
attr_accessible :benefit_coverage_id, :benefit_type, :is_pretax, :benefit_coverage_period_id
attr_accessible :description, :enrollable, :link, :name, :has_plans, :has_custom_amount, :benefit_plans_attributes
validates_format_of :link, :message => "Please enter a valid URL", :with => /^(http|https):\/\/[a-z0-9]+([\-\.]{1}[a-z0-9]+)*\.[a-z]{2,5}(:[0-9]{1,5})?(\/.*)?$/ix
accepts_nested_attributes_for :benefit_plans, allow_destroy: true
end
class BenefitPlan < ActiveRecord::Base
belongs_to :benefit, :inverse_of => :benefit_plans
validates_presence_of :benefit
has_many :employee_benefits
has_many :benefit_coverages
attr_accessible :benefit_id, :description, :name, :benefit_coverages_attributes, :link, :attachment
accepts_nested_attributes_for :benefit_coverages, allow_destroy: true
end
class BenefitCoverage < ActiveRecord::Base
belongs_to :benefit_plan
has_many :employee_benefits
belongs_to :name_id, :class_name => "LookupTable", :foreign_key => "name"
attr_accessible :benefit_plan_id, :name, :paycheck_deduction, :percentage_split, :total_cost
accepts_nested_attributes_for :employee_benefits
end
Controller
def new
#benefit = Benefit.new
#benefit_coverage_periods = #account.benefit_coverage_periods
1.times { #benefit.benefit_plans.build(:name => 'Default Plan') }
#lookup_tables = LookupTable.where(:active => :true).find_all_by_group(30) || []
#lookup_tables1 = LookupTable.where(:active => :true).find_all_by_group(31) || []
end
def create
#benefit = Benefit.new(params[:benefit])
#lookup_tables = LookupTable.where(:active => :true).find_all_by_group(30) || []
#lookup_tables1 = LookupTable.where(:active => :true).find_all_by_group(31) || []
#benefit_coverage_periods = #account.benefit_coverage_periods
if #benefit.save
redirect_to benefits_path, :notice => 'Benefit was successfully created.'
else
render :action => "new"
end
View
= form_for #benefit, :html => { :class => "form-horizontal" }, :validate => true do |f|
= f.hidden_field :account_id, :value => #account.id
.control-group
= f.label :name, :class => "control-label"
.controls
= f.text_field :name, :class => "text_field"
.control-group
= f.label :benefit_type, "Benefit Type", :class => "control-label"
.controls
= f.collection_select :benefit_type, #lookup_tables1, :id, :title, :prompt => true
...
Error
NoMethodError - undefined method `map' for nil:NilClass:
15:00:09 web.1 | actionpack (3.2.14) lib/action_view/helpers/form_options_helper.rb:364:in `options_from_collection_for_select'
15:00:09 web.1 | actionpack (3.2.14) lib/action_view/helpers/form_options_helper.rb:600:in `to_collection_select_tag'
15:00:09 web.1 | actionpack (3.2.14) lib/action_view/helpers/form_options_helper.rb:191:in `collection_select'
15:00:09 web.1 | actionpack (3.2.14) lib/action_view/helpers/form_options_helper.rb:646:in `collection_select'
15:00:09 web.1 | client_side_validations (3.2.6) lib/client_side_validations/action_view/form_builder.rb:77:in `collection
_select_with_client_side_validations'
15:00:09 web.1 | app/views/benefits/_form.html.haml:10:in `block in _app_views_benefits__form_html_haml___5210787370672092
58_70323180464100'
15:00:09 web.1 | haml (4.1.0.beta.1) lib/haml/helpers/action_view_mods.rb:132:in `block (2 levels) in form_for_with_haml'
15:00:09 web.1 | haml (4.1.0.beta.1) lib/haml/helpers.rb:284:in `with_tabs'
15:00:09 web.1 | haml (4.1.0.beta.1) lib/haml/helpers/action_view_mods.rb:132:in `block in form_for_with_haml'
15:00:09 web.1 | actionpack (3.2.14) lib/action_view/helpers/capture_helper.rb:40:in `block in capture'
15:00:09 web.1 | actionpack (3.2.14) lib/action_view/helpers/capture_helper.rb:187:in `with_output_buffer'
...

Answer 1

The stack trace tells you everything you need to know to figure this out. Let's learn to fish!
First of all "Undefined method X for Y" means "You tried to call a method X on object Y, but Y doesn't have that method". In this case, you're trying to call map on nil, and nil doesn't implement map. So we're looking for a place that we call map, and then we're going to try to figure out why the object we're calling map on could be nil.
15:00:09 web.1 | app/views/benefits/_form.html.haml:10:in `block in _app_views_benefits__form_html_haml___5210787370672092
This tells you to look on line 10 in _form.html.haml. That's where you're going to fix the issue. However, the issue happens in lib/action_view/helpers/form_options_helper.rb:364 in the options_from_collection_for_select method. It's a pretty good guess that that corresponds to this line:
= f.collection_select :benefit_type, #lookup_tables1, :id, :title, :prompt => true
If you look at the source there, you can see what it's calling. Working backwards from the top of the stack trace:
https://github.com/rails/rails/blob/v3.2.14/actionpack/lib/action_view/helpers/form_options_helper.rb#L364
https://github.com/rails/rails/blob/v3.2.14/actionpack/lib/action_view/helpers/form_options_helper.rb#L600
https://github.com/rails/rails/blob/v3.2.14/actionpack/lib/action_view/helpers/form_options_helper.rb#L191
https://github.com/rails/rails/blob/v3.2.14/actionpack/lib/action_view/helpers/form_options_helper.rb#L646
We can see that it's calling map on the collection that is passed in. By following the stack trace back to the FormBuilder#collection_select method, we can determine exactly which parameter this is - #lookup_tables1, in your case.
Now, #lookup_tables1 is set in your new action, but it's not set in your create action, when you render action: :new. From this, we can surmise that the first time you try to save your Benefit record, the save fails and returns false. Your second branch is run there, which attempts to render the new template, but because you didn't set #lookup_tables1, the collection_select fails as it's attempting to create a select box from a nil collection.
So, you have two tasks:
Populate your #lookup_tables1 from your create method before you call render action: :new
Figure out why your Benefit record is failing to save, and fix that.
As an aside, you should update Rails to the the latest 3.x series (3.2.19 as of right now). 3.2.14 has several vulnerabilities that have been since fixed.