ruby on rails - undefined method `map' for nil:NilClass when submitting the selection tag -


i new rails. , have question when submitted form. when submitted form, shows

nomethoderror in foods#new, showing ..../new.html.erb line #16 raised: undefined method `map' nil:nilclass

while line 16 is:

<%= select_tag(:category_id, options_for_select(@categories), :prompt => "please select") %>

i little confused method map, need add create action?

here new action

def new @food = food.new     @categories = category.all.map{|c| [ c.name, c.id ] } end

and here create action 

def create @food = food.new(food_params) @food.category_id = params[:category_id]  if @food.save   flash[:success] = "adding successful!"   redirect_to @food else   render 'new' end end  def food_params params.require(:food).permit(:name, :price, :category_id, :description, :picture) end

would me solve problem?

i see 1 issue in create method.

in event @food.save == false, you're not building 

@categories = category.all.map{|c| [ c.name, c.id ] }

before 

render 'new'

so form isn't getting @categories info needs build select statement.


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