ArgumentError in StaticPages#home - ruby-on-rails

Question

I noob in Rails. I use rails 4.2.4. I have a problem with my contact form. I have an error: First argument in form cannot contain nil or be empty on the 3 line of this code (contact_form.html.erb):
<div class="all-banners-width">
<figure class="green-background">
<%= form_for #contact_form do |f| %>
<p>
<%= f.label :name %><br>
<%= f.text_field :name %>
</p>
<p>
<%= f.label :phone %><br>
<%= f.text_field :phone %>
</p>
<p>
<%= f.label :email %><br>
<%= f.text_field :email %>
</p>
<p>
<%= f.label :text %><br>
<%= f.text_field :text %>
</p>
<p>
<%= f.submit %>
</p>
<% end %>
</figure>
</div>
My contact_form_controller.rb is:
class ContactFormController < ApplicationController
def contact_form
#contact_form = ContactForm.new
end
def create
#contact_form = ContactForm.new(contact_form_params)
#contact_form.save
redirect_to root_path, notice: "Saved"
end
private
def contact_form_params
params.require(:contact_form).permit(:name, :phone, :email, :text)
end
end
My DB migration file is:
class CreateContactForms < ActiveRecord::Migration
def change
create_table :contact_forms do |t|
t.string :name
t.string :phone
t.string :email
t.string :text
t.timestamps null: false
end
end
end
If I change 3rd line from contact_form.html.erb to the next:
<%= form_for :contact_form do |f| %>
then I have not an error, but anyway contact form does not work and there are not any errors I can see.
Can somebody help me? I have not idea, where is problem.

Answer 1

You miss action new in controller:
def new
#contact_form = ContactForm.new
end
your template is rendered with #contact_form = nil.