NoMethodError (undefined method `name' for nil:NilClass) - ruby-on-rails

Question

I am trying to upload images without gem to a model called "Course Classifications", before I was using the gem "Paperclip".
Rails Version is Rails 3.0.10
When I am trying to create a "Course Classification", I get the following error:
undefined method `name 'for nil: NilClass
I suppose it must be something regarding the image that I am trying to upload, because when I do not load an image, the model is created normally.
according to my console the error is in the line of the method 'create' 'if #course_clasification.save'
What can be?
The 'puts' throw me the following:
"PARAMS: {\"name\"=>\"Prueba12312\", \"description\"=>\"\", \"status\"=>\"1\", \"picture\"=>#<ActionDispatch::Http::UploadedFile:0x0055ffb16c36d8 #original_filename=\"Selección_250.png\", #content_type=\"image/png\", #headers=\"Content-Disposition: form-data; name=\\\"course_clasification[picture]\\\"; filename=\\\"Selecci\\xC3\\xB3n_250.png\\\"\\r\\nContent-Type: image/png\\r\\n\", #tempfile=#<Tempfile:/tmp/RackMultipart20210722-21412-xnr47e>>}"
"NAME: Prueba12312"
My code is the following:
Controller:
def create
#course_clasification = CourseClasification.new(params[:course_clasification])
p "PARAMS: #{params[:course_clasification]}"
if params[:course_clasification].present?
file = params[:course_clasification][:picture]
File.open(Rails.root.join('public','uploads', file.original_filename), 'wb') do |f|
f.write(file.read)
end
end
respond_to do |format|
if #course_clasification.save
format.html { redirect_to(course_clasifications_path, :notice => 'Classification was created') }
format.xml { render :xml => #course_clasification, :status => :created, :location => #course_clasification }
else
format.html { render :action => "new" }
format.xml { render :xml => #course_clasification.errors, :status => :unprocessable_entity }
end
end
end
def upload
uploaded_io = params.require(:course_clasification).permit(:picture)
File.open(Rails.root.join('public','uploads',uploaded_io.original_filename), 'wb') do |file|
file.write(uploaded_io.read)
end
end
Model:
class CourseClasification < ActiveRecord::Base
has_many :courses
has_many :enrollments
validates :name, presence: true
=begin
has_attached_file :avatar
# Validate content type
validates_attachment_content_type :avatar, content_type: /\Aimage/
# Validate filename
validates_attachment_file_name :avatar, matches: [/png\Z/, /jpe?g\Z/]
# Explicitly do not validate
do_not_validate_attachment_file_type :avatar
=end
scope :actives, -> { where('status = 1') }
scope :inactives, -> { where('status = 0') }
end
Form:
<%= form_for(#course_clasification, html: { style: "flex-direction: column; width: 50%;", :multipart => true }) do |f| %>
<div class="actions">
<%= link_to '<i class="fa fa-chevron-circle-left" aria-hidden="true"></i> Regresar'.html_safe, course_clasifications_path, class: "btn-button button--indigo" %>
<%= f.submit((" " + t('action.save')).html_safe, :alt => "Guardar", :title => "Guardar", :class => "button__submit btn-button button--green", :style => "font-family: FontAwesome, verdana, sans-serif; float: right; margin-top: 0; margin-right: 7px;") %>
</div>
<% lang = current_user.localization.languaje %>
<% if #course_clasification.errors.any? %>
<div id="error_explanation">
<h2><%= t('activerecord.errors.template.header', count: #course_clasification.errors.size, model: t('activerecord.models.course_clasification')) %>:</h2>
<p>
<%= t('activerecord.errors.template.body') %>
</p>
<ul>
<% #course_clasification.errors.full_messages.each do |msg| %>
<li><%= msg %></li>
<% end %>
</ul>
</div>
<% end %>
<div class="field field-full" style="margin-top: 40px;">
<%= f.label t('str_name_areas_'+ lang) %><br />
<%= f.text_field :name %>
</div>
<div class="field field-full">
<%= f.label "Agregar imágen a player" %><br />
<%= f.file_field :picture %>
<%# if #course_clasification.avatar? %>
<%# image_tag #course_clasification.avatar.url(:thumb) %>
<%# end %>
</div>
<% end %>
Schema:
class CreateCourseClasification < ActiveRecord::Migration
def self.up
create_table :course_clasifications do |t|
t.string :name
t.text :description
t.boolean :status
t.string :picture
t.timestamps
end
end
end

Answer 1

One problem that I'm seeing is that you're not using Strong Parameters.
That means that
#course_clasification = CourseClasification.new(params[:course_clasification])
Will basically try to create an empty object since non of the params is whitelisted (whatever is not whitelisted is basically omitted by Rails), so the ActiveRecord object is invalid and the save fails.
Change it to something like
def course_classification_params
# make sure to list all the save params!
params.permit(:name, :description, :status, ...)
end
#course_clasification = CourseClasification.new(course_classification_params[:course_clasification])