undefined method `upload' for nil:NilClass Did you mean? load

Question

Attempting to utilize ActiveStorage for a simple image upload form. It creates successfully, but upon submission it throws an error:

undefined method `upload' for nil:NilClass Did you mean? load

This is the block it wants me to look at:

    @comment = Comment.create! params.require(:comment).permit(:content)
    @comment.image.attach(params[:comment][:image])
    redirect_to comments_path 
  end

This is in the full controller:

class CommentsController < ApplicationController

  def new
    @comment = Comment.new
  end

  def create
    @comment = Comment.create! params.require(:comment).permit(:content)
    @comment.image.attach(params[:comment][:image])
    redirect_to comments_path 
  end

  def show
    @comment = Comment.find(params[:id])
  end
end

What should actually happen is it takes you to the page to view the upload. Here:

# new.html.erb

   <%= form_with model: @comment, local: true  do |form| %>
   <%= form.text_area :content %><br><br>
    <%= form.file_field :image %><br>
   <%= form.submit %>
  <% end %>

 # show.html.erb
   <%= image_tag @comment.image %>

Here's the comment.rb

class Comment < ApplicationRecord
  has_one_attached :image
end

Error in the log:

 app/controllers/comments_controller.rb:12:in `create'
 Started POST "/comments" for 127.0.0.1 at 2018-07-15 21:30:23 -0400
 Processing by CommentsController#create as HTML
  Parameters: {"utf8"=>"✓",             "authenticity_token"=>"Al2SdLm1r6RWXQ6SrKNdUTWscSJ4/ha3h8C3xl6GvUsDhBGHkiesvGgyjL         5E1B1eyRUrYyjovFTQaGKwAZ1wtw==", "comment"=>{"content"=>"fdfdfdsdf", "image"=>#       <ActionDispatch::Http::UploadedFile:0xb3d36d8 @tempfile=#<Tempfile:C:/Users/tduke     /AppData/Local/Temp/RackMultipart20180715-3328-10frg81.png>,       @original_filename="9c6f46a506b9ddcb318f3f9ba34bcb27.png",       @content_type="image/png", @headers="Content-Disposition: form-data;    name=\"comment[image]\"; filename=\"9c6f46a506b9ddcb318f3f9ba34bcb27.png     \"\r\nContent-Type: image/png\r\n">}, "commit"=>"Create Comment"}
 Completed 500 Internal Server Error in 468ms (ActiveRecord: 4.0ms)

 NoMethodError (undefined method `upload' for nil:NilClass

Did you mean? load):

Answer 1

I solved it by making sure that my Active Storage configuration in my environment file was set.

So, in development.rb, make sure the line

config.active_storage.service = :local

is present.

Answer 2

Try this:

@comment = Comment.new(params.require(:comment).permit(:content, :image))
@comment.save!
redirect_to comments_path 

ActiveRecord is smart enough to know that image is a file that is handled by ActiveStorage, so you don't need to manually attach it. I'm guessing that because the record is already persisted and the image isn't there it's throwing a fit.

Also you should move your strong params to a method.

def comment_params
  params.require(:comment).permit(:content, :image)
end 

And use like,

@comment = Comment.new(comment_params)
@comment.save!
redirect_to comments_path