ActiveStorage Image Upload Error with Rails 5.2: signed_id delegated to attachment, but attachment is nil

Question

I'm having an issue with image/pdf uploads with ActiveStorage. The images appear to be uploading without issue, but they are causing errors when I try to show them.

My blog model has_one_attached :image and has_one_attached :pdf. The uploads used to work (so I know I have ActiveStorage installed and my amazon s3 set up properly), but something has gone wrong.

The only complicated bit is I need it to work if it has a PDF or not (not all blogs will have a pdf...all should have an image).

My blog#create method is:

  def create
    @blog = Blog.new(blog_params)
    @blog.user_id = current_user.id
    if @blog.published
      @blog.published_on = DateTime.current
    end

    respond_to do |format|
      if @blog.save
        if @blog.image.attached?
          @blog.image.purge
        end
        @blog.image.attach(params[:image])
        if @blog.pdf.attached?
          @blog.pdf.purge
        end
        @blog.pdf.attach(params[:pdf])
        format.html { redirect_to @blog, notice: 'Blog was successfully created.' }
        format.json { render :show, status: :created, location: @blog }
      else
        format.html { render :new }
        format.json { render json: @blog.errors, status: :unprocessable_entity }
      end
    end
  end

My blog#update method is:

  def update
    if @blog.published
      @blog.published_on = DateTime.current
    end
    if @blog.image.attached?
      @blog.image.purge
    end
    @blog.image.attach(params[:image])
    if @blog.pdf.attached?
      @blog.pdf.purge
    end
    @blog.pdf.attach(params[:pdf])
    respond_to do |format|
      if @blog.update(blog_params)
        format.html { redirect_to @blog, notice: 'Blog was successfully updated.' }
        format.json { render :show, status: :ok, location: @blog }
      else
        format.html { render :edit }
        format.json { render json: @blog.errors, status: :unprocessable_entity }
      end
    end
  end

My form is simple:

<%= simple_form_for(@blog) do |f| %>
  <%= f.error_notification %>
  <%= f.error_notification message: f.object.errors[:base].to_sentence if f.object.errors[:base].present? %>

...
    <div class="form-group">
      <%= f.label "Blog Image" %><br />
      <%= f.file_field :image %>
    </div>
    <div class="form-group">
      <%= f.label "Linked PDF" %><br />
      <%= f.file_field :pdf %>
    </div>

...

  <div class="form-actions text-center">
    <%= f.button :submit, class: "btn-outline-primary" %>
  </div>
<% end %>

I'm trying to show the image in the blog like this:

<div class="frame" style="background-image: url(<%= rails_blob_url(@blog.image) %>)"></div>

And the PDF like this:

<h2 class="cta text-center"><%= link_to @blog.cta, rails_blob_url(@blog.pdf), target: "_blank" %></h2>

The error I'm getting is signed_id delegated to attachment, but attachment is nil on the place the image is called as a background image on the blog#show page. I get the same error on localhost and Heroku, if it helps.

Finally, I saw this error on this question and did try dropping and recreating my database, but to no avail.

Can anyone see what's going wrong here?

Galatians

How come you are purging the uploaded image and then reattaching it? – Millen

Can you show us the complete controller code? Specifically the strong parameters?Also, do you have ActiveRecord::Base.include_root_in_json set to true or false? – Menzies

Answer 1

I just ran into this error and really struggled to figure out what could have been happening. It first appeared when I submitted a form and did not include an attachment. Turns out I needed to check to see if something was really attached and deal with that possibility.

Perhaps try moving @blog.pdf.attach(params[:pdf]) to before the respond_to in blog#create

Then, when trying to show the image, maybe you could try something like this

<% if blog.pdf.attached? == false %>
  <p>No pdf attached</p>
<% elsif blog.pdf.previewable? %>
  <%= link_to(image_tag(blog.pdf.preview(resize: "50x50>")),  rails_blob_path(blog.pdf, disposition: "attachment"))
%>
<% elsif blog.pdf.variable? %>
  <%= link_to(image_tag(blog.pdf.variant(resize: "50x50")), rails_blob_path(blog.pdf, disposition: "attachment"))%>
<% else %>
  <%= link_to "Download file", rails_blob_path(@blog.pdf, disposition: "attachment") %>
<% end %>

Heroku has a good article on active storage here that may also help.

Disforest