使用Shrine on Rails 6创建的缩略图的URL出现问题

Question

我已经在这个问题上挣扎了几天，希望有人能帮上忙。我可能遗漏了一些明显的东西！

我正在使用Rails的神社插件上传PDF文件，并为第一页生成缩略图。PDF将加载到指定的存储空间中，缩略图也将在同一位置创建和排序。但是，我无法在视图中显示缩略图。

初始化器：

require "shrine"
require "shrine/storage/file_system"
#require "shrine/storage/memory"

Shrine.storages = {
    cache: Shrine::Storage::FileSystem.new("public", prefix: "uploads/cache"),
    store: Shrine::Storage::FileSystem.new("public", prefix: "uploads/store")
}

Shrine.plugin :activerecord    # loads Active Record integration
Shrine.plugin :cached_attachment_data # enables retaining cached file across form redisplays
Shrine.plugin :restore_cached_data  # extracts metadata for assigned cached files
Shrine.plugin :determine_mime_type
Shrine.plugin :validation_helpers
Shrine.plugin :validation
Shrine.plugin :derivatives
#Shrine.plugin :model, cache: false

上传者：

require "image_processing/mini_magick"

class FileUploader < Shrine
 include ImageProcessing::MiniMagick

 plugin :processing # allows hooking into promoting
 plugin :versions   # enable Shrine to handle a hash of files
 plugin :derivatives
 plugin :default_url
# plugin :delete_raw # delete processed files after uploading

 Attacher.validate do
  validate_max_size 5*1024*1024, message: "is too large (max is 5 MB)"
  validate_mime_type %w[application/pdf]
 end

 Attacher.derivatives do |original|
  magick = ImageProcessing::MiniMagick.source(original).loader(page:0).convert("jpeg")
  {
   thumb: magick.resize_to_limit!(200, 200) 
  }

 end

end

测试视图：

<p id="notice"><%= notice %></p>

<p>
  <strong>Number:</strong>
  <%= @issue.number %>
</p>

<p>
  <strong>Title:</strong>
  <%= @issue.title %>
</p>

<p>
  <strong>Data:</strong>
  <%= @issue.file_data %>
</p>

<p>
  <strong>Issue Preview</strong>
  <embed src="<%= @issue.file_url %>" width="80" height="160" />
</p>

<p>
  <strong>Issue Thumbnail:</strong>
  <%= image_tag @issue.file_url(:thumb) if @issue.file %>
</p>

<p>
  <strong>Issue:</strong>
  <%= image_tag @issue.file_url if @issue.file %>
</p>

<%= link_to 'Edit', edit_issue_path(@issue) %> |
<%= link_to 'Back', issues_path %>

此外，当我查看存储在file_data字段中的数据时，我没有看到为缩略图添加的信息。

文件数据：{"id":"fccd20a9323aa5b63fd912f4ca833ebb.pdf"，"storage":"store"，"metadata":{"filename":"pdf_sample.pdf"，"size":351987，“mime_type”：“应用程序/pdf”}}

Answer 1

您需要在将附件升级到永久存储时启用自动创建：

Shrine.plugin :derivatives, create_on_promote: true

或者在附件中手动处理衍生工具：

record.file_derivatives!