Gem Deprecated!
This gem is deprecated. Please use Echo Uploads instead.
Cached Uploads for Rails
This module enables you to upload files and persist them in a cache in the event that the form must be redisplayed (e.g. due to validation errors). This module also saves the files to their final location when the record is saved.
The controller is still responsible for the overall workflow. It should use the normal ActiveRecord API, with one addition: If the submission is invalid, the controller must call #write_temporary_files.
The controller (or cron task, or a worker process) should also call .clean_temporary_files from time to time. An easy option is to clean up any time an invalid submission is received.
Usage
In the model:
class UserAvatar
has_cached_upload(:file, {
folder: ->() { File.join Rails.root, 'uploads/screenshots' },
tmp_folder: ->() { File.join Rails.root, 'uploads/tmp_screenshots' },
filename: ->(a) { "#{a.id}.png" },
tmp_filename: ->(a) { "#{a.tmp_file_md5}#{a.file_ext}" }
})
# This could be a database column instead.
attr_accessor :file_ext
end
See the comments in cached_uploads.rb for more details.
In the form:
<% if f.object.tmp_file_md5.present? %>
<!-- These fields make the form "remember" the uploaded file
when validation fails. -->
<%= f.hidden_field :tmp_file_md5 %>
<%= f.hidden_field :file_ext %>
<% else %>
<%= f.label :file, 'File:' %>
<%= f.file_field :file %>
<% end %>
Testing
In the example above, your test cases would be writing to the same folder as your development server. That's probably not desirable. An improved solution would be something like this:
# In environments/development.rb and environments/production.rb
config.uploads_dir = File.join Rails.root, 'uploads'
# In environments/test.rb
config.uploads_dir = File.join Rails.root, 'test_uploads'
# In user_avatar.rb
has_cached_upload(:file, {
folder: ->() { File.join Rails.configuration.uploads_dir, 'screenshots' },
tmp_folder: ->() { File.join Rails.configuration.uploads_dir, 'tmp_screenshots' },
filename: ->(a) { "#{a.id}.png" },
tmp_filename: ->(a) { "#{a.tmp_file_md5}#{a.file_ext}" }
})