在 Rails 中直接多部分上传到 Amazon S3
The S3 Multipart gem brings direct multipart uploading to S3 to Rails. Data is piped from the client straight to Amazon S3 and a server-side callback is run when the upload is complete.
Multipart uploading allows files to be split into many chunks and uploaded in parallel or succession (or both). This can result in dramatically increased upload speeds for the client and allows for the pausing and resuming of uploads. For a more complete overview of multipart uploading as it applies to S3, see the documentation here. Read more about the philosophy behind the gem on the Bitcast blog.
0.0.10.6 - See pull request 23 for detailed changes. Changes will be documented in README soon.
0.0.10.5 - See pull request 16 and 18 for detailed changes.
0.0.10.4 - Fixed a race condition that led to incorrect upload progress feedback.
0.0.10.3 - Fixed a bug that prevented 5-10mb files from being uploaded correctly.
0.0.10.2 - Modifications made to the database table used by the gem are now handled by migrations. If you are upgrading versions, run rails g s3_multipart:install_new_migrations followed by rake db:migrate. Fresh installs do not require subsequent migrations. The current version must now also be passed in to the gem's configuration function to alert you of breaking changes. This is done by setting a revision yml variable. See the section regarding the aws.yml file in the readme section below (just before "Getting Started").
0.0.9 - File type and size validations are now specified in the upload controller. Untested support for browsers that lack the FileBlob API
First, assuming that you already have an S3 bucket set up, you will need to paste the following into your CORS configuration file, located under the permissions tab in your S3 console.
*
PUT
GET
3000
ETag
Authorization
Content-Type
Content-Length
x-amz-date
origin
Access-Control-Expose-Headers
Next, install the gem, and add it to your gemfile.
gem install s3_multipart
Run the included generator to create the required migrations and configuration files. Make sure to migrate after performing this step.
rails g s3_multipart:install
If you are using sprockets, add the following to your application.js file. Make sure that the latest underscore and jQuery libraries have been required before this line. Lodash is not supported at this time.
//= require s3_multipart/lib
Also in your application.js file you will need to include the following:
…
This piece of code does some configuration and provides various callbacks that you can hook into. It will be discussed further at the end of the Getting Started guide below.
Finally, edit the aws.yml that was created in your config folder with the correct credentials for each environment. Set the revision number to the current version number. If breaking changes are made to the gem in a later version, then you will be notified when the two versions do not match in the log.
development:
access_key_id: ""
secret_access_key: ""
bucket: ""
revision: "#.#.#"
S3_Multipart comes with a generator to set up your upload controllers. Running
rails g s3_multipart:uploader video
creates a video upload controller (video_uploader.rb) which resides in "app/uploaders/multipart" and looks like this:
class VideoUploader
The multipart_uploader_form function is a view helper, and generates the necessary input elements. It takes in a string of html to be interpolated between the generated file input element and submit button. It also expects an upload controller (as a string or constant) to be passed in with the 'uploader' option. This links the upload form with the callbacks specified in the given controller.
The code above outputs this:
Select videos
Upload selected videos
Let's return to the javascript that you inserted into the application.js during setup. The S3MP constructor takes in a configuration object with a handful of required callback functions. It also takes in list of files (through the fileList property) that is an array of File objects. This could be retrieved by calling $("#uploader").get(0).files if the input element had an "uploader" id, or it could be manually constructed. See the internal tests for an example of this manual construction.
The S3MP constructor also returns an object that you can interact with. Although not demonstrated here, you can call cancel, pause, or resume on this object and pass in the zero-indexed key of the file in the fileList array you want to control.
First, create a file setup_credentials.rb in the spec folder.
# spec/setup_credentials.rb
S3Multipart.configure do |config|
config.bucket_name = ''
config.s3_access_key = ''
config.s3_secret_key = ''
config.revision = S3Multipart::Version
end
You can now run all of the RSpec and Capybara tests with rspec spec
Combustion is also used to simulate a rails application. Paste the following into a config.ru file in the base directory:
require 'rubygems'
require 'bundler'
Bundler.require :development
Combustion.initialize! :active_record, :action_controller,
:action_view, :sprockets
S3Multipart.configure do |config|
config.bucket_name = ''
config.s3_access_key = ''
config.s3_secret_key = ''
config.revision = S3Multipart::Version
end
run Combustion::Application
and boot up the app by running rackup. A fully functional uploader is now available if you visit http://localhost:9292
Jasmine tests are also available for the client-facing javascript library. After installing Grunt and PhantomJS, and running npm install once, you can run the tests headlessly by running grunt jasmine.
To re-build the javascript library, run grunt concat and to minify, grunt min.
S3_Multipart is very much a work in progress. If you squash a bug, make enhancements, or write more tests, please submit a pull request.
The library is working on the latest version of IE, Firefox, Safari, and Chrome. Tests for over 100 browsers are currently being conducted.
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