我在Rails 3應用程序中使用來自Railscast#383(http://railscasts.com/episodes/383-uploading-to-amazon-s3)的Jquery多文件上傳器的修改版本,我需要調整它以檢查是否文件已經存在於S3上,如果存在,則跳過重新上傳。避免覆蓋S3文件使用Jquery-Fileupload
一些背景:我的用戶需要更新大塊的數據。例如,可以選擇500個4MB文件上傳。不可避免的是,他們的互聯網連接中斷,而不是期望用戶找出哪些文件上傳,哪些沒有上傳,我希望他們能夠選擇那些相同的500個文件,並且該應用足夠聰明,不會在一開始。
最好的解決方案是在S3 POST中包含一個選項,表示不覆蓋現有文件。接下來最好的方法是向S3發出GET以查看文件是否存在,如果存在則跳過它。
最好的是,我已經實現了一個解決方案,它非異步地向我的Rails應用程序發出GET請求(因爲我在每次上傳完成時創建了一個數據庫條目),但我似乎遇到了限制這些請求的問題,並且我的用戶說她的瀏覽器不斷崩潰(我猜想它一次可以完成500次)。
相關的application.js
//= require jquery
//= require jquery_ujs
//= require jquery.ui.all
//= require jquery-fileupload/basic
//= require jquery-fileupload/vendor/tmpl
我的形式:
<%= s3_uploader_form post: uploaded_photos_path, as: "uploaded_photo[image_url]", photo_shoot_id: @photo_shoot.id do %>
<%= file_field_tag :file, multiple: true %>
<%= button_tag 'Upload Photos', id: 'upload_photo_button', type: 'button' %>
<% end %>
我的javascript:
$(function() {
$('#s3_uploader').fileupload({
limitConcurrentUploads: 5,
add: function(e, data) {
var file, record_exists, photo_check_url;
file = data.files[0];
photo_check_url = "/my_route/has_photo_been_uploaded/" + encodeURIComponent(file.name)
// THIS IS MY NON-THROTTLING HACK THAT NEEDS REPLACEMENT/IMPROVEMENT
// THE CONTROLLER THAT HANDLES THE REQUEST JUST RENDERS AN INLINE STRING OF 'true' OR 'false'
$.ajax({
url: photo_check_url,
async: false,
success: function (result) {
record_exists = result;
}
});
if (record_exists == 'false') {
data.context = $(tmpl("template-upload", file));
$('#s3_uploader').append(data.context);
data.submit();
}
},
progress: function(e, data) { // irrelevant },
done: function(e, data) { // irrelevant. It posts the object to my database }
},
fail: function(e, data) { // irrelevant }
});
});
我的助手:
module S3UploaderHelper
def s3_uploader_form(options = {}, &block)
uploader = S3Uploader.new(options)
form_tag(uploader.url, uploader.form_options) do
uploader.fields.map do |name, value|
hidden_field_tag(name, value)
end.join.html_safe + capture(&block)
end
end
class S3Uploader
def initialize(options)
@options = options.reverse_merge(
id: "s3_uploader",
aws_access_key_id: ENV["S3_ACCESS_KEY"],
aws_secret_access_key: ENV["S3_SECRET_ACCESS_KEY"],
bucket: S3_BUCKET_NAME,
acl: "private",
expiration: 10.hours.from_now.utc,
max_file_size: 20.megabytes,
as: "file"
)
end
def form_options
{
id: @options[:id],
method: "post",
authenticity_token: false,
multipart: true,
data: {
post: @options[:post],
as: @options[:as]
}
}
end
def fields
{
:key => key,
:acl => @options[:acl],
:policy => policy,
:signature => signature,
"AWSAccessKeyId" => @options[:aws_access_key_id],
}
end
def key
@key ||= "uploaded_photos/${filename}"
end
def url
"https://#{@options[:bucket]}.s3.amazonaws.com/"
end
def policy
Base64.encode64(policy_data.to_json).gsub("\n", "")
end
def policy_data
{
expiration: @options[:expiration],
conditions: [
["starts-with", "$utf8", ""],
["starts-with", "$key", ""],
["content-length-range", 0, @options[:max_file_size]],
{bucket: @options[:bucket]},
{acl: @options[:acl]}
]
}
end
def signature
Base64.encode64(
OpenSSL::HMAC.digest(
OpenSSL::Digest::Digest.new('sha1'),
@options[:aws_secret_access_key], policy
)
).gsub("\n", "")
end
end
end
或者如果有一種方法可以遏制ADD事件的觸發,那也適用於我。 – LikeMaBell
也許我異步調用我的數據庫,然後添加一個監視'false'響應的鉤子,然後觸發提交(POST到S3)?有關代碼的外觀的任何提示? – LikeMaBell