S3 预签名 URL：根据策略无效：策略条件失败 success_action_status

Question

我正在尝试通过我的服务器发布预签名 URL，然后在浏览器中通过 javascript 上传。当我省略 :success_action_status 字段时一切正常，但我想将其设置为 201 以在上传后取回 XML。

在服务器上：

s3_bucket = Aws::S3::Resource.new.bucket(UploadFile::DECK_BUCKET)
presigned_url = s3_bucket.presigned_post(
  :key => @upload_file.key,
  :content_length_range => 1..(10*1024),
  :success_action_status => '201',
  :signature_expiration => expire
)

data = { url: presigned_url.url, url_fields: presigned_url.fields }
render json: data, status: :ok

在客户端：

this.file.change(function() {
  var formData = new FormData();
  formData.append("key", that.fields.key);
  formData.append("X-Amz-Credential", that.fields['x-amz-credential']);
  formData.append("X-Amz-Algorithm", "AWS4-HMAC-SHA256");
  formData.append("X-Amz-Date", that.fields['x-amz-date']);
  formData.append("Policy", that.fields.policy);
  formData.append("X-Amz-Signature", that.fields['x-amz-signature']);
  formData.append("file", that.file[0].files[0]);
  formData.append("success_action_status", that.fields['success_action_status']);
  that.$http.post(that.url, formData).then(function(response) {
    console.log("yup")
    console.log(response)
  }, function(response) {
    console.log("nope")
    console.log(response)
  });

当我离开presigned_post 中的success_action_status 字段时，它再次起作用。但是当我没有得到时：

Invalid according to Policy: Policy Condition failed: ["eq", "$success_action_status", "201"]

谁知道怎么回事？？谢谢！

解决方案：

formData.append("file", that.file[0].files[0]); 必须是最后一个附加到表单的东西。

Answer 1

the documentation 中似乎没有具体说明为什么这不起作用。

更新

尝试将success_action_status 字段放在文件字段之前

this.file.change(function() {
  var formData = new FormData();
  formData.append("key", that.fields.key);
  formData.append("X-Amz-Credential", that.fields['x-amz-credential']);
  formData.append("X-Amz-Algorithm", "AWS4-HMAC-SHA256");
  formData.append("X-Amz-Date", that.fields['x-amz-date']);
  formData.append("Policy", that.fields.policy);
  formData.append("X-Amz-Signature", that.fields['x-amz-signature']);
  formData.append("success_action_status", that.fields['success_action_status']);
  formData.append("file", that.file[0].files[0]);
  that.$http.post(that.url, formData).then(function(response) {
    console.log("yup")
    console.log(response)
  }, function(response) {
    console.log("nope")
    console.log(response)
  });