ruby-on-rails – CarrierWave.无法使用STI保存文件

class Document < ActiveRecord::Base
  belongs_to :company
  validates :name,:presence => true
end

并且继承自Document的两个类：

执照：

class License < Document
  mount_uploader :file,DocumentUploader
end

和证书

class Certificate < Document
  mount_uploader :file,DocumentUploader
end

当我尝试对证书执行current_company.licenses.create(…)或相同的操作时,除了文件之外总是保存所有参数,总是为零

我也尝试在Document模型中挂载文件…请帮帮我.

这是日志：

Started POST "/companies/1/verified" for 127.0.0.1 at Mon Mar 19 09:33:41 +0200 2012
Processing by CompaniesController#verified as HTML
  Parameters: {"verified"=>{"certificate"=>{"name"=>"Certificate","file"=>"test.png"},"insured"=>"2000000","suppliers"=>"","license"=>{"name"=>"License","file"=>"test.png"}},"authenticity_token"=>"0hIn41Tjonm/AXZBKM1PE/tjQxJDLqZaojMTHDoZq2k=","id"=>"1","utf8"=>"?","commit"=>"Update verifications"}
  Company Load (0.7ms)  SELECT "companies".* FROM "companies" WHERE "companies"."id" = 1 LIMIT 1
   (0.1ms)  BEGIN
  SQL (0.8ms)  INSERT INTO "documents" ("company_id","created_at","file","name","type","updated_at","verified") VALUES ($1,$2,$3,$4,$5,$6,$7) RETURNING "id"  [["company_id",1],["created_at",Mon,19 Mar 2012 07:33:41 UTC +00:00],["file",nil],["name","License"],["type",["updated_at",["verified",false]]
   (0.6ms)  COMMIT
   (0.1ms)  BEGIN
  SQL (0.5ms)  INSERT INTO "documents" ("company_id","Certificate"],false]]
   (0.4ms)  COMMIT
Redirected to http://localhost:3000/company/profile
Completed 302 Found in 18ms (ActiveRecord: 3.3ms)

谢谢.