我正在处理多个文件上传器，我从上传器收到的params类似于：
"pdf_conta"=>{"0"=>#<ActionDispatch::Http::UploadedFile:0x007faed4374738 @tempfile=#<Tempfile:/tmp/RackMultipart20161010-6502-go0te.pdf>, @original_filename="AVENIDA.pdf", @content_type="binary/octet-stream", @headers="Content-Disposition: form-data; name=\"conta[pdf_conta][0]\"; filename=\"AVENIDA.pdf\"\r\nContent-Type: binary/octet-stream\r\n">,
"1"=>#<ActionDispatch::Http::UploadedFile:0x007faed4374440 @tempfile=#<Tempfile:/tmp/RackMultipart20161010-6502-e5t82z.pdf>, @original_filename="BANDEIRANTES.pdf", @content_type="binary/octet-stream", @headers="Content-Disposition: form-data; name=\"conta[pdf_conta][1]\"; filename=\"BANDEIRANTES.pdf\"\r\nContent-Type: binary/octet-stream\r\n">}}
并且我不能允许该参数，因为如果我将:pdf_conta => {}这样的内容放在我允许的参数上，它会给我Unpermitted parameters: 0, 1的错误。如何允许该哈希具有所需数量的索引？谢谢！