问题:

I need to upload and process a CSV file from a form in a Google App Engine application based on Webapp2 (Python) I understand I could use blobstore to temporary store the file but I am curious to know if there is a way to process the file without having to store it at all.

回答1:

The content of uploaded files is in self.request.POST in your handler, so you can get that content (assuming e.g the field for the uploaded file is named 'foo') with e.g

content = self.request.POST.multi['foo'].file.read()

So now you have the content as a string -- process it as you wish. This does of course assume the thing will fit in memory (no multi-megabyte uploads!-)...

回答2:

If you need to upload a file via webapp2 with an HTML form, the first thing you need to do is change HTML form enctype attribute to multipart/form-data, so the code snippet seems like:

<form action="/emails" class="form-horizontal" enctype="multipart/form-data" method="post">
    <input multiple id="file" name="attachments" type="file">
</form>

In python code, you can read the file directly via request.POST, here's a sample code snippet:

class UploadHandler(BaseHandler):
    def post(self):
        attachments = self.request.POST.getall('attachments')

        _attachments = [{'content': f.file.read(),
                         'filename': f.filename} for f in attachments]