CherryPy get uploaded file's temporary location

File Uppload in CherryPy:

    def upload(self, myFile):
        out = """File name: %s, Content-Type: %"""
        return out % (myFile.filename, myFile.content_type)
    upload.exposed = True

From docs:

When a client uploads a file to a CherryPy application, it’s placed on disk immediately. CherryPy will pass it to your exposed method as an argument (see “myFile” below); that arg will have a “file” attribute, which is a handle to the temporary uploaded file. If you wish to permanently save the file, you need to read() from myFile.file and write() somewhere else.

How can I get uploaded file's temporary location?

Solution

You can't get the name of the temporary file by using the default entity processor. But you can set you own custom one to ensue that a temporary file is always created (usually is not created for files <1000 bytes).

To have a name in the temporary file you need a NamedTemporaryFile which is created with the CustomPart class:

import tempfile
import cherrypy as cp

class App:

    @cp.expose
    def index(self):
        return """
        <html><body>
            <h2>Upload a file</h2>
            <form action="upload" method="post" enctype="multipart/form-data">
            filename: <input type="file" name="my_file" /><br />
            <input type="submit" />
            </form>
        </body></html>
        """

    @cp.expose
    def upload(self, my_file):
        return "The path is %s" % my_file.file.name


class CustomPart(cp._cpreqbody.Part):
    """
    Custom entity part that it will alway create a named
    temporary file for the entities.
    """
    maxrambytes = 0 # to ensure that it doesn't store it in memory

    def make_file(self):
        return tempfile.NamedTemporaryFile()


if __name__ == '__main__':
    cp.quickstart(App(), config={
        '/': {
            'request.body.part_class': CustomPart
        }
    })

You would not be able to see the file when the request is done because by default the NamedTemporaryFile class deletes the file as soon as it closed. In this case as soon as the request finish. You can add some sleep calls like this and validate what I have just said:

   @cp.expose
   def upload(self, my_file):
        import time
        cp.log.error("You have 30 seconds to open the temporary file %s" % my_file.file.name)
        time.sleep(30)
        return "The path is %s" % my_file.file.name

If you really want to keep the temporary file then you just have to set the delete parameter to False on the NamedTemporaryFile and end up with something like this:

 class CustomPart(cp._cpreqbody.Part):
        """
        Custom entity part that it will alway create a named
        temporary file for the entities.
        """
        maxrambytes = 0 # to ensure that it doesn't store it in memory

        def make_file(self):
            return tempfile.NamedTemporaryFile(delete=False)

You'll have to make sure that you delete those temporary files on your own.