message.py 文件源码

def attach(self, filename=None, content=None, mimetype=None):
        """
        Attaches a file with the given filename and content. The filename can
        be omitted and the mimetype is guessed, if not provided.

        If the first parameter is a MIMEBase subclass it is inserted directly
        into the resulting message attachments.

        For a text/* mimetype (guessed or specified), when a bytes object is
        specified as content, it will be decoded as UTF-8. If that fails,
        the mimetype will be set to DEFAULT_ATTACHMENT_MIME_TYPE and the
        content is not decoded.
        """
        if isinstance(filename, MIMEBase):
            assert content is None
            assert mimetype is None
            self.attachments.append(filename)
        else:
            assert content is not None

            if not mimetype:
                mimetype, _ = mimetypes.guess_type(filename)
                if not mimetype:
                    mimetype = DEFAULT_ATTACHMENT_MIME_TYPE
            basetype, subtype = mimetype.split('/', 1)

            if basetype == 'text':
                if isinstance(content, six.binary_type):
                    try:
                        content = content.decode('utf-8')
                    except UnicodeDecodeError:
                        # If mimetype suggests the file is text but it's actually
                        # binary, read() will raise a UnicodeDecodeError on Python 3.
                        mimetype = DEFAULT_ATTACHMENT_MIME_TYPE

            self.attachments.append((filename, content, mimetype))