在app引擎中放置post函数时使用reportlab生成pdf的问题

Question

当用户提交表单时，我使用reportlab生成pdf。现在在测试时我将pdf生成代码放在get中 - 我正在按预期获得正确的pdf。但是当我在post函数中放置PDF生成代码时，问题出现了，没有生成pdf。我已经尝试过调试，遍历了pdf生成代码的所有部分。有什么问题？

感谢任何帮助。

以下是代码的一部分：

处理表单数据的PDF处理程序函数：

class PDFHandler(BlogHandler):


def get(self):

    self.render("create_offer_letter.html")




def post(self):   
    logging.info('Inside Post')


    candidate_name = self.request.get('candidate_name')
    candidate_email = self.request.get('candidate_email')
    candidate_address_street = self.request.get('candidate_address_street')
    candidate_address_city = self.request.get('candidate_address_city')
    candidate_address_state = self.request.get('candidate_address_state')
    candidate_address_country = self.request.get('candidate_address_country')
    candidate_address_pin = self.request.get('candidate_address_pin')
    candidate_phone = self.request.get('candidate_phone')
    course = self.request.get('course')
    institute = self.request.get('institute')
    admissionfee = int(self.request.get('admissionfee'))
    coursefee = int(self.request.get('coursefee'))

    feeterm = self.request.get('feeterm')
    confirmation_date = self.request.get('field4')
    candidate_address_part2 = candidate_address_city + candidate_address_state +candidate_address_pin
    candidate_address =  candidate_address_street + candidate_address_part2 + candidate_address_country
    address_part= [candidate_address_street, candidate_address_part2, candidate_address_country]



    generatePdf(self,candidate_name,candidate_email,candidate_phone,address_part,confirmation_date,coursefee,admissionfee,institute,course)   


    logging.info('End of Post') 

这是pdf生成函数，其中进行实际的pdf创建：

def generatePdf(self, candidate_name,candidate_email,candidate_phone,address_part,confirmation_date,coursefee,admissionfee,institute,course):

    logging.info('Inside PDF Creation')
    self.response.headers['Content-Type'] = 'application/pdf'
    self.response.headers['Content-Disposition'] = 'attachment; filename=my.pdf'

    c = canvas.Canvas(self.response.out, pagesize=A4)
    buff2 = StringIO.StringIO()

    # image_data is a raw string containing a JPEG
    # Draw it in the bottom left, 2 inches high and 2 inches wide

    doc = BaseDocTemplate(buff2,pagesize=A4,
                        rightMargin=12,leftMargin=12,
                        topMargin=12,bottomMargin=12)
    Story=[]
    magName = "Pythonista"
    issueNum = 12
    subPrice = "99.00"
    limitedDate = "03/05/2010"
    freeGift = "tin foil hat"
    #time.timezone('IST') 
    formatted_time = time.ctime()
    full_name = "Mike Driscoll"

    candidate_name="Siddhant" 
    #im = Image(buff, 8*inch, 11*inch)
    address_part =['hello', 'bye']
    #Story.append(im)

    styles=getSampleStyleSheet()
    styles.add(ParagraphStyle(name='Justify', alignment=TA_JUSTIFY))
    ptext = '<font size=12>%s</font>' % formatted_time

    Story.append(Paragraph(ptext, styles["Normal"]))
    Story.append(Spacer(1, 12))

    # Create return address
    #ptext = '<font size=12>%s</font>' % candidate_name
    #Story.append(Paragraph(ptext, styles["Normal"]))       
    #for part in address_part:
     #   ptext = '<font size=12>%s</font>' % part.strip()
      #  Story.append(Paragraph(ptext, styles["Normal"]))   

    #Story.append(Spacer(1, 12))
    #ptext = '<font size=12>Dear %s:</font>' % candidate_name.split()[0].strip()
    Story.append(Paragraph(ptext, styles["Normal"]))
    Story.append(Spacer(1, 12))

    ptext = '<font size=12>We would like to welcome you to our subscriber base for %s Magazine! \
            You will receive %s issues at the excellent introductory price of $%s. Please respond by\
            %s to start receiving your subscription and get the following free gift: %s.</font>' % (magName, 
                                                                                                    issueNum,
                                                                                                    subPrice,
                                                                                                    limitedDate,
                                                                                                    freeGift)
    Story.append(Paragraph(ptext, styles["Justify"]))
    Story.append(Spacer(1, 12))
    logging.info('Generating PDF')
    ptext = '<font size=12>Thank you very much and we look forward to serving you.</font>'
    Story.append(Paragraph(ptext, styles["Justify"]))
    Story.append(Spacer(1, 12))
    ptext = '<font size=12>Sincerely,</font>'
    Story.append(Paragraph(ptext, styles["Normal"]))
    Story.append(Spacer(1, 48))
    ptext = '<font size=12>Ima Sucker</font>'
    Story.append(Paragraph(ptext, styles["Normal"]))
    Story.append(Spacer(1, 12))
    frameT = Frame(2*inch, 0*inch, 6*inch, 10*inch, id='normal',showBoundary=0)
    doc.addPageTemplates([PageTemplate(id='first',frames=frameT,onPage=myFirstPage)])
    doc.build(Story)
    #c.drawString(100, 100, "Hello world")
    #text = c.beginText()
    #text.setTextOrigin(100, 500)
    #text.setFont("Times Roman", 14)
    #text.textLine("Hello world!")
    #text.textLine("Look ma, multiple lines!")
    #c.drawText(text)
    #response = HttpResponse(mimetype='application/pdf')
    #response['Content-Disposition'] = 'attachment; filename=output.pdf'  
    #f = Frame(inch, inch, 6*inch, 9*inch, showBoundary=1)
    #f.addFromList(Story,c)
    #c.showPage()
    #c.save()
    #self.response.clear()
    self.response.write(buff2.getvalue())
    buff2.close()
    logging.info('Exiting PDF Generation')