Solving IOError while generating a pdf using reportlab and generated qr code image

Question

I am trying to generate a qr code from text, and then insert into a reportlab pdf.

My code:

def qr_code_as_image(text):
    from io import BytesIO
    print("In show_qr")
    img = generate_qr_code(text)
    print(img, type(img))
    i = Image(img)
    print(i, type(i))
    return i

def add_patient_header_with_qr(self):
    line1 = ("Name", self.linkedcustomer.name,
             "Age", self.linkedcustomer.age())
    line2 = ("MRD No.", self.linkedcustomer.cstid,
             "Date", self.prescription_time)
    line3 = ("No.", "#", "Doctor", self.doc.name)
    datatb = [line1, line2, line3]
    patientdetailstable = Table(datatb)
    patientdetailstable.setStyle(self.patientdetails_style)
    col1 = patientdetailstable

    checkin_url = reverse('clinicemr', args=[self.checkin.checkinno])
    qr_image = qr_code_as_image(checkin_url)
    qr_image.hAlign = 'LEFT'

    col2 = Table([[qr_image]])

    tblrow1 = Table([[col1, col2]], colWidths=None)
    tblrow1.setStyle(self.table_left_top_align)
    self.elements.append(tblrow1)

def final_generate(self, footer_content, action=None):
        with NamedTemporaryFile(mode='w+b') as temp:
            from django.http import FileResponse, Http404
            from functools import partial

            # use the temp file
            cmd = "cat " + str(temp.name)
            print(os.system(cmd))
            print(footer_content, type(footer_content))
            doc = SimpleDocTemplate(
                temp.name,
                pagesize=A4,
                rightMargin=20,
                leftMargin=20,
                topMargin=20,
                bottomMargin=80,
                allowSplitting=1,
                title="Prescription",
                author="System.com")
            frame = Frame(doc.leftMargin, doc.bottomMargin, doc.width, doc.height,
                          id='normal')
            template = PageTemplate(
                id='test',
                frames=frame,
                onPage=partial(footer, content=footer_content)
            )

            doc.addPageTemplates([template])
            doc.build(self.elements,
                      onFirstPage=partial(footer, content=footer_content),
                      onLaterPages=partial(footer, content=footer_content)
                      )

            print(f'Generated {temp.name}')

I get the following output:

2020-11-29 13: 06: 33, 915 django.request ERROR    Internal Server Error: / clinic/presc/k-0NGpApcg
Traceback(most recent call last):
File "/home/joel/myappointments/venv/lib/python3.6/site-packages/reportlab/lib/utils.py", line 655, in open_for_read
    return open_for_read_by_name(name, mode)
File "/home/joel/myappointments/venv/lib/python3.6/site-packages/reportlab/lib/utils.py", line 599, in open_for_read_by_name
    return open(name, mode)
ValueError: embedded null byte

During handling of the above exception, another exception occurred:

Traceback(most recent call last):
File "/home/joel/myappointments/venv/lib/python3.6/site-packages/reportlab/lib/utils.py", line 658, in open_for_read
    return getBytesIO(datareader(name) if name[:5].lower() == 'data:' else urlopen(name).read())
File "/usr/lib/python3.6/urllib/request.py", line 223, in urlopen
    return opener.open(url, data, timeout)
File "/usr/lib/python3.6/urllib/request.py", line 517, in open
    req.timeout = timeout
AttributeError: 'bytes' object has no attribute 'timeout'

During handling of the above exception, another exception occurred:

Traceback(most recent call last):
File "/home/joel/myappointments/venv/lib/python3.6/site-packages/django/core/handlers/exception.py", line 34, in inner
    response = get_response(request)
File "/home/joel/myappointments/venv/lib/python3.6/site-packages/django/core/handlers/base.py", line 115, in _get_response
    response = self.process_exception_by_middleware(e, request)
File "/home/joel/myappointments/venv/lib/python3.6/site-packages/django/core/handlers/base.py", line 113, in _get_response
    response = wrapped_callback(request, *callback_args, **callback_kwargs)
File "/home/joel/myappointments/clinic/views.py", line 6879, in GoGetPrescription
    clinicobj = clinicobj,
File "/home/joel/myappointments/clinic/views.py", line 16222, in PDFPrescriptions
    return prescription.generate_pdf(action=action, rating=True)
File "/home/joel/myappointments/clinic/views.py", line 15415, in generate_pdf
    return self.final_generate(footer_content, action=action)
File "/home/joel/myappointments/clinic/views.py", line 15447, in final_generate
    onLaterPages = partial(footer, content=footer_content)
File "/home/joel/myappointments/venv/lib/python3.6/site-packages/reportlab/platypus/doctemplate.py", line 1291, in build
    BaseDocTemplate.build(self, flowables, canvasmaker=canvasmaker)
File "/home/joel/myappointments/venv/lib/python3.6/site-packages/reportlab/platypus/doctemplate.py", line 1056, in build
    self.handle_flowable(flowables)
File "/home/joel/myappointments/venv/lib/python3.6/site-packages/reportlab/platypus/doctemplate.py", line 912, in handle_flowable
    if frame.add(f, canv, trySplit=self.allowSplitting):
File "/home/joel/myappointments/venv/lib/python3.6/site-packages/reportlab/platypus/frames.py", line 174, in _add
    w, h = flowable.wrap(aW, h)
File "/home/joel/myappointments/venv/lib/python3.6/site-packages/reportlab/platypus/tables.py", line 1206, in wrap
    self._calc(availWidth, availHeight)
File "/home/joel/myappointments/venv/lib/python3.6/site-packages/reportlab/platypus/tables.py", line 641, in _calc
    W = self._calcPreliminaryWidths(availWidth)  # widths
File "/home/joel/myappointments/venv/lib/python3.6/site-packages/reportlab/platypus/tables.py", line 754, in _calcPreliminaryWidths
    new = elementWidth(value, style) or 0
File "/home/joel/myappointments/venv/lib/python3.6/site-packages/reportlab/platypus/tables.py", line 518, in _elementWidth
    w = v.minWidth()  # should be all flowables
File "/home/joel/myappointments/venv/lib/python3.6/site-packages/reportlab/platypus/tables.py", line 873, in minWidth
    style.leftPadding+style.rightPadding)
File "/home/joel/myappointments/venv/lib/python3.6/site-packages/reportlab/platypus/tables.py", line 512, in _elementWidth
    if hasattr(v, 'drawWidth') and isinstance(v.drawWidth, (int, float)): return v.drawWidth
File "/home/joel/myappointments/venv/lib/python3.6/site-packages/reportlab/platypus/flowables.py", line 494, in __getattr__
    self._setup_inner()
File "/home/joel/myappointments/venv/lib/python3.6/site-packages/reportlab/platypus/flowables.py", line 455, in _setup_inner
    img=self._img
File "/home/joel/myappointments/venv/lib/python3.6/site-packages/reportlab/platypus/flowables.py", line 488, in __getattr__
    self._img=ImageReader(self._file)
File "/home/joel/myappointments/venv/lib/python3.6/site-packages/reportlab/lib/utils.py", line 813, in __init__
    annotateException('\nfileName=%r identity=%s' %
                      (fileName, self.identity()))
File "/home/joel/myappointments/venv/lib/python3.6/site-packages/reportlab/lib/utils.py", line 1394, in annotateException
    rl_reraise(t, v, b)
File "/home/joel/myappointments/venv/lib/python3.6/site-packages/reportlab/lib/utils.py", line 147, in rl_reraise
    raise v
File "/home/joel/myappointments/venv/lib/python3.6/site-packages/reportlab/lib/utils.py", line 777, in __init__
    self.fp=open_for_read(fileName, 'b')
File "/home/joel/myappointments/venv/lib/python3.6/site-packages/reportlab/lib/utils.py", line 660, in open_for_read
    raise IOError('Cannot open resource "%s"' % name)
OSError: Cannot open resource "b'\x89PNG\r\n\x1a\n\x00\x00\x00\rIHDR\x00\x00\x00\xd2\x00\x00\x00\xd2\x01\x00\x00\x00\x00\x17\xe2\xa3\xef\x00\x00\x01$IDATx\x9c\xed\x98An\xc4 \x10\x04k\x16\xdf\xf1\x8f\xe0gyS~\x80\x9f\x92\x1f\xe0;\xab\xde\x03\xc6\xeb\x1c"\xe5d\xd0\xda\x1c\xd0 @\xcbRk4\x9e\xee\x01\xb6\xe5$\xa9 \xe5v\xc3\x83\xbf\xd7\xe7cA\x92\x94\xc1"N\x16k\x86\xa4\xd1x\x9e\x8bA\xc8@\xc8NJ\xbe e\'\xc0]</\x07\xccb\xdb\xfas\xe9\x8eM\xefP\xac\x13b\xed\xc6e0\xccKJ\x80\xd9\xecd\x11\x90T\xfap\x19\x06\xdb\x97\x13!;\xd5v\xd3\x87\xcbH\xd8\xa4=\x14\xeb\xd3\xc0\xb7\x9be$\x9e\x9d\xea\xa5V\x89/u\xab\xca\x94F\xe2yz^\x94\xbc\x04^\xda\x8ePe{,\x9e}\xeaE\xe9\xed\xe6\xe0\xae\x17\xa0\xa6#\xf9\xb2\x9b;\xe9\x1f\xdf}:\xc6A\x80v=\xbau\xba\xd5\xcb\xef_hk7#\xf1\xec\xee_\xf0\x92\x94\x9d.\xde_\xda<\xdd\xde\x19R\xb5\xbfW\xcf\xcb\x03V3\x8b\xb4\x911\xfc\x98\xd9\xd7\xe5\xfb\xcb\x11[f\'\x96\x19\x80\xa7\x8d\xcb\xf3\x0c\xec0O\x13\xbe\xa7b\xf8\x0c\x8b\xdd\xben\xef/\xc0\xf68\xb5E#\xf1\xec\xaaGU\xac\x9d\x08\xba\xba\xdf}\x01<\xf7\xbf\x8cN\xed-\x8a\x00\x00\x00\x00IEND\xaeB`\x82'"
fileName=b'\x89PNG\r\n\x1a\n\x00\x00\x00\rIHDR\x00\x00\x00\xd2\x00\x00\x00\xd2\x01\x00\x00\x00\x00\x17\xe2\xa3\xef\x00\x00\x01$IDATx\x9c\xed\x98An\xc4 \x10\x04k\x16\xdf\xf1\x8f\xe0gyS~\x80\x9f\x92\x1f\xe0;\xab\xde\x03\xc6\xeb\x1c"\xe5d\xd0\xda\x1c\xd0@\xcbRk4\x9e\xee\x01\xb6\xe5$\xa9 \xe5v\xc3\x83\xbf\xd7\xe7cA\x92\x94\xc1"N\x16k\x86\xa4\xd1x\x9e\x8bA\xc8@\xc8NJ\xbe e\'\xc0]</\x07\xccb\xdb\xfas\xe9\x8eM\xefP\xac\x13b\xed\xc6e0\xccKJ\x80\xd9\xecd\x11\x90T\xfap\x19\x06\xdb\x97\x13!;\xd5v\xd3\x87\xcbH\xd8\xa4=\x14\xeb\xd3\xc0\xb7\x9be$\x9e\x9d\xea\xa5V\x89/u\xab\xca\x94F\xe2yz^\x94\xbc\x04^\xda\x8ePe{,\x9e}\xeaE\xe9\xed\xe6\xe0\xae\x17\xa0\xa6#\xf9\xb2\x9b;\xe9\x1f\xdf}:\xc6A\x80v=\xbau\xba\xd5\xcb\xef_hk7#\xf1\xec\xee_\xf0\x92\x94\x9d.\xde_\xda<\xdd\xde\x19R\xb5\xbfW\xcf\xcb\x03V3\x8b\xb4\x911\xfc\x98\xd9\xd7\xe5\xfb\xcb\x11[f\'\x96\x19\x80\xa7\x8d\xcb\xf3\x0c\xec0O\x13\xbe\xa7b\xf8\x0c\x8b\xdd\xben\xef/\xc0\xf68\xb5E#\xf1\xec\xaaGU\xac\x9d\x08\xba\xba\xdf}\x01<\xf7\xbf\x8cN\xed-\x8a\x00\x00\x00\x00IEND\xaeB`\x82' identity=[ImageReader@0x7f1e0987ecf8 filename=b'\x89PNG\r\n\x1a\n\x00\x00\x00\rIHDR\x00\x00\x00\xd2\x00\x00\x00\xd2\x01\x00\x00\x00\x00\x17\xe2\xa3\xef\x00\x00\x01$IDATx\x9c\xed\x98An\xc4 \x10\x04k\x16\xdf\xf1\x8f\xe0gyS~\x80\x9f\x92\x1f\xe0;\xab\xde\x03\xc6\xeb\x1c"\xe5d\xd0\xda\x1c\xd0@\xcbRk4\x9e\xee\x01\xb6\xe5$\xa9 \xe5v\xc3\x83\xbf\xd7\xe7cA\x92\x94\xc1"N\x16k\x86\xa4\xd1x\x9e\x8bA\xc8@\xc8NJ\xbe e\'\xc0]</\x07\xccb\xdb\xfas\xe9\x8eM\xefP\xac\x13b\xed\xc6e0\xccKJ\x80\xd9\xecd\x11\x90T\xfap\x19\x06\xdb\x97\x13!;\xd5v\xd3\x87\xcbH\xd8\xa4=\x14\xeb\xd3\xc0\xb7\x9be$\x9e\x9d\xea\xa5V\x89/u\xab\xca\x94F\xe2yz^\x94\xbc\x04^\xda\x8ePe{,\x9e}\xeaE\xe9\xed\xe6\xe0\xae\x17\xa0\xa6#\xf9\xb2\x9b;\xe9\x1f\xdf}:\xc6A\x80v=\xbau\xba\xd5\xcb\xef_hk7#\xf1\xec\xee_\xf0\x92\x94\x9d.\xde_\xda<\xdd\xde\x19R\xb5\xbfW\xcf\xcb\x03V3\x8b\xb4\x911\xfc\x98\xd9\xd7\xe5\xfb\xcb\x11[f\'\x96\x19\x80\xa7\x8d\xcb\xf3\x0c\xec0O\x13\xbe\xa7b\xf8\x0c\x8b\xdd\xben\xef/\xc0\xf68\xb5E#\xf1\xec\xaaGU\xac\x9d\x08\xba\xba\xdf}\x01<\xf7\xbf\x8cN\xed-\x8a\x00\x00\x00\x00IEND\xaeB`\x82']

From the error, it appears that it is erroring out on getting the name of the image file. But there is no file. The image is being generated from BytesIO.

Answer 1

Your generate_qr_code function, which you did not show us, is NOT returning a BytesIO object. It's returning the raw bytes of the PNG image. When you print(img, type(img)) , it told you it was of type "bytes", right? That's a string of bytes, not a BytesIO object. If you wrap those bytes into a BytesIO object, then the reportlab Image constructor will be able to handle it.