open pdf without text with python - django

Question

I want open a PDF for a Django views but my PDF has not a text and python returns me a blank PDF.
On each page, this is a scan of a page : link
from django.http import HttpResponse
def views_pdf(request, path):
with open(path) as pdf:
response = HttpResponse(pdf.read(),content_type='application/pdf')
response['Content-Disposition'] = 'inline;elec'
return response
Exception Type: UnicodeDecodeError
Exception Value: 'charmap' codec can't decode byte 0x9d in position 373: character maps to < undefined >
Unicode error hint
The string that could not be encoded/decoded was: � ��`����
How to say at Python that is not a text but a picture ?

Answer 1

By default, Python 3 opens files in text mode, that is, it tries to interpret the contents of a file as text. This is what causes the exception that you see.
Since a PDF file is (generally) a binary file, try opening the file in binary mode. In that case, read() will return a bytes object.
Here's an example (in IPython). First, opening as text:
In [1]: with open('2377_001.pdf') as pdf:
...: data = pdf.read()
...:
---------------------------------------------------------------------------
UnicodeDecodeError Traceback (most recent call last)
<ipython-input-1-d807b6ccea6e> in <module>()
1 with open('2377_001.pdf') as pdf:
----> 2 data = pdf.read()
3
/usr/local/lib/python3.6/codecs.py in decode(self, input, final)
319 # decode input (taking the buffer into account)
320 data = self.buffer + input
--> 321 (result, consumed) = self._buffer_decode(data, self.errors, final)
322 # keep undecoded input until the next call
323 self.buffer = data[consumed:]
UnicodeDecodeError: 'utf-8' codec can't decode byte 0xe2 in position 10: invalid continuation byte
Next, reading the same file in binary mode:
In [2]: with open('2377_001.pdf', 'rb') as pdf:
...: data = pdf.read()
...:
In [3]: type(data)
Out[3]: bytes
In [4]: len(data)
Out[4]: 45659
In [5]: data[:10]
Out[5]: b'%PDF-1.4\n%'
That solves the first part, how to read the data.
The second part is how to pass it to a HttpResponse. According to the Django documentation:
"Typical usage is to pass the contents of the page, as a string, to the HttpResponse constructor"
So passing bytes might or might not work (I don't have Django installed to test). The Django book says:
"content should be an iterator or a string."
I found the following gist to write binary data:
from django.http import HttpResponse
def django_file_download_view(request):
filepath = '/path/to/file.xlsx'
with open(filepath, 'rb') as fp: # Small fix to read as binary.
data = fp.read()
filename = 'some-filename.xlsx'
response = HttpResponse(mimetype="application/ms-excel")
response['Content-Disposition'] = 'attachment; filename=%s' % filename # force browser to download file
response.write(data)
return response

Answer 2

The problem is probably that the file you are trying to using isn't using the correct type of encoding. You can easily find the encoding of your pdf in most pdf viewers like adobe acrobat (in properties). Once you've found out what encoding it's using you can give it to Python like so:
Replace
with open(path) as pdf:
with :
with open(path, encoding="whatever encoding your pdf is in") as pdf:
Try Latin-1 encoding this often works