I wrote a httpserver to serve html files for python2.7 and python3.5.
def do_GET(self):
...
#if resoure is api
data = json.dumps({'message':['thanks for your answer']})
#if resource is file name
with open(resource, 'rb') as f:
data = f.read()
self.send_response(response)
self.send_header('Access-Control-Allow-Origin', '*')
self.end_headers()
self.wfile.write(data) # this line raise TypeError: a bytes-like object is required, not 'str'
the code works in python2.7, but in python 3, it raised the above the error.
I could use bytearray(data, 'utf-8') to convert str to bytes, but the html is changed in web.
My question:
How to do to support python2 and python3 without use 2to3 tools and without change the file's encoding.
is there a better way to read a file and sent it content to client with the same way in python2 and python3 ?
thanks in advance.
You just have to open your file in binary mode, not in text mode:
with open(resource,"rb") as f:
data = f.read()
then, data is a bytes object in python 3, and a str in python 2, and it works for both versions.
As a positive side-effect, when this code hits a Windows box, it still works (else binary files like images are corrupt because of the endline termination conversion when opened in text mode).
Related
I'm trying to read all yaml files in a directory, but I am having trouble. First, because I am using Python 2.7 (and I cannot change to 3) and all of my files are utf-8 (and I also need them to keep this way).
import os
import yaml
import codecs
def yaml_reader(filepath):
with codecs.open(filepath, "r", encoding='utf-8') as file_descriptor:
data = yaml.load_all(file_descriptor)
return data
def yaml_dump(filepath, data):
with open(filepath, 'w') as file_descriptor:
yaml.dump(data, file_descriptor)
if __name__ == "__main__":
filepath = os.listdir(os.getcwd())
data = yaml_reader(filepath)
print data
When I run this code, python gives me the message:
TypeError: coercing to Unicode: need string or buffer, list found.
I want this program to show the content of the files. Can anyone help me?
I guess the issue is with filepath.
os.listdir(os.getcwd()) returns the list of all the files in the directory. so you are passing the list to codecs.open() instead of filename
There are multiple problems with your code, apart from that it is invalide Python, in the way you formatted this.
def yaml_reader(filepath):
with codecs.open(filepath, "r", encoding='utf-8') as file_descriptor:
data = yaml.load_all(file_descriptor)
return data
however it is not necessary to do the decoding, PyYAML is perfectly capable of processing UTF-8:
def yaml_reader(filepath):
with open(filepath, "rb") as file_descriptor:
data = yaml.load_all(file_descriptor)
return data
I hope you realise your trying to load multiple documents and always get a list as a result in data even if your file contains one document.
Then the line:
filepath = os.listdir(os.getcwd())
gives you a list of files, so you need to do:
filepath = os.listdir(os.getcwd())[0]
or decide in some other way, which of the files you want to open. If you want to combine all files (assuming they are YAML) in one big YAML file, you need to do:
if __name__ == "__main__":
data = []
for filepath in os.listdir(os.getcwd()):
data.extend(yaml_reader(filepath))
print data
And your dump routine would need to change to:
def yaml_dump(filepath, data):
with open(filepath, 'wb') as file_descriptor:
yaml.dump(data, file_descriptor, allow_unicode=True, encoding='utf-8')
However this all brings you to the biggest problem: that you are using PyYAML, that will mangle your YAML, dropping flow-style, comment, anchor names, special int/float, quotes around scalars etc. Apart from that PyYAML has not been updated to support YAML 1.2 documents (which has been the standard since 2009). I recommend you switch to using ruamel.yaml (disclaimer: I am the author of that package), which supports YAML 1.2 and leaves comments etc in place.
And even if you are bound to use Python 2, you should use the Python 3 like syntax e.g. for print that you can get with from __future__ imports.
So I recommend you do:
pip install pathlib2 ruamel.yaml
and then use:
from __future__ import absolute_import, unicode_literals, print_function
from pathlib import Path
from ruamel.yaml import YAML
if __name__ == "__main__":
data = []
yaml = YAML()
yaml.preserve_quotes = True
for filepath in Path('.').glob('*.yaml'):
data.extend(yaml.load_all(filepath))
print(data)
yaml.dump(data, Path('your_output.yaml'))
When I try to run:
import csv
with open('data.csv', 'rU') as csvfile:
reader = csv.DictReader(csvfile)
for row in reader:
pgd = Player.objects.get_or_create(
player_name=row['Player'],
team=row['Team'],
position=row['Position']
)
Most of my data gets created in the database, except for one particular row. When my script reaches the row, I receive the error:
ProgrammingError: You must not use 8-bit bytestrings unless you use a
text_factory that can interpret 8-bit bytestrings (like text_factory = str).
It is highly recommended that you instead just switch your application to Unicode strings.`
The particular row in the CSV that causes this error is:
>>> row
{'FR\xed\x8aD\xed\x8aRIC.ST-DENIS', 'BOS', 'G'}
I've looked at the other similar Stackoverflow threads with the same or similar issues, but most aren't specific to using Sqlite with Django. Any advice?
If it matters, I'm running the script by going into the Django shell by calling python manage.py shell, and copy-pasting it in, as opposed to just calling the script from the command line.
This is the stacktrace I get:
Traceback (most recent call last):
File "<console>", line 4, in <module>
File "/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/csv.py", line 108, in next
row = self.reader.next()
File "/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/codecs.py", line 302, in decode
(result, consumed) = self._buffer_decode(data, self.errors, final)
UnicodeDecodeError: 'utf8' codec can't decode byte 0xcc in position 1674: invalid continuation byte
EDIT: I decided to just manually import this entry into my database, rather than try to read it from my CSV, based on Alastair McCormack's feedback
Based on the output from your question, it looks like the person who made the CSV mojibaked it - it doesn't seem to represent FRÉDÉRIC.ST-DENIS. You can try using windows-1252 instead of utf-8 but I think you'll end up with FRíŠDíŠRIC.ST-DENIS in your database.
I suspect you're using Python 2 - open() returns str which are simply byte strings.
The error is telling you that you need to decode your text to Unicode string before use.
The simplest method is to decode each cell:
with open('data.csv', 'r') as csvfile: # 'U' means Universal line mode and is not necessary
reader = csv.DictReader(csvfile)
for row in reader:
pgd = Player.objects.get_or_create(
player_name=row['Player'].decode('utf-8),
team=row['Team'].decode('utf-8),
position=row['Position'].decode('utf-8)
)
That'll work but it's ugly add decodes everywhere and it won't work in Python 3. Python 3 improves things by opening files in text mode and returning Python 3 strings which are the equivalent of Unicode strings in Py2.
To get the same functionality in Python 2, use the io module. This gives you a open() method which has an encoding option. Annoyingly, the Python 2.x CSV module is broken with Unicode, so you need to install a backported version:
pip install backports.csv
To tidy your code and future proof it, do:
import io
from backports import csv
with io.open('data.csv', 'r', encoding='utf-8') as csvfile:
reader = csv.DictReader(csvfile)
for row in reader:
# now every row is automatically decoded from UTF-8
pgd = Player.objects.get_or_create(
player_name=row['Player'],
team=row['Team'],
position=row['Position']
)
Encode Player name in utf-8 using .encode('utf-8') in player name
import csv
with open('data.csv', 'rU') as csvfile:
reader = csv.DictReader(csvfile)
for row in reader:
pgd = Player.objects.get_or_create(
player_name=row['Player'].encode('utf-8'),
team=row['Team'],
position=row['Position']
)
In Django, decode with latin-1, csv.DictReader(io.StringIO(csv_file.read().decode('latin-1'))), it would devour all special characters and all comma exceptions you get in utf-8.
with gzip.open(sys.argv[5] + ".json.gz", mode="w", encoding="utf-8") as outfile:
It throws:
TypeError: open() got an unexpected keyword argument 'encoding'
But the docs says it exists
https://docs.python.org/3/library/gzip.html
Update
How can i encode and zip the file in Python 2.7?
I tried now this:
(but it don't work)
with gzip.open(sys.argv[5] + ".json.gz", mode="w") as outfile:
outfile = io.TextIOWrapper(outfile, encoding="utf-8")
json.dump(fdata, outfile, indent=2, ensure_ascii=False)
TypeError: must be unicode, not str
What can i do?
Those are the Python 3 docs. The Python 2 version of gzip does not allow encoding= as a keyword argument to gzip.open().
Seems the question has been answered sufficiently, but for your peace of mind: Alternatively to ensure that Python2 uses utf-8 as standard perhaps try the following, as it then becomes unnecessary to specify an encoding:
import sys
reload(sys)
sys.setdefaultencoding('UTF8')
hi im trying to watermark a pdf fileusing pypdf2 though i get this error i cant figure out what goes wrong.
i get the following error:
Traceback (most recent call last): File "test.py", line 13, in <module>
page.mergePage(watermark.getPage(0)) File "C:\Python27\site-packages\PyPDF2\pdf.py", line 1594, in mergePage
self._mergePage(page2) File "C:\Python27\site-packages\PyPDF2\pdf.py", line 1651, in _mergePage
page2Content, rename, self.pdf) File "C:Python27\site-packages\PyPDF2\pdf.py", line 1547, in
_contentStreamRename
op = operands[i] KeyError: 0
using python 2.7.6 with pypdf2 1.19 on windows 32bit.
hopefully someone can tell me what i do wrong.
my python file:
from PyPDF2 import PdfFileWriter, PdfFileReader
output = PdfFileWriter()
input = PdfFileReader(open("test.pdf", "rb"))
watermark = PdfFileReader(open("watermark.pdf", "rb"))
# print how many pages input1 has:
print("test.pdf has %d pages." % input.getNumPages())
print("watermark.pdf has %d pages." % watermark.getNumPages())
# add page 0 from input, but first add a watermark from another PDF:
page = input.getPage(0)
page.mergePage(watermark.getPage(0))
output.addPage(page)
# finally, write "output" to document-output.pdf
outputStream = file("outputs.pdf", "wb")
output.write(outputStream)
outputStream.close()
Try writing to a StringIO object instead of a disk file. So, replace this:
outputStream = file("outputs.pdf", "wb")
output.write(outputStream)
outputStream.close()
with this:
outputStream = StringIO.StringIO()
output.write(outputStream) #write merged output to the StringIO object
outputStream.close()
If above code works, then you might be having file writing permission issues. For reference, look at the PyPDF working example in my article.
I encountered this error when attempting to use PyPDF2 to merge in a page which had been generated by reportlab, which used an inline image canvas.drawInlineImage(...), which stores the image in the object stream of the PDF. Other PDFs that use a similar technique for images might be affected in the same way -- effectively, the content stream of the PDF has a data object thrown into it where PyPDF2 doesn't expect it.
If you're able to, a solution can be to re-generate the source pdf, but to not use inline content-stream-stored images -- e.g. generate with canvas.drawImage(...) in reportlab.
Here's an issue about this on PyPDF2.
I'm trying to upload and parse json files using django. Everything works great up until the moment I need to parse the json. Then I get this error:
No JSON object could be decoded: line 1 column 0 (char 0)
Here's my code. (I'm following the instructions here, and overwriting the handle_uploaded_file method.)
def handle_uploaded_file(f, collection):
# assert False, [f.name, f.size, f.read()[:50]]
t = f.read()
for j in serializers.deserialize("json", t):
add_item_to_database(j)
The weird thing is that when I uncomment the "assert" line, I get this:
[u'myfile.json', 59478, '']
So it looks like my file is getting uploaded with the right size (I've verified this on the server), but the read command seems to be failing entirely.
Any ideas?
I've seen this before. Your file has length, but reading it doesn't. I'm wondering if it's been read previously... try this:
f.seek(0)
f.read()