xralf xralf - 1 year ago 134
Python Question

Usage of unicode() and encode() functions in Python

I have a problem with encoding of the path variable and inserting it to the SQLite database. I tried to solve it with encode("utf-8") function which didn't help. Then I used unicode() function which gives me type unicode.

print type(path) # <type 'unicode'>
path = path.replace("one", "two") # <type 'str'>
path = path.encode("utf-8") # <type 'str'> strange
path = unicode(path) # <type 'unicode'>

Finally I gained unicode type, but I still have the same error which was present when the type of the path variable was str

sqlite3.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.

Could you help me solve this error and explain the correct usage of
functions? I'm often fighting with it.


This execute() statement raised the error:

cur.execute("update docs set path = :fullFilePath where path = :path", locals())

I forgot to change the encoding of fullFilePath variable which suffers with the same problem, but I'm quite confused now. Should I use only unicode() or encode("utf-8") or both?

I can't use

fullFilePath = unicode(fullFilePath.encode("utf-8"))

because it raises this error:

UnicodeDecodeError: 'ascii' codec can't decode byte 0xc5 in position
32: ordinal not in range(128)

Python version is 2.7.2

Answer Source

You are using encode("utf-8") incorrectly. Python byte strings (str type) have an encoding, Unicode does not. You can convert a Unicode string to a Python byte string using uni.encode(encoding), and you can convert a byte string to a Unicode string using s.decode(encoding) (or equivalently, unicode(s, encoding)).

If fullFilePath and path are currently a str type, you should figure out how they are encoded. For example, if the current encoding is utf-8, you would use:

path = path.decode('utf-8')
fullFilePath = fullFilePath.decode('utf-8')

If this doesn't fix it, the actual issue may be that you are not using a Unicode string in your execute() call, try changing it to the following:

cur.execute(u"update docs set path = :fullFilePath where path = :path", locals())
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