UnicodeDecodeError: 'utf-8' codec can't decode byte 0x89 in position 0: invalid start byte

iMath redstone-cold at 163.com
Fri Dec 7 16:42:47 CET 2012


在 2012年12月6日星期四UTC+8下午7时07分35秒,Hans Mulder写道:
> On 6/12/12 11:07:51, iMath wrote:
> 
> > the following code originally from http://zetcode.com/databases/mysqlpythontutorial/
> 
> > within the "Writing images" part .
> 
> > 
> 
> > 
> 
> > import MySQLdb as mdb
> 
> > import sys
> 
> > 
> 
> > try:
> 
> >     fin = open("Chrome_Logo.svg.png",'rb')
> 
> >     img = fin.read()
> 
> >     fin.close()
> 
> > 
> 
> > except IOError as e:
> 
> > 
> 
> >     print ("Error %d: %s" % (e.args[0],e.args[1]))
> 
> >     sys.exit(1)
> 
> > 
> 
> > 
> 
> > try:
> 
> >     conn = mdb.connect(host='localhost',user='testuser',
> 
> >        passwd='test623', db='testdb')
> 
> >     cursor = conn.cursor()
> 
> >     cursor.execute("INSERT INTO Images SET Data='%s'" % \
> 
> >         mdb.escape_string(img))
> 
> 
> 
> You shouldn't call mdb.escape_string directly.  Instead, you
> 
> should put placeholders in your SQL statement and let MySQLdb
> 
> figure out how to properly escape whatever needs escaping.
> 
> 
> 
> Somewhat confusingly, placeholders are written as %s in MySQLdb.
> 
> They differ from strings in not being enclosed in quotes.
> 
> The other difference is that you'd provide two arguments to
> 
> cursor.execute; the second of these is a tuple; in this case
> 
> a tuple with only one element:
> 
> 
> 
>     cursor.execute("INSERT INTO Images SET Data=%s", (img,))
> 
> 
thanks,but it still doesn't work
> 
> >     conn.commit()
> 
> > 
> 
> >     cursor.close()
> 
> >     conn.close()
> 
> > 
> 
> > except mdb.Error as e:
> 
> > 
> 
> >     print ("Error %d: %s" % (e.args[0],e.args[1]))
> 
> >     sys.exit(1)
> 
> > 
> 
> > 
> 
> > I port it to python 3 ,and also change 
> 
> > fin = open("chrome.png") 
> 
> > to 
> 
> > fin = open("Chrome_Logo.png",'rb')
> 
> > but when I run it ,it gives the following error :
> 
> > 
> 
> > Traceback (most recent call last): 
> 
> >   File "E:\Python\py32\itest4.py", line 20, in <module>
> 
> >     mdb.escape_string(img))
> 
> > UnicodeDecodeError: 'utf-8' codec can't decode byte 0x89 in position 0: invalid start byte
> 
> > 
> 
> > so how to fix it ?
> 
> 
> 
> Python 3 distinguishes between binary data and Unicode text.
> 
> Trying to apply string functions to images or other binary
> 
> data won't work.
> 
> 
> 
> Maybe correcting this bytes/strings confusion and porting
> 
> to Python 3 in one go is too large a transformation.  In
> 
> that case, your best bet would be to go back to Python 2
> 
> and fix all the bytes/string confusion there.  When you've
> 
> got it working again, you may be ready to port to Python 3.
> 
> 
> 
> 
> 
> Hope this helps,
> 
> 
> 
> -- HansM




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