Django报错UnicodeEncodeError: 'ascii' codec can't encode characters 之解决方法
作者：我就是个世界
发表于：2008-04-03
原先用Python 2.4 + Django 0.95 写得程序，当我把环境升级到Python 2.5 + Django 0.97(geodjango)的时候，并且把两个表做了外键关链的情况下，发现后台添加数据，会出现错误，Python报错如下：
[code] [color=#FF0000]UnicodeEncodeError: 'ascii' codec can't encode characters in position 0-1: ordinal not in range(128)[/color] [/code]
找了好多地方，终于还是在[url=http://code.djangoproject.com/wiki/UnicodeBranch#PortingApplicationsTheQuickChecklist]官方[b]code.djangoproject.com[/b][/url]找到了答案，[separator]
[quote]Porting Applications (The Quick Checklist) ¶
One of the design goals of the Unicode branch is that very little significant changes to existing third-party code should be required. However, there are some things that developers should be aware of when writing applications designed to handle international input.
A detailed list of things you might wish to think about when writing your code is in the unicode.txt file in the documentation directory (also online). For the programmer on a deadline, here is the cheatsheet version (if you only use ASCII strings, none of these changes are necessary):
(Note (25 May 2007): Early adopters will have seen five steps in this list. The all-important step number 3 was initially omitted.)
1. [color=#FF0000]Change the __str__ methods on your models to be __unicode__ methods. Just change the name. Usually, nothing else will be needed. [/color]
2. Look for any str() calls in your code that operate on model fields. These should almost always be changed to smart_unicode() calls (which is imported from django.utils.encoding). In some cases, you may need to use force_unicode() (in the same module), but starting with a global change to smart_unicode() and then checking for problems is the "quick fix" way. (Details of the differences between the two functions are in unicode.txt.)
3. Change your string literals that include Python format characters to be unicode strings. For example, change this:
[code]formal_name = '%s %s %s' % (title, firstname, surname) # old version[/code]
to this:
[code]formal_name = u'%s %s %s' % (title, firstname, surname) # new version[/code]
This is useful for two reasons. Firstly, if the parameters contain non-ASCII characters, you won't have an exception raised. Secondly, if any of the parameters are objects, Python will automatically call their __unicode__ method and convert them to the right type. The "before" code would have resulted in the __str__ method being called instead. Of course, this step is only a good idea if you are interpolating unicode strings. If your parameters are bytestrings, they will not automatically be decoded to unicode strings before being interpolated (Python cannot read your mind). Use smart_unicode() for that purpose.
[b][color=#FF0000]×[/color][/b] Warning for Python 2.3: There is a bug in the way Python 2.3 does string interpolation for unicode strings that you should be aware of if your code has to work with that version of Python. In the second line of code, above, if any of the parameters are non-basestring objects, Python will call the __str__ method on the object, not the __unicode__ method! So, for Python 2.3-compatible code, you would need to write something like some_string = u'This is your object: %s' % unicode(some_object)
Note the explicit call to unicode() here to force the object to be the right type.
4. Use the unicode versions of the django.utils.translation.* functions. Replace gettext and ngettext with ugettext and ungettext respectively. There are also ugettext_lazy and ungettext_lazy functions if you use the lazy versions.
5. Make sure your database can store all the data you will send to it. Usually, this means ensuring it is using UTF-8 (or similar) encoding internally.
6. Use the FILE_CHARSET setting if your on-disk template files and initial SQL files are not UTF-8 encoded.
That is all. Enjoy!
[/quote]
Python中有两种字符串，分别是一般的字符串（每个字符用8 bits表示）和Unicode字符串（每个字符用一个或者多个字节表示），它们可以相互转换。从错误提示来看同由于Python遇到了编码问题，也就是说，后台输入的数据在默认情况下是[color=#0000FF]ascii[/color]编码的，那么在存入数据库的时候，Python便会报错，即使返回去看，数据库中已经插入了该条信息！
解决方法： 因为原先写的模型代码中的方法用提 [color=#0000FF]def __str__(self): [/color]这个是旧版本中用的方法，在Django 0.96以后的版本中，应该换成[color=#0000FF] def __unicode__(self):[/color]， 这样就解决了字符串传递时出错的问题，统一编码为Unicode字符串。
一下篇中详细介绍[b][color=#FF0000]Unicode 字符串[/color][/b]
[code] [color=#FF0000]UnicodeEncodeError: 'ascii' codec can't encode characters in position 0-1: ordinal not in range(128)[/color] [/code]
找了好多地方，终于还是在[url=http://code.djangoproject.com/wiki/UnicodeBranch#PortingApplicationsTheQuickChecklist]官方[b]code.djangoproject.com[/b][/url]找到了答案，[separator]
[quote]Porting Applications (The Quick Checklist) ¶
One of the design goals of the Unicode branch is that very little significant changes to existing third-party code should be required. However, there are some things that developers should be aware of when writing applications designed to handle international input.
A detailed list of things you might wish to think about when writing your code is in the unicode.txt file in the documentation directory (also online). For the programmer on a deadline, here is the cheatsheet version (if you only use ASCII strings, none of these changes are necessary):
(Note (25 May 2007): Early adopters will have seen five steps in this list. The all-important step number 3 was initially omitted.)
1. [color=#FF0000]Change the __str__ methods on your models to be __unicode__ methods. Just change the name. Usually, nothing else will be needed. [/color]
2. Look for any str() calls in your code that operate on model fields. These should almost always be changed to smart_unicode() calls (which is imported from django.utils.encoding). In some cases, you may need to use force_unicode() (in the same module), but starting with a global change to smart_unicode() and then checking for problems is the "quick fix" way. (Details of the differences between the two functions are in unicode.txt.)
3. Change your string literals that include Python format characters to be unicode strings. For example, change this:
[code]formal_name = '%s %s %s' % (title, firstname, surname) # old version[/code]
to this:
[code]formal_name = u'%s %s %s' % (title, firstname, surname) # new version[/code]
This is useful for two reasons. Firstly, if the parameters contain non-ASCII characters, you won't have an exception raised. Secondly, if any of the parameters are objects, Python will automatically call their __unicode__ method and convert them to the right type. The "before" code would have resulted in the __str__ method being called instead. Of course, this step is only a good idea if you are interpolating unicode strings. If your parameters are bytestrings, they will not automatically be decoded to unicode strings before being interpolated (Python cannot read your mind). Use smart_unicode() for that purpose.
[b][color=#FF0000]×[/color][/b] Warning for Python 2.3: There is a bug in the way Python 2.3 does string interpolation for unicode strings that you should be aware of if your code has to work with that version of Python. In the second line of code, above, if any of the parameters are non-basestring objects, Python will call the __str__ method on the object, not the __unicode__ method! So, for Python 2.3-compatible code, you would need to write something like some_string = u'This is your object: %s' % unicode(some_object)
Note the explicit call to unicode() here to force the object to be the right type.
4. Use the unicode versions of the django.utils.translation.* functions. Replace gettext and ngettext with ugettext and ungettext respectively. There are also ugettext_lazy and ungettext_lazy functions if you use the lazy versions.
5. Make sure your database can store all the data you will send to it. Usually, this means ensuring it is using UTF-8 (or similar) encoding internally.
6. Use the FILE_CHARSET setting if your on-disk template files and initial SQL files are not UTF-8 encoded.
That is all. Enjoy!
[/quote]
Python中有两种字符串，分别是一般的字符串（每个字符用8 bits表示）和Unicode字符串（每个字符用一个或者多个字节表示），它们可以相互转换。从错误提示来看同由于Python遇到了编码问题，也就是说，后台输入的数据在默认情况下是[color=#0000FF]ascii[/color]编码的，那么在存入数据库的时候，Python便会报错，即使返回去看，数据库中已经插入了该条信息！
解决方法： 因为原先写的模型代码中的方法用提 [color=#0000FF]def __str__(self): [/color]这个是旧版本中用的方法，在Django 0.96以后的版本中，应该换成[color=#0000FF] def __unicode__(self):[/color]， 这样就解决了字符串传递时出错的问题，统一编码为Unicode字符串。
一下篇中详细介绍[b][color=#FF0000]Unicode 字符串[/color][/b]
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