Use isinstance to test for Unicode string

Question

How can I do something like:

>>> s = u'hello'
>>> isinstance(s,str)
False

But I would like isinstance to return True for this Unicode encoded string. Is there a Unicode string object type?

Asked By: A.D

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Source

Answer 1

Is there a Unicode string object type?

Yes, it is called unicode:

>>> s = u'hello'
>>> isinstance(s, unicode)
True
>>>

Note that in Python 3.x, this type was removed because all strings are now Unicode.

Answered By: user2555451

Answer 2

Test for str:

isinstance(unicode_or_bytestring, str)

or, if you must handle bytestrings, test for bytes separately:

isinstance(unicode_or_bytestring, bytes)

The two types are deliberately not exchangible; use explicit encoding (for str -> bytes) and decoding (bytes -> str) to convert between the types.

In Python 2, where the modern Python 3 str type is called unicode and str is the precursor of the Python 3 bytes type, you could use basestring to test for both:

isinstance(unicode_or_bytestring, basestring)

basestring is only available in Python 2, and is the abstract base type of both str and unicode.

If you wanted to test for just unicode, then do so explicitly:

isinstance(unicode_tring, unicode)

Answered By: Martijn Pieters

Answer 3

Is there a Unicode string object type?

Yes this works:

>>> s = u'hello'
>>> isinstance(s, unicode)
True
>>>

This is however only useful if you know that it is unicode.
Another solution is to use the six package, which saves you from python2.x and python3.x conversions and catches unicode and str

>>> unicode_s = u'hello'
>>> s = 'hello'
>>> isinstance(unicode_s, str)
False
>>> isinstance(unicode_s, unicode)
True
>>> isinstance(s, str)
True
>>> isinstance(unicode_s, str)
False
>>> isinstance(s, six.string_types)
True
>>> isinstance(unicode_s, six.string_types)
True

Answered By: eleijonmarck

Use isinstance to test for Unicode string

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