Fixed #5134 -- Return empty strings as Unicode in psycopg1 backend.

git-svn-id: http://code.djangoproject.com/svn/django/trunk@5834 bcc190cf-cafb-0310-a4f2-bffc1f526a37

django/db/backends/postgresql/base.py

@@ -278,7 +278,7 @@ def typecast_string(s):
     """
     Cast all returned strings to unicode strings.
     """
-    if not s:
+    if not s and not isinstance(s, str):
         return s
     return smart_unicode(s)
 

tests/regressiontests/model_regress/models.py

@@ -10,6 +10,7 @@ class Article(models.Model):
     headline = models.CharField(max_length=100, default='Default headline')
     pub_date = models.DateTimeField()
     status = models.IntegerField(blank=True, null=True, choices=CHOICES)
+    misc_data = models.CharField(max_length=100, blank=True)
 
     class Meta:
         ordering = ('pub_date','headline')
@@ -30,5 +31,10 @@ An empty choice field should return None for the display name.
 >>> a.save()
 >>> a.get_status_display() is None
 True
+
+Empty strings should be returned as Unicode
+>>> a2 = Article.objects.get(pk=a.id)
+>>> a2.misc_data
+u''
 """
 }