Change SQLa sample to be python 2 compatible

examples/sqla/simple.py

@@ -31,8 +31,8 @@ class User(db.Model):
     username = db.Column(db.String(80), unique=True)
     email = db.Column(db.String(120), unique=True)
 
-    # Required for administrative interface
-    def __str__(self):
+    # Required for administrative interface. For python 3 please use __str__ instead.
+    def __unicode__(self):
         return self.username
 
 
@@ -54,7 +54,7 @@ class Post(db.Model):
 
     tags = db.relationship('Tag', secondary=post_tags_table)
 
-    def __str__(self):
+    def __unicode__(self):
         return self.title
 
 
@@ -62,7 +62,7 @@ class Tag(db.Model):
     id = db.Column(db.Integer, primary_key=True)
     name = db.Column(db.Unicode(64))
 
-    def __str__(self):
+    def __unicode__(self):
         return self.name
 
 
@@ -75,7 +75,7 @@ class UserInfo(db.Model):
     user_id = db.Column(db.Integer(), db.ForeignKey(User.id))
     user = db.relationship(User, backref='info')
 
-    def __str__(self):
+    def __unicode__(self):
         return '%s - %s' % (self.key, self.value)
 
 
@@ -85,7 +85,7 @@ class Tree(db.Model):
     parent_id = db.Column(db.Integer, db.ForeignKey('tree.id'))
     parent = db.relationship('Tree', remote_side=[id], backref='children')
 
-    def __str__(self):
+    def __unicode__(self):
         return self.name