Question

See my previous question. I updated the code as per Kevin P’s answer but now I am not able to sort with newest tag on top. My comments are below at query.order("date"). Do you know why date with a minus sign works but it does not work without minus sign?

my model is:

class Owner(db.Model):
    owner = db.UserProperty()
    owner_tag = db.StringProperty()
    tag_value = db.IntegerProperty()
    url = db.StringProperty()    

Handler that draws tag table:

class UserAdminPage(webapp.RequestHandler):
    def get(self):
        order_by = self.request.get("order")      
...

#-----------tags table-----------------#
            query = Owner.all()
            query.filter("owner =", user)
            if not order_by:
                query.order("owner_tag")
#-----------when both "date" has a minus sign the table is sorted correctly
#-----------when I remove the minus signs I get `PropertyError: Invalid property name 'date'`
            elif order_by == "-date":
                query.order("-date")
            w = query.fetch(500)

            user_tag_list = []
            for item in w:
                user_tag_list.append(item.owner_tag)

#            unique_tags = sorted(f1.f2(user_tag_list))                 
            unique_tags = f1.f2(user_tag_list) 

#-----------holding table start--------#
            self.response.out.write("""
            <table border="0" cellpadding="0" cellspacing="20" >
            <tr>
            <td>""")

#-----------tags table start--------#                                   
            self.response.out.write("""<table border="1">
            <tr>
            <th colspan="3">tags<br />
            <a href="/useradminpage?order=date"><span id=small>most recent</span></a></th>
            </tr>
            """)      

            for tag in unique_tags:

                self.response.out.write("""
                    <tr>
                    <td><a href="/tag?tag=%s">%s</a></td>
                    </tr>
                    """ %
                    (tag, tag)
                    )

            self.response.out.write("""</table>""")  

...

Answer 1

Right now you are relying on the fact that keys typically generate in sequence, which isn’t always the case. Add a date property to your model:

date= db.DateTimeProperty(auto_now_add=True)

Also fix your GET parameter so that it’s consistent. Here:

<a href="/useradminpage?order=xyz"><span id=small>most recent</span></a>

and here:

elif order_by == "xyz":
    query.order("date")