[python] Does Python have a toString() equivalent, and can I convert a db.Model element to String?

I'm writing a ToDo list app to help myself get started with Python. The app is running on GAE and I'm storing todo items in the Data Store. I want to display everyone's items to them, and them alone. The problem is that the app currently displays all items to all users, so I can see what you write, and you see what I write. I thought casting my todo.author object to a string and seeing if it matches the user's name would be a good start, but I can't figure out how to do that.

This is what I have in my main.py

... 
user = users.get_current_user()

if user:
    nickname = user.nickname()
    todos = Todo.all()
    template_values = {'nickname':nickname, 'todos':todos}
...

def post(self):

    todo = Todo()
    todo.author = users.get_current_user()
    todo.item = self.request.get("item")
    todo.completed = False

    todo.put()      
    self.redirect('/')

In my index.html I had this originally:

<input type="text" name="item" class="form-prop" placeholder="What needs to be done?" required/>
...
 <ul>
{% for todo in todos %}
  <input type="checkbox"> {{todo.item}} <hr />
{% endfor %}
</ul>

but I'd like to display items only to the user who created them. I thought of trying

{% for todo in todos %}
    {% ifequal todo.author nickname %}
  <input type="checkbox"> {{todo.item}} <hr />
    {% endifequal %}
{% endfor %}

to no avail. The list turns up blank. I assumed it is because todo.author is not a string. Can I read the value out as a string, or can I cast the object to String?

Thanks!

Edit: Here is my Todo class

class Todo(db.Model):
author = db.UserProperty()
item = db.StringProperty()
completed = db.BooleanProperty()
date = db.DateTimeProperty(auto_now_add=True)

Will changing my author to a StringProperty effect anything negatively? Maybe I can forgo casting altogether.

In function post():

todo.author = users.get_current_user()

So, to get str(todo.author), you need str(users.get_current_user()). What is returned by get_current_user() function ?

If it is an object, check does it contain a str()" function?

I think the error lies there.

str() is the equivalent.

However you should be filtering your query. At the moment your query is all() Todo's.

todos = Todo.all().filter('author = ', users.get_current_user().nickname()) 

or

todos = Todo.all().filter('author = ', users.get_current_user())

depending on what you are defining author as in the Todo model. A StringProperty or UserProperty.

Note nickname is a method. You are passing the method and not the result in template values.

In Python we can use the __str__() method.

We can override it in our class like this:

class User: 

    firstName = ''
    lastName = ''
    ...

    def __str__(self):
        return self.firstName + " " + self.lastName

and when running

print(user)

it will call the function __str__(self) and print the firstName and lastName

You should define the __unicode__ method on your model, and the template will call it automatically when you reference the instance.