Automatically Checking a Checkbox or Radio Button

The following:

<input type="checkbox" checked="${tg.checker(expression)}"/>

will create a checked checkbox if the expression is true. This works because tg.checker(expression) returns checked if the expression is true, otherwise None. If the return value is None, Kid will not render the attribute.

Dynamic checkboxes

To create a dynamic list of checkboxes (or radio buttons), with the appropriate ones pre-checked, you will put something like this in the controller:

# Create a class for your things.
# In reality, you would import it from your model file.

class Thing:
    def __init__(self, id):
        self.id = id
        self.label = 'Thing %d' % id

class Root(controllers.RootController):

    @turbogears.expose(...)
    def index(self):
        # Construct a list of things.
        # In reality, you would do a select on your model class.
        things = map(Thing, range(10))
        # Select some examples things.
        # In reality, these would be pulled from some other model object.
       things = map(Thing, range(10))
       return dict(things=things, selected_things=[3, 5, 8])

Then in the template:

<div py:for="thing in things" py:strip="True">
    <input type="checkbox" id="${thing.id}"
           name="selected_things" value="${thing.id}"
           checked="${tg.checker(thing.id in selected_things)}"/>
    <label py:content="thing.label" for="${thing.id}"/>
</div>

Using py:strip="True" means that the div will not be in the resulting HTML; we’re just using it as a wrapper, and the checkboxes will all appear in one line. Without the py:strip="True", the checkboxes will each appear in a separate div, i.e. in separate lines beneath each other.