how to get the first element and the last element using django , Location.objects.all()

this is my code.

obj_list=Location.objects.all()
first_element=obj_list[0]
last_element=obj_list[-1]

then,

return render_to_response(template_name, {
        'first_element':first_element,
        'last_element':last_element,
    })

and in the template:

{{ first_element.terminal_id}} {{last_element.terminal_id}}

but it show nothing ,

what can i do ,

thanks