Can I access constants in settings.py from templates in Django?

If we were to compare context vs. template tags on a single variable, then knowing the more efficient option could be benificial. However, you might be better off to dip into the settings only from templates that need that variable. In that case it doesn't make sense to pass the variable into all templates. But if you are sending the variable into a common template such as the base.html template, Then it would not matter as the base.html template is rendered on every request, so you can use either methods.

If you decide to go with the template tags option, then use the following code as it allows you to pass a default value in, just in case the variable in-question was undefined.

Example: get_from_settings my_variable as my_context_value

Example: get_from_settings my_variable my_default as my_context_value

class SettingsAttrNode(Node):
    def __init__(self, variable, default, as_value):
        self.variable = getattr(settings, variable, default)
        self.cxtname = as_value

    def render(self, context):
        context[self.cxtname] = self.variable
        return ''


def get_from_setting(parser, token):
    as_value = variable = default = ''
    bits = token.contents.split()
    if len(bits) == 4 and bits[2] == 'as':
        variable = bits[1]
        as_value = bits[3]
    elif len(bits) == 5 and bits[3] == 'as':
        variable     = bits[1]
        default  = bits[2]
        as_value = bits[4]
    else:
        raise TemplateSyntaxError, "usage: get_from_settings variable default as value " \
                "OR: get_from_settings variable as value"

    return SettingsAttrNode(variable=variable, default=default, as_value=as_value)

get_from_setting = register.tag(get_from_setting)