Handling cookie consent

pretix includes an optional feature to handle cookie consent explicitly to comply with EU regulations. If your plugin sets non-essential cookies or includes a third-party service that does so, you should integrate with this feature.

Server-side integration

First, you need to declare that you are using non-essential cookies by responding to the following signal:

pretix.presale.signals.register_cookie_providers = <pretix.base.signals.EventPluginSignal object>

Arguments: request

This signal is sent out to get all cookie providers that could set a cookie on this page, regardless of consent state. Receivers should return a list of pretix.presale.cookies.CookieProvider objects.

As with all event-plugin signals, the sender keyword argument will contain the event.

You are expected to return a list of CookieProvider objects instantiated from the following class:

class pretix.presale.cookies.CookieProvider

CookieProvider.identifier

A short and unique identifier used to distinguish this cookie provider form others (required).

CookieProvider.provider_name

A human-readable name of the entity of feature responsible for setting the cookie (required).

CookieProvider.usage_classes

A list of enum values from the pretix.presale.cookies.UsageClass enumeration class, such as UsageClass.ANALYTICS, UsageClass.MARKETING, or UsageClass.SOCIAL (required).

CookieProvider.privacy_url

A link to a privacy policy (optional).

Here is an example of such a receiver:

@receiver(register_cookie_providers)
def recv_cookie_providers(sender, request, **kwargs):
    return [
        CookieProvider(
            identifier='google_analytics',
            provider_name='Google Analytics',
            usage_classes=[UsageClass.ANALYTICS],
        )
    ]

JavaScript-side integration

The server-side integration only causes the cookie provider to show up in the cookie dialog. You still need to care about actually enforcing the consent state.

You can access the consent state through the window.pretix.cookie_consent variable. Whenever the value changes, a pretix:cookie-consent:change event is fired on the document object.

The variable will generally have one of the following states:

State	Interpretation
pretix === undefined || pretix.cookie_consent === undefined	Your JavaScript has loaded before the cookie consent script. Wait for the event to be fired, then try again, do not yet set a cookie.
pretix.cookie_consent === null	The cookie consent mechanism has not been enabled. This usually means that you can set cookies however you like.
pretix.cookie_consent[identifier] === undefined	The cookie consent mechanism is loaded, but has no data on your cookie yet, wait for the event to be fired, do not yet set a cookie.
pretix.cookie_consent[identifier] === true	The user has consented to your cookie.
pretix.cookie_consent[identifier] === false	The user has actively rejected your cookie.

If you are integrating e.g. a tracking provider with native cookie consent support such as Facebook’s Pixel, you can integrate it like this:

var consent = (window.pretix || {}).cookie_consent;
if (consent !== null && !(consent || {}).facebook) {
    fbq('consent', 'revoke');
}
fbq('init', ...);
document.addEventListener('pretix:cookie-consent:change', function (e) {
    fbq('consent', (e.detail || {}).facebook ? 'grant' : 'revoke');
})

If you have a JavaScript function that you only want to load if consent for a specific identifier is given, you can wrap it like this:

var consent_identifier = "youridentifier";
var consent = (window.pretix || {}).cookie_consent;
if (consent === null || (consent || {})[consent_identifier] === true) {
    // Cookie consent tool is either disabled or consent is given
    addScriptElement(src);
    return;
}

// Either cookie consent tool has not loaded yet or consent is not given
document.addEventListener('pretix:cookie-consent:change', function onChange(e) {
    var consent = e.detail || {};
    if (consent === null || consent[consent_identifier] === true) {
        addScriptElement(src);
        document.removeEventListener('pretix:cookie-consent:change', onChange);
    }
})