Ask for consent - Matomo (Continuation Jayhaluska's work) (#245)

Co-authored-by: Julian Haluska <j.haluska@gmx.de>

CHANGELOG.rst

@@ -3,6 +3,7 @@
 * Fix GA gtag user_id setup and add support for custom dimensions (Erick Massip)
 * Change spelling of "JavaScript" across all files in docstrings and docs
   (Peter Bittner)
+* Ask site visitors for consent when using Matomo (Julian Haluska & Ronard Luna)
 
 Version 3.2.0
 -------------

analytical/templatetags/matomo.py

@@ -46,6 +46,30 @@ VARIABLE_CODE = (
 IDENTITY_CODE = '_paq.push(["setUserId", "%(userid)s"]);'
 DISABLE_COOKIES_CODE = "_paq.push(['disableCookies']);"
 
+GIVE_CONSENT_CLASS = 'matomo_give_consent'
+REMOVE_CONSENT_CLASS = 'matomo_remove_consent'
+ASK_FOR_CONSENT_CODE = """
+_paq.push(['requireConsent']);
+
+var elements = document.getElementsByClassName("{}");
+for (var i = 0; i < elements.length; i++) {{
+    elements[i].addEventListener("click",
+      function () {{
+        _paq.push(["forgetConsentGiven"]);
+      }}
+    );
+}}
+
+var elements = document.getElementsByClassName("{}");
+for (var i = 0; i < elements.length; i++) {{
+    elements[i].addEventListener("click",
+      function () {{
+        _paq.push(["rememberConsentGiven"]);
+      }}
+    );
+}}
+""".format(REMOVE_CONSENT_CLASS, GIVE_CONSENT_CLASS)
+
 DEFAULT_SCOPE = 'page'
 
 MatomoVar = namedtuple('MatomoVar', ('index', 'name', 'value', 'scope'))
@@ -103,6 +127,9 @@ class MatomoNode(Node):
         if getattr(settings, 'MATOMO_DISABLE_COOKIES', False):
             commands.append(DISABLE_COOKIES_CODE)
 
+        if getattr(settings, 'MATOMO_ASK_FOR_CONSENT', False):
+            commands.append(ASK_FOR_CONSENT_CODE)
+
         userid = get_identity(context, 'matomo')
         if userid is not None:
             variables_code = chain(

docs/services/matomo.rst

@@ -149,6 +149,28 @@ If you want to `disable cookies`_, set :data:`MATOMO_DISABLE_COOKIES` to
 
 .. _`disable cookies`: https://matomo.org/faq/general/faq_157/
 
+Ask for consent
+---------------
+
+If you do not want to track visitors without permission, you can `ask for consent`_ first.
+To enable this, set :data:`MATOMO_ASK_FOR_CONSENT` to :const:`True`. 
+By default, no consent for tracking is needed (i.e. :const:`False`).
+
+To give and remove consent in your page, create DOM elements with the following classes:
+
+`matomo_give_consent` - class name for element to click when visitors want to **give** consent
+`matomo_remove_consent` - class name for element to click when visitors want to **remove** consent
+
+Examples::
+
+    # button to allow tracking
+    <button class="matomo_give_consent">Track me!</button>
+
+    # button to remove tracking consent
+    <button class="matomo_remove_consent">Don't track me anymore!</button>
+
+.. _`asking for consent`: https://developer.matomo.org/guides/tracking-javascript-guide#asking-for-consent
+
 Internal IP addresses
 ---------------------
 

pyproject.toml

@@ -59,6 +59,8 @@ authors = [
     {name = "Tinnet Coronam", email = "tinnet@coronam.net"},
     {name = "Uros Trebec", email = "uros@trebec.org"},
     {name = "Walter Renner", email = "walter.renner@me.com"},
+    {name = "Julian Haluska", email = "mail@julianhaluska.de"},
+    {name = "Ronard Luna", email = "rlunag@proton.me"},
 ]
 maintainers = [
     {name = "Jazzband community", email = "jazzband-bot@users.noreply.github.com"},

tests/unit/test_tag_matomo.py

@@ -159,3 +159,8 @@ class MatomoTagTestCase(TagTestCase):
     def test_disable_cookies(self):
         r = MatomoNode().render(Context({}))
         assert "_paq.push(['disableCookies']);" in r
+
+    @override_settings(MATOMO_ASK_FOR_CONSENT=True)
+    def test_ask_for_consent(self):
+        r = MatomoNode().render(Context({}))
+        self.assertTrue("_paq.push(['requireConsent']);" in r, r)