This section describe how to control what tags are embedded on your website when using Google Tag Manager for managing tags.

The key idea of the integration is that Didomi pushes GDPR consent information into Google Tag Manager as variables of the data layer. You should then configure GTM to only fire tags after consent has been collected for every vendor.

The integration relies on adding a trigger to all the tags from vendors that do not support the IAB framework to make them fire on a custom event from the data layer. The Didomi SDK will then fire an event with the list of vendors that the user has given consent to, which will ensure that Google Tag Manager only loads the tags matching the user consent.

For instance, if the user gives consent to the vendor didomi:google, the SDK will push the event didomi-consent-changed and the variable didomiVendorsConsent with the value didomi:google,. The tags setup in Google Tag Manager and with a trigger "didomiVendorsConsent" contains "didomi:google," will then be loaded by Google Tag Manager and other tags with triggers for a different vendor ID will not be loaded.

Configure the Didomi / GTM integration

Step 1 - Enable our GTM integration

Didomi Console

If you are configuring Didomi through the Console, enable the GTM integration in the Integrations tab of your consent notice.

Tag

If you are configuring Didomi through a didomiConfig tag, you need to update your tag configuration to enable our GTM integration in the SDK. The events and variables pushed by Didomi to the dataLayer will not be available until the integration is enabled.

Add the tagManager.provider key in your didomiConfig object:

<script type="text/javascript">
window.didomiConfig = {
  [...Your existing tag],
  
  tagManager: {
    provider: 'gtm'
  }
};
</script>

By default, Didomi uses window.dataLayer as the variable name for your GTM data layer. If you have renamed your data layer name (https://developers.google.com/tag-manager/devguide#renaming), you can instruct Didomi to use another variable name:

<script type="text/javascript">
window.didomiConfig = {
  [...Your existing tag],
  
  tagManager: {
    provider: 'gtm',
    dataLayerName: 'customDataLayer' // Custom data layer name (optional ; default to dataLayer)
  }
};
</script>

Step 2 - Create the variables in GTM

The Didomi SDK will automatically push variables and events to GTM that contain the user consent status. You can then use these custom variables and events to decide when to load a vendor tag on your website.

First, you need to create a data layer variable that maps to the didomiVendorsConsent variable that will be pushed by the SDK onto the data layer.

Go to the "Folders" section of your Google Tag Manager workspace:

Create a new folder named "Didomi" then create new user-defined variables, using the following configuration:

• Name: Didomi Vendors Consent

• Variable type: Data Layer Variable

• Data layer variable name: didomiVendorsConsent

Note: We recommend keeping Didomi's variables and triggers in a dedicated "Didomi" folder but you are free to structure resources differently.

Please read below for the list of all variables that are pushed to GTM by the Didomi SDK.

Step 3 - Create triggers

You need to create triggers that will be used to decide when to load each tag in Google Tag Manager.

For every vendor tag that you need to control, in the "Folders" section of the manager, add a new trigger to the Didomi folder, using the following configuration:

• Trigger name: "Vendor - IDXXX"

• Trigger type: Custom event

• Event name: one of the events pushed by Didomi (didomi-consent, didomi-ready or didomi-consent-changed)

• Fire this trigger when: Didomi Vendors Consent contains prefix:vendorID,

This trigger can now be used to define tags that fire only when the user has given consent for that vendor. Repeat this process for every vendor that you have.

How to find your vendor ID?

To find your vendor ID, go to the Vendors and Purposes section of your Didomi account and copy the SDK ID:

Step 4 - Classify your tags

You now need to classify your tags and define what user consent is required for firing each of them.

In the "Tags" section of the manager, edit each tag and add a trigger corresponding to the vendor that owns the tag.

Moving forward, every time you add a new tag that does not implement the IAB specification and that requires a GDPR consent, you must categorize it by adding the adequate trigger.

Variables

The Didomi SDK pushes variables to the GTM dataLayer to allow you to control when tags are loaded and to share the consent information with non-IAB vendors or IAB vendors with non-JavaScript pixels (usually image tags).

Here are the variables that the SDK pushes:

Vendors

These variables contain the consent status of the user for every vendor that you have defined in your configuration.

The consent status reported for vendors automatically includes the status for their required purposes. You usually do not have to create a trigger that uses both vendors AND purposes variables and a trigger on vendors is enough.

Example: didomi:google is only included in the list of vendors that the user has given consent to if the user has given consent to didomi:google and to every purpose required by that vendor.

Values

All variables have the same format: a comma-separated list of vendor IDs.

The list includes prefixes (iab: for IAB vendors, didomi: for Didomi vendors and c: for custom vendors) and is terminated by a final comma. Triggers on this variable should check if the variable contains prefix:ID, to guarantee that there is an exact and avoid a confusion between vendor prefix:1 and vendor prefix:10. Example: iab:1,iab:2,didomi:google,c:custom,

How to find your vendor ID?

To find your vendor ID, go to the Vendors and Purposes section of your Didomi account and copy the SDK ID:

Purposes

These variables contain the consent status of the user for every purpose that consent is collected for. You usually do not need to use these variables directly and want to use the Vendors variables instead.

GDPR & IAB

AB tests

We expose variables that the contain the status of the AB test running (if any). That allows you to track your AB tests results through your own analytics solution.

Events

The Didomi SDK pushes different events to the GTM dataLayer to allow you to use triggers to decide when to embed tags from your vendors. All the variables listed above are pushed with every event.

Here are the events that the SDK pushes:

Custom events and consent

If you have your own custom events that you use as triggers for tags and also want to add an additional condition on the consent status of the user, you need to make sure that your custom events only fire after the Didomi event that you are using (so that the Didomi variables have already been populated). You have two options to do so.

Wrap your custom events

In your JavaScript code that is pushing your custom events onto the data layer, wrap all your custom events to only fire them after the Didomi SDK has initialized and the didomi-ready event has been sent:

window.didomiOnReady = window.didomiOnReady || [];
window.didomiOnReady.push(function (Didomi) {
  // Fire your custom event(s)
  dataLayer.push({'event': 'custom_event'});
});

You can use as many didomiOnReady functions and put them anywhere in your code. Custom events that are not used as triggers for a tag that you want to condition on consent do not need to be wrapped.

Condition your custom events

The second option is to only fire your custom events when you have consent. In that case, you do not need to add a consent condition in GTM and the mere fact that the event gets fired implies that consent was given

It is not ideal because is pushes the consent condition into your JavaScript code but can be useful sometimes.

function fireCustomEvents(consentStatus) {  
  if (consentStatus === true) {
    // Fire your custom event(s) because the user has given consent
    dataLayer.push({'event': 'custom_event'});
  }
}
​
window.didomiOnReady = window.didomiOnReady || [];
window.didomiOnReady.push(function (Didomi) {
  // The SDK is done loading, check the consent status of the user
  const consentStatus = Didomi.getUserConsentStatusForVendor('vendor-id');
  
  if (consentStatus === true) {
    // The user has given consent for that vendor, fire the custom events
    fireCustomEvents(consentStatus);
  } else if(consentStatus === undefined) {
    // The consent status of the user is not known yet
    // Subscribe to the consent.changed event to get notified when it does
    Didomi.on('consent.changed', function () {
      // The consent status of the user has changed
      fireCustomEvents(Didomi.getUserConsentStatusForVendor('vendor-id'));
    });
  }
});