Consent

Consent comes down to three parts: the text the visitor agrees to, their decision, and what happens because of it. EventRail takes care of the decision and the session identifier. The rest is yours.

The consent text

Your banner tells the visitor what they agree to: what you do with their data, and what you don't. EventRail doesn't show or check this text. Whatever it promises, the rest of your setup has to keep. See Acting on the decision.

The decision

The decision is one of three values:

"unset" and "denied" are different: a visitor who hasn't been asked yet is not one who said no.

When the visitor answers, call producer.setConsent("accepted") or producer.setConsent("denied"). This stores the decision in the EventRailConsent cookie, for 180 days by default (set with consentMaxAge), and creates or removes the session identifier right away, as the storage policy allows. setConsent("unset") clears the decision. In React, producer.useConsent() returns the current decision, for example to show or hide your banner.

Every event carries the decision in effect when the Hub received it, in its consent field. See the EventRecord examples.

Events sent before the visitor answers carry consent: "unset", which can split one visit in two. Under optIn, the pages before the answer have no sessionId, so nothing links them to the session that follows. Under optOut, a visitor who refuses leaves a session made up of the pages they saw before answering. To keep events consistent, we suggest a banner that has to be answered before the page can be used, with the browser producer holding events until it is. See Blocking consent banner.

Acting on the decision

EventRail acts on the decision in one place: the session identifier. Everything else, including whether an event is stored at all, is up to you.

Storage policies

The storeSessionId option on the browser producer sets the policy. For each decision, it says whether the session identifier cookie is stored:

Events are collected under every policy. When no identifier is stored, their sessionId is null.

Storing events

Every event reaches your destinations, whatever the decision. Its consent field lets the systems downstream decide what to do with it.

If the law or your consent text requires you not to store events without consent, wrap a destination so it only writes records whose consent is "accepted":

import type { Destination } from "@eventrail/nextjs/core";

export function acceptedOnly(destination: Destination): Destination {
  return {
    name: destination.name,
    async write(record) {
      if (record.consent === "accepted") await destination.write(record);
    },
  };
}

Then pass your destination through it:

import "server-only";
import { createHub } from "@eventrail/nextjs/server";
import { createFileDestination } from "@eventrail/nextjs/destinations/file";
import { acceptedOnly } from "./accepted-only";

export const hub = createHub({
  destinations: [acceptedOnly(createFileDestination({ path: ".data/events.ndjson" }))],
});

A record with consent: "unset" or "denied" then never reaches the file. Other destinations in the list still receive it. See Your own destination for what a destination must do.