Feature Request: Global Event Parameters

[payam-zahedi]

Description

Is there a way to attach common parameters to every event sent through the trackers?

In many cases, it’s useful to include shared context with all events. For example, adding the current page/route would make it easier to understand where in the app an event was triggered.

Without this, the same parameter has to be manually added to every event, which is repetitive and error-prone.

Suggestion

It would be helpful to have a mechanism to add some event parameters to some events base on some conditions automatically. for example:

• You need to send page route information to the tracking system to know each event happend in which page.

This would make tracking more consistent and reduce boilerplate.

[alirezat66]

@payam-zahedi

The feature request is valid — FlexTrack does not currently support automatic attachment of common parameters to events.

Here's what exists vs. what's missing:

What exists:

TrackingContext stores session/user/device info, but it's not auto-attached to events
setUserProperties() sends context to individual trackers, but doesn't enrich event properties
What's missing:

An event enrichment / middleware layer that can inject shared parameters (e.g., current route) into every event before it hits the tracker

I am thinking to add a
Event transformers/middleware for package. Thanks to mentioned.

[alirezat66]

✅ Will support in v1.0.2 (upcoming)
Thanks for the suggestion — this is a great use case and we've added full support for it.

What's new: Event Transformers
You can now register event transformers — functions that automatically attach common parameters to every event before it reaches any tracker. No more repeating the same properties at every call site.

Quick example — attach current route to all events

// In main.dart, register once after FlexTrack.setup()
final routeObserver = FlexTrackRouteObserver();

FlexTrack.addTransformer((event) => EnrichedEvent(event, {
'current_route': routeObserver.currentRoute ?? 'unknown',
}));
That's it. Every event from that point on will carry current_route automatically.

Conditional enrichment
Only enrich events that match a condition:

FlexTrack.addTransformer(
conditionalTransformer(
(event) => event.category == EventCategory.business,
(event) => EnrichedEvent(event, {'experiment': 'variant_b'}),
),
);
Chaining
Multiple transformers are applied in registration order:

FlexTrack.addTransformer((e) => EnrichedEvent(e, {'route': routeObserver.currentRoute}));
FlexTrack.addTransformer((e) => EnrichedEvent(e, {'session_id': session.id}));
Removing a transformer

BaseEvent _myTransformer(BaseEvent e) => EnrichedEvent(e, {'env': 'prod'});

FlexTrack.addTransformer(_myTransformer);
// Later:
FlexTrack.removeTransformer(_myTransformer);
// Or remove everything:
FlexTrack.clearTransformers();
How it works
EnrichedEvent wraps your original event and merges extra properties — transformer properties win on key collision
All event metadata (category, containsPII, requiresConsent, etc.) is forwarded from the original unchanged
Transformers run at dispatch time, so dynamic values like the current route are always fresh
A failing transformer is silently skipped — it never breaks the pipeline
Works with both the global FlexTrack API and FlexTrackClient (dependency injection)
Full documentation in the README — Event transformers section.

[alirezat66]

@payam-zahedi if it is possible please check MR in https://github.com/alirezat66/flex_track/pull/9

[payam-zahedi]

Hey @alirezat66 I did a quick look.

Its LGTM