The `enabled_features` user property is prone to getting truncated in events

[andrewkolos]

Origin issue in flutter/flutter: flutter/flutter#147327

Currently, the Analytics constructor accepts an enabledFeatures argument¹. Whenever an event is sent, this string will get included in the event as a user property²³. Typically, enabledFeatures is a comma-delimited list of features that are enabled during a tool's invocation. For example, an event sent by the Flutter CLI tool (e.g. Event.flutterBuildInfo) could include an enabled_features user property of enable-native-assets,enable-swift-package-manager,explicit-package-dependencies.

The problem is that user property values are limited to 36 characters by GA4⁴. In our example, the value would get truncated to enable-native-assets,enable-swift-p. A few solutions were considered in flutter/flutter#147327 (comment). Namely, to completely avoid truncation issues (for all intents and purposes), I propose one event be submitted per enabled feature. Considering the prior example again, the Flutter tool would send the following events:

event name	event parameters
enabled_feature	name value label enable-native-assets value true
enabled_feature	name value label enable-swift-package-manager value true
enabled_feature	name value label explicit-package-dependencies value true

Event parameter values have a length limit of 100, which should be plenty.

During or after this change is made, the enabledFeatures parameter should be removed from the Analytics constructor, which would be a breaking change. Additionally, Analytics should support sending multiple events within a single HTTP request to avoid needing N HTTP roundtrips to send N of these events.

Footnotes

1. https://github.com/dart-lang/tools/blob/0b41bd203917157aa4f8f015c42c4f4c2e23c6b2/pkgs/unified_analytics/lib/src/analytics.dart#L49 ↩

2. https://github.com/dart-lang/tools/blob/0b41bd203917157aa4f8f015c42c4f4c2e23c6b2/pkgs/unified_analytics/lib/src/analytics.dart#L409 ↩

3. https://github.com/dart-lang/tools/blob/0b41bd203917157aa4f8f015c42c4f4c2e23c6b2/pkgs/unified_analytics/lib/src/utils.dart#L88 ↩

4. https://support.google.com/analytics/answer/9267744?hl=en ↩