`mobileAppVersion` not respected on boundary gating conditions

[maxmiranda]

Running version 3.9.10 of the growthbook_sdk_flutter.

We ran an experiment recently. Both the experiment & the feature flag had defined rules gating any user from viewing the experiment if they had an App Version < 1.18.1.

Experiment:

Feature Flag Rule:

The mobileAppVersion is set upon app initialization as follows:

final version = (await PackageInfo.fromPlatform()).version;
final growthBookBuilder = GBSDKBuilderApp(
  apiKey: growthbookKey(),
  hostURL: 'https://cdn.growthbook.io/',
  attributes: {
    if (user?.id != null) 'id': '${user!.id}',
    if (user?.email != null) 'email': user!.email,
    if (user?.createdAt != null) 'createdAt': user!.createdAt,
    'mobileAppVersion': version,
    'platform': platform,
  },
  growthBookTrackingCallBack: (trackingCallback) {
    ...
});
final growthBook = await growthBookBuilder.initialize();

Yet, somehow, these rules were not respected within Growthbook because we saw ultimately ~2000+ users still seeing the experiment.

Of those users, 27% were set to the non-Control Variant.

Being able to gate feature flags by version I believe is table stakes for an A/B Testing provider. Can someone please help us triage and figure out how this could've happened?

[vazarkevych]

Hi @maxmiranda . It looks like you're using the $gte operator to gate users based on app version (e.g., "mobileAppVersion": { "$gte": "1.18.1" }"). However, the $gte operator in growthbook_sdk_flutter performs numeric comparisons only using double.tryParse(...).
Since version strings like "1.18.1" cannot be parsed as valid numbers, the condition fails to evaluate correctly and instead returns the default result - true. This can unintentionally include all users in the experiment, regardless of their actual app version.
To properly compare semantic version strings (e.g., "1.18.1"), you should use the $vgte operator, which compares each version component correctly (major.minor.patch).
To fix this, go to the Advanced Settings of your targeting condition and use the following format:

{
  "mobileAppVersion": { "$vgte": "1.18.1" }
}

Please try this update and let us know if it resolves your issue.

[markrheeGI]

Thank you for the response @vazarkevych . Could you point me to the documentation outlining this nuance? If not the line of code where it does the parsing?

Thank you!

[vazarkevych]

Thank you for your question @maxmiranda.
Unfortunately, we don’t currently have documentation that outlines this specific nuance. However, you can see the relevant logic directly in the source code here.
In particular, this part of the code handles parsing and comparison for different types:
final targetPrimitiveValue = double.tryParse(conditionValue.toString());
final sourcePrimitiveValue = double.tryParse(attributeValue.toString());
final paddedVersionTarget = GBUtils.paddedVersionString(conditionValue.toString());
final paddedVersionSource = GBUtils.paddedVersionString(attributeValue?.toString() ?? '0.0');

bool evaluatedValue = false;
switch (operator) {
...
case "\$vgte":
return paddedVersionSource >= paddedVersionTarget;
...
case '\$gte':
evaluatedValue = (sourcePrimitiveValue ?? 0.0) >= (targetPrimitiveValue ?? 0);
break;
...
return evaluatedValue;
}
In this snippet, we can see that conditionValue is first attempted to be parsed both as a double (targetPrimitiveValue) and as a version string (paddedVersionTarget). Operators prefixed with $v such as $vgte rely on version comparison using padded strings. This is exactly what you were looking for.
In your specific case, since "1.18.0" could not be parsed as a double, double.tryParse returned null. As a result, the code likely fell back to comparing 0 >= 0, which returned true, possibly leading to unexpected evaluation.
Let me know if you need help digging deeper into this!