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fix(flags): fallback to API for multi-condition flags with static cohorts #86

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Merged
haacked merged 1 commit into from
Oct 23, 2025
Merged

fix(flags): fallback to API for multi-condition flags with static cohorts #86

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4 changes: 4 additions & 0 deletions lib/Client.php
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Original file line number Diff line number Diff line change
Expand Up @@ -256,6 +256,8 @@ public function getFeatureFlag(
$personProperties,
$groupProperties
);
} catch (RequiresServerEvaluationException $e) {
$result = null;
} catch (InconclusiveMatchException $e) {
$result = null;
} catch (Exception $e) {
Expand Down Expand Up @@ -387,6 +389,8 @@ public function getAllFlags(
$personProperties,
$groupProperties
);
} catch (RequiresServerEvaluationException $e) {
$fallbackToFlags = true;
} catch (InconclusiveMatchException $e) {
$fallbackToFlags = true;
} catch (Exception $e) {
Expand Down
14 changes: 13 additions & 1 deletion lib/FeatureFlag.php
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Original file line number Diff line number Diff line change
Expand Up @@ -103,7 +103,10 @@ public static function matchCohort($property, $propertyValues, $cohortProperties
{
$cohortId = strval($property["value"]);
if (!array_key_exists($cohortId, $cohortProperties)) {
throw new InconclusiveMatchException("can't match cohort without a given cohort property value");
throw new RequiresServerEvaluationException(
"cohort {$cohortId} not found in local cohorts - " .
"likely a static cohort that requires server evaluation"
);
}

$propertyGroup = $cohortProperties[$cohortId];
Expand Down Expand Up @@ -141,6 +144,9 @@ public static function matchPropertyGroup($propertyGroup, $propertyValues, $coho
return true;
}
}
} catch (RequiresServerEvaluationException $err) {
// Immediately propagate - this condition requires server-side data
throw $err;
} catch (InconclusiveMatchException $err) {
$errorMatchingLocally = true;
}
Expand Down Expand Up @@ -183,6 +189,9 @@ public static function matchPropertyGroup($propertyGroup, $propertyValues, $coho
return true;
}
}
} catch (RequiresServerEvaluationException $err) {
// Immediately propagate - this condition requires server-side data
throw $err;
} catch (InconclusiveMatchException $err) {
// If this is a flag dependency error, preserve the original message
if ($propType === 'flag') {
Expand Down Expand Up @@ -402,6 +411,9 @@ function ($conditionA, $conditionB) {
return FeatureFlag::getMatchingVariant($flag, $distinctId) ?? true;
}
}
} catch (RequiresServerEvaluationException $e) {
// Immediately propagate - this condition requires server-side data
throw $e;
} catch (InconclusiveMatchException $e) {
// If this is a flag dependency error, preserve the original message
if (
Expand Down
14 changes: 14 additions & 0 deletions lib/RequiresServerEvaluationException.php
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Original file line number Diff line number Diff line change
@@ -0,0 +1,14 @@
<?php

namespace PostHog;

use Exception;

class RequiresServerEvaluationException extends Exception
{
public function errorMessage()
{
$errorMsg = 'Error on line ' . $this->getLine() . ' in ' . $this->getFile() . ': <b> Requires Server Evaluation:' . $this->getMessage() . '</b>'; //phpcs:ignore
return $errorMsg;
}
}
91 changes: 91 additions & 0 deletions test/FeatureFlagLocalEvaluationTest.php
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Original file line number Diff line number Diff line change
Expand Up @@ -3840,4 +3840,95 @@ public function testFeatureFlagsWithFlagDependencies(): void
}
$this->assertTrue($threwException, "Expected InconclusiveMatchException was not thrown");
}

public function testFallsBackToAPIWhenFlagHasStaticCohort()
{
$this->http_client = new MockedHttpClient(
host: "app.posthog.com",
flagEndpointResponse: MockedResponses::LOCAL_EVALUATION_WITH_STATIC_COHORT,
flagsEndpointResponse: MockedResponses::FLAGS_WITH_STATIC_COHORT_RESPONSE
);

$this->client = new Client(
self::FAKE_API_KEY,
[
"debug" => true,
],
$this->http_client,
"test"
);

$result = $this->client->getFeatureFlag(
'multi-condition-flag',
'test-user',
[],
['$geoip_country_code' => 'DE']
);

// Should return 'set-1' from API, not 'set-8' from local evaluation
$this->assertEquals('set-1', $result);

$this->checkEmptyErrorLogs();
}

public function testFallsBackToAPIInGetAllFlagsWhenFlagHasStaticCohort()
{
$this->http_client = new MockedHttpClient(
host: "app.posthog.com",
flagEndpointResponse: MockedResponses::LOCAL_EVALUATION_WITH_STATIC_COHORT,
flagsEndpointResponse: MockedResponses::FLAGS_WITH_STATIC_COHORT_RESPONSE
);

$this->client = new Client(
self::FAKE_API_KEY,
[
"debug" => true,
],
$this->http_client,
"test"
);

$result = $this->client->getAllFlags(
'test-user',
[],
['$geoip_country_code' => 'DE']
);

// Should return flags from API
$this->assertEquals([
'multi-condition-flag' => 'set-1'
], $result);

$this->checkEmptyErrorLogs();
}

public function testFallsBackToAPIInGetFeatureFlagPayloadWhenFlagHasStaticCohort()
{
$this->http_client = new MockedHttpClient(
host: "app.posthog.com",
flagEndpointResponse: MockedResponses::LOCAL_EVALUATION_WITH_STATIC_COHORT_FOR_PAYLOAD,
flagsEndpointResponse: MockedResponses::FLAGS_WITH_STATIC_COHORT_PAYLOAD_RESPONSE
);

$this->client = new Client(
self::FAKE_API_KEY,
[
"debug" => true,
],
$this->http_client,
"test"
);

$result = $this->client->getFeatureFlagPayload(
'flag-with-payload',
'test-user'
);

// Should return payload from API, not local evaluation
$this->assertEquals([
'message' => 'from-api'
], $result);

$this->checkEmptyErrorLogs();
}
}
96 changes: 96 additions & 0 deletions test/assests/MockedResponses.php
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Original file line number Diff line number Diff line change
Expand Up @@ -1429,4 +1429,100 @@ class MockedResponses
],
]
];

public const LOCAL_EVALUATION_WITH_STATIC_COHORT = [
'flags' => [
[
'id' => 1,
'key' => 'multi-condition-flag',
'filters' => [
'groups' => [
[
'properties' => [
[
'key' => 'id',
'value' => 999,
'type' => 'cohort'
]
],
'rollout_percentage' => 100,
'variant' => 'set-1'
],
[
'properties' => [
[
'key' => '$geoip_country_code',
'operator' => 'exact',
'value' => ['DE'],
'type' => 'person'
]
],
'rollout_percentage' => 100,
'variant' => 'set-8'
]
],
'multivariate' => [
'variants' => [
['key' => 'set-1', 'rollout_percentage' => 50],
['key' => 'set-8', 'rollout_percentage' => 50]
]
],
'payloads' => [
'set-1' => '{"message": "local-payload-1"}',
'set-8' => '{"message": "local-payload-8"}'
]
],
'active' => true,
'is_simple_flag' => false
]
],
'cohorts' => []
];

public const FLAGS_WITH_STATIC_COHORT_RESPONSE = [
'featureFlags' => [
'multi-condition-flag' => 'set-1'
],
'featureFlagPayloads' => [
'multi-condition-flag' => '{"message": "from-api"}'
]
];

public const LOCAL_EVALUATION_WITH_STATIC_COHORT_FOR_PAYLOAD = [
'flags' => [
[
'id' => 2,
'key' => 'flag-with-payload',
'filters' => [
'groups' => [
[
'properties' => [
[
'key' => 'id',
'value' => 999,
'type' => 'cohort'
]
],
'rollout_percentage' => 100
]
],
'payloads' => [
'true' => '{"message": "local-payload"}'
]
],
'active' => true,
'is_simple_flag' => false
]
],
'cohorts' => []
];

public const FLAGS_WITH_STATIC_COHORT_PAYLOAD_RESPONSE = [
'featureFlags' => [
'flag-with-payload' => true
],
'featureFlagPayloads' => [
'flag-with-payload' => '{"message": "from-api"}'
]
];
}