Feature Flag Decision

A Feature Flag has two states: on and off. Different features are configured for each state. When a user accesses a feature with a Feature Flag applied, the SDK must be able to return either the on or off state. You can use the Hackle SDK to handle this state decision.

isFeatureOn

Pass the Feature Key to the isFeatureOn() method to receive the state result for the user. Then implement logic based on the state.

In the example code below, Feature Key 42 is passed and the User Identifier for the user whose state will be retrieved is "ae03e1adf".

Kotlin

import io.hackle.sdk.HackleClient

// Determines the user's state for the Feature Flag with Feature Key 42.
// Returns false (off state) if a decision cannot be made.
val isFeatureOn: Boolean = hackleClient.isFeatureOn(42, "ae03e1adf")

if (isFeatureOn) {
    // ON feature
} else {
    // OFF feature
}

Java

featureFlagDetail

The featureFlagDetail() method works the same as isFeatureOn() but additionally provides the reason for the state decision. This is useful for verifying that Override is working correctly or when the result proportion seems inconsistent with the configured Traffic Allocation.

You must pass the Feature Key as a parameter. In the example code below, Feature Key 42 is passed.

Kotlin

import io.hackle.sdk.HackleClient
import io.hackle.sdk.common.decision.FeatureFlagDecision

val decision: FeatureFlagDecision = hackleClient.featureFlagDetail(42, "ae03e1adf")

// Feature on/off status
val isFeatureOn: Boolean = decision.isOn()

// Decision reason
val reason: DecisionReason = decision.getReason()

Java

The decision reason is returned in a format such as SDK_NOT_READY. Refer to the table below for details.

Decision Reason	Description	Distribution Result
SDK_NOT_READY	The SDK is not ready to use. (e.g., initialization attempted with an invalid SDK Key)	Default state (off)
FEATURE_FLAG_NOT_FOUND	No Feature Flag was found for the provided Feature Key. The Feature Key may be incorrect, or the Feature Flag may be archived.	Default state (off)
FEATURE_FLAG_INACTIVE	The Feature Flag is in the off state.	Default state (off)
INDIVIDUAL_TARGET_MATCH	Matched by Individual Targeting.	State configured by Individual Targeting
TARGET_RULE_MATCH	Matched by User Targeting.	State configured by User Targeting
DEFAULT_RULE	Did not match either Individual Targeting or User Targeting.	State configured by default rule
EXCEPTION	An unknown error occurred.	Default state (off)

When using the Java/Kotlin SDK, duplicate exposure events for the same Feature Flag distribution result triggered consecutively by the same user within 1 minute are removed.

Events within 1 minute are counted as 1 occurrence.

Feature Flag Parameters

• You can also receive the parameter values for the state decision through the featureFlagDetail() method.

• The FeatureFlagDecision instance returned by featureFlagDetail() contains a ParameterConfig object with the full parameter configuration.

• Since parameter values configured in the Hackle Feature Flag screen are stored as key-value pairs, use the methods below according to the parameter type to retrieve the configured values.

• You can dynamically update values in the Feature Flag parameter configuration screen.

getString

• Returns parameter values configured as STRING or JSON type.

• Returns the value configured for False or True based on the state decision.

Kotlin

import io.hackle.sdk.HackleClient
import io.hackle.sdk.common.decision.FeatureFlagDecision
import io.hackle.sdk.common.ParameterConfig

val decision: FeatureFlagDecision = hackleClient.featureFlagDetail(42, "ae03e1adf")
val config: ParameterConfig = decision.config

val strValue: String = decision.getString("parameter_key_string_type", "defaultValue")
val strValueInConfig: String = config.getString("parameter_key_string_type", "defaultValue")

val jsonValue: String = decision.getString("parameter_key_json_type", "defaultValue")
val jsonValueInConfig: String = config.getString("parameter_key_json_type", "defaultValue")

Java

getInt

• Returns parameter values configured as Number type as an Int.

• Returns the value configured for False or True based on the state decision.

Kotlin

import io.hackle.sdk.HackleClient
import io.hackle.sdk.common.decision.FeatureFlagDecision
import io.hackle.sdk.common.ParameterConfig

val decision: FeatureFlagDecision = hackleClient.featureFlagDetail(42, "ae03e1adf")
val config: ParameterConfig = decision.config

val intValue: Int = decision.getInt("parameter_key_number_type", 0)
val intValueInConfig: Int = config.getInt("parameter_key_number_type", 0)

Java

getDouble

• Returns parameter values configured as Number type as a Double.

• Returns the value configured for False or True based on the state decision.

Kotlin

import io.hackle.sdk.HackleClient
import io.hackle.sdk.common.decision.FeatureFlagDecision
import io.hackle.sdk.common.ParameterConfig

val decision: FeatureFlagDecision = hackleClient.featureFlagDetail(42, "ae03e1adf")
val config: ParameterConfig = decision.config

val doubleValue: Double = decision.getDouble("parameter_key_number_type", 0.0)
val doubleValueInConfig: Double = config.getDouble("parameter_key_number_type", 0.0)

Java

getLong

• Returns parameter values configured as Number type as a Long.

• Returns the value configured for False or True based on the state decision.

Kotlin

import io.hackle.sdk.HackleClient
import io.hackle.sdk.common.decision.FeatureFlagDecision
import io.hackle.sdk.common.ParameterConfig

val decision: FeatureFlagDecision = hackleClient.featureFlagDetail(42, "ae03e1adf")
val config: ParameterConfig = decision.config

val longValue: Long = decision.getLong("parameter_key_number_type", 0L)
val longValueInConfig: Long = config.getLong("parameter_key_number_type", 0L)

Java

getBoolean

• Returns parameter values configured as Boolean type.

• Returns the value configured for False or True based on the state decision.

Kotlin

import io.hackle.sdk.HackleClient
import io.hackle.sdk.common.decision.FeatureFlagDecision
import io.hackle.sdk.common.ParameterConfig

val decision: FeatureFlagDecision = hackleClient.featureFlagDetail(42, "ae03e1adf")
val config: ParameterConfig = decision.config

val booleanValue: Boolean = decision.getBoolean("parameter_key_boolean_type", false)
val booleanValueInConfig: Boolean = config.getBoolean("parameter_key_boolean_type", false)

Java