Variation Distribution

When running an A/B Test, you need to assign users to Variations and implement logic for each Variation. You can use the Hackle SDK to handle this user distribution.

variation

Pass the Experiment Key to the variation() method to assign users to a Variation and receive the result.

Parameter	Type	Required	Constraints
Experiment Key (key)	int	Required	-

Example

In the example code below, Experiment Key 42 is passed, and there are two Variations: A and B.

import "package:hackle/hackle.dart";

// Determines which Variation to show to the user in the A/B Test with Experiment Key 42.
// Returns Variation A if a decision cannot be made.
Variation variation = await HackleApp.variation(42);

// Logic for the assigned Variation
if (variation == Variation.A) {
  // Group A logic
} else {
  // Group B logic
}

variationDetail

The variationDetail() method works the same as variation() but additionally provides the reason for the distribution decision. This method is useful for verifying that distribution is working correctly.

Parameter	Type	Required	Constraints
Experiment Key (key)	int	Required	-

Example

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

import "package:hackle/hackle.dart";

// Variation distribution decision detail
Decision decision = await HackleApp.variationDetail(42);

// Assigned Variation
Variation variation = decision.variation;

// Decision reason
DecisionReason reason = decision.reason;

Decision Reason

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

Distribution Reason	Description	Distribution Result
SDK_NOT_READY	The SDK is not ready to use. (e.g., initialization attempted with an invalid SDK Key)	A (Control Group)
EXPERIMENT_NOT_FOUND	No A/B Test was found for the provided Experiment Key. The Experiment Key may be incorrect, or the experiment may be archived.	A (Control Group)
NOT_IN_MUTUAL_EXCLUSION_EXPERIMENT	The experiment is included in Mutually Exclusive Settings, but the user was not assigned to that Mutually Exclusive Group.	A (Control Group)
EXPERIMENT_DRAFT	The A/B Test is in draft state.	A (Control Group)
EXPERIMENT_PAUSED	The A/B Test is paused.	A (Control Group)
EXPERIMENT_COMPLETED	The A/B Test has ended.	Winning Variation selected at completion
OVERRIDDEN	The user was assigned to a specific group by Override.	Override-assigned group
NOT_IN_EXPERIMENT_TARGET	The user is not an A/B Test target.	A (Control Group)
TRAFFIC_NOT_ALLOCATED	The A/B Test is running, but the user was not allocated to the test.	A (Control Group)
TRAFFIC_ALLOCATED	The user has been allocated to the A/B Test.	Allocated group
VARIATION_DROPPED	The originally allocated group has been removed from the test.	A (Control Group)
INVALID_INPUT	The input value is invalid.	A (Control Group)
EXCEPTION	An unknown error occurred.	A (Control Group)

Parameters

• You can also receive the parameter values for the assigned Variation through the variationDetail() method.

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

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

• Use the following functions to retrieve the values configured for the assigned Variation.

getString	Returns parameter values configured as STRING or JSON type.
getInt	Returns parameter values configured as NUMBER type as an Int.
getDouble	Returns parameter values configured as NUMBER type as a Double.
getBool	Returns parameter values configured as Boolean type.

Example

import "package:hackle/hackle.dart";

Decision decision = await HackleApp.variationDetail(42);
ParameterConfig config = decision.config;

String strValue = config.getString("parameter_key_string_type", "defaultValue");
String jsonValue = config.getString("parameter_key_json_type", "defaultValue");
int intValue = config.getInt("parameter_key_number_type", 0);
double doubleValue = config.getDouble("parameter_key_number_type", 0.0);
bool boolValue = config.getBool("parameter_key_boolean_type", false);