Decide methods for the Flutter SDK

26 min

Use the decide methods to return feature flag decisions for a user. Each decision includes whether the flag is enabled and which variation the user receives.

Decide

Returns a decision for a specific feature flag and user.

Minimum SDK version – v1.0.1+

Description

The decide method handles the variation decision for an individual experiment. It returns a decision result for a flag key for a user in an OptimizelyDecision object and contains the data required to deliver the flag rule.

This method ensures that Feature Experimentation properly buckets the user in experiment analytics, and you should use it if there is no need for pre-rendering decisions.

Decide is a method of the UserContext object. See OptimizelyUserContextOptimizelyUserContext for details.

See the `OptimizelyDecision`OptimizelyDecision documentation for details of the returned decision object.

Parameters

The following table describes parameters for the decide method:

Parameter	Type	Description
key	String	The key of the feature flag.
options (optional)	Set<OptimizelyDecideOption>	Set of OptimizelyDecideOption enums.

Returns

The decide method returns an OptimizelyDecision object. See OptimizelyDecisionOptimizelyDecision.

If the method encounters a critical error (SDK not ready, invalid flag key, and so on), it returns a decision with a null variationKey field and populates the reasons field with error messages (regardless of the OptimizelyDecideOption.INCLUDE_REASONS option).

Example decide

Map<String, dynamic> attributes = {};
attributes["logged_in"] = true;
var user = await flutterSDK.createUserContext(userId: "user123", attributes: attributes);

var decideResponse = await user!.decide("product_sort");

// variation. if null, decision fail with a critical error
var variationKey = decideResponse.decision!.variationKey;

// flag enabled state:
var enabled = decideResponse.decision!.enabled;

// all variable values
var variables = decideResponse.decision!.variables;

// String variable value
var vs = variables["sort_method"] as String;

// Boolean variable value
var vb = variables["k_boolean"] as bool;

// flag key for which decision was made
var flagKey = decideResponse.decision!.flagKey;

// user for which the decision was made
var userContext = decideResponse.decision!.userContext;

// reasons for the decision
var reasons = decideResponse.decision!.reasons;

Side effect

Invokes the decide notification listenerdecide notification listener if this listener is enabled.

Decide all

Returns decisions for all active (unarchived) flags for a user.

Minimum SDK version – 1.0.1

Description

Use the decide all method to retrieve decisions for all active flags before rendering content. This is particularly useful when you need to serve the correct cached version of your page or component based on the user's variation. For example when using an edge workeredge worker or cloud functioncloud function.

Key features

Pre-rendering decision – Lets you know all variation assignments ahead of time.

Cache control – Lets you serve the correct cached content based on the user's pre-determined variations.

Delay experiment tracking – Use DISABLE_DECISION_EVENT to prevent the SDK from recording a decision before the user sees the feature. This ensures that participation is only tracked when the experience is delivered.

CMAB support – For CMAB experiments (SDK v3.4.0+), decisions are automatically cached to reduce latency. The cache is invalidated when CMAB attributes change or TTL expires. Use CMAB-specific decide options (ignoreCmabCache, invalidateUserCmabCache, resetCmabCache) to override default caching behavior. See CMAB cache control.

Parameters

The following table describes parameters for the decide all method:

Parameter	Type	Description
options (optional)	Set<OptimizelyDecideOption>	Set of OptimizelyDecideOption enums.

Returns

Returns a map of OptimizelyDecisions. See OptimizelyDecisionOptimizelyDecision.

If the method fails for all flags (for example, the SDK is not ready or the user context is invalid), it returns a decision response with success status false, and reason and decision as null objects. If the method detects an error for a specific flag, it returns error messages in the reasons field of the decision for that flag.

Example decideAll

// make decisions for all active (unarchived) flags in the project for a user
Set<OptimizelyDecideOption> options = const { OptimizelyDecideOption.enabledFlagsOnly };
var decisionsResponse = await user!.decideAll(options);

var decisionMap = decisionsResponse.decisions;
var decisionForFlag1 = decisionMap["flag_1"];

Side effect

Invokes the DECISION notification listenernotification listener for each decision, if this listener is enabled.

Decide for keys

Returns a map of flag decisions for specified flag keys.

Minimum SDK version – v1.0.1+

Description

Returns a map of decisions for the specified flag keys.

Parameters

The following table describes parameters for the decide for keys method:

Parameter	Type	Description
keys	Array	Array of string flag keys.
options (optional)	Set<OptimizelyDecideOption>	Array of OptimizelyDecideOption enums.

Returns

Returns a map of OptimizelyDecisions. For information, see OptimizelyDecisionOptimizelyDecision.

If the method fails for all flags (for example, the SDK is not ready or the user context is invalid), it returns a decision response with success status false, reason and decision as null objects. If the method detects an error for a specific flag, it returns error messages in the reasons field of the decision for that flag.

Example decideForKeys

var keys = ["flag-1", "flag-2"];
var decisionsResponse = await user!.decideForKeys(keys);

var decisionMap = decisionsResponse.decisions;
var decision1 = decisionMap["flag_1"];
var decision2 = decisionMap["flag_2"];

Side effect

Invokes the decision notification listenerdecision notification listener for each decision, if this listener is enabled.

Decide Async

The decide async methods are the asynchronous version of the synchronous decide methods. Each decision includes whether the flag is enabled and which variation the user receives.

Fetch decisions asynchronously for all active (unarchived) flags for a user.

Minimum SDK version – v3.4.0+

Example decideAsync

Map<String, dynamic> attributes = {};
attributes["logged_in"] = true;
var user = await flutterSDK.createUserContext(userId: "user123", attributes: attributes);

var decideResponse = await user!.decideAsync("product_sort");

// variation. if null, decision fail with a critical error
var variationKey = decideResponse.decision!.variationKey;

// flag enabled state:
var enabled = decideResponse.decision!.enabled;

// reasons for the decision
var reasons = decideResponse.decision!.reasons;

Example decideAllAsync

// make decisions for all active (unarchived) flags in the project for a user
Set<OptimizelyDecideOption> options = const { OptimizelyDecideOption.enabledFlagsOnly };
var decisionsResponse = await user!.decideAllAsync(options);

var decisionMap = decisionsResponse.decisions;
var decisionForFlag1 = decisionMap["flag_1"];

Example decideForKeysAsync

var keys = ["flag-1", "flag-2"];
var decisionsResponse = await user!.decideForKeysAsync(keys);

var decisionMap = decisionsResponse.decisions;
var decision1 = decisionMap["flag_1"];
var decision2 = decisionMap["flag_2"];

OptimizelyDecideOption

The following table lists the OptimizelyDecideOption enum with an explanation what happens if you set them. In addition to setting these options individually for a decide method, you can also set them as global defaults when you instantiate the Optimizely client. See Initialize Flutter SDKInitialize Flutter SDK.

OptimizelyDecideOption enum	If set
OptimizelyDecideOption.DISABLE_DECISION_EVENT	Prevents the SDK from dispatching an impression event when serving a variation. This disables decision tracking on the Optimizely Experiment Results page and the decision notification listener.
OptimizelyDecideOption.ENABLED_FLAGS_ONLY	Returns decisions only for flags that are currently enabled. Used with the decide all method and decide for keys method. When this option is not set, the Android SDK returns all decisions regardless of whether the flag is enabled.
OptimizelyDecideOption.IGNORE_USER_PROFILE_SERVICE	Bypasses the user profile service (both lookup and save) for the decision. When this option is not set, user profile service overrides audience targeting, traffic allocation, and experiment mutual exclusion groups.
OptimizelyDecideOption.INCLUDE_REASONS	Adds log messages to the reasons field of the decision. Critical errors are always returned, even if this option is not set.
OptimizelyDecideOption.EXCLUDE_VARIABLES	Excludes flag variable values from the decision result. Use this option to minimize the returned decision by skipping large JSON variables.
OptimizelyDecideOption.IGNORE_CMAB_CACHE	Bypasses the CMAB cache and fetches a fresh decision from the CMAB service. Use when you need real-time decisions that reflect the latest context.
OptimizelyDecideOption.INVALIDATE_USER_CMAB_CACHE	Removes the cached CMAB decision for this user and experiment before making the decision. Use when user context has changed significantly and you want to ensure a fresh decision.
OptimizelyDecideOption.RESET_CMAB_CACHE	Clears all entries from the CMAB cache before making the decision. Use sparingly for testing or cache corruption scenarios.

The following code sample shows how to implement the OptimizelyDecideOption:

// Set options in a decide call
var flutterSDK = OptimizelyFlutterSdk("YOUR_SDK_KEY"); // Replace with your SDK key
var response = await flutterSDK.initializeClient();

// Flag decision
var user = await flutterSDK.createUserContext(userId: "user123");
Set<OptimizelyDecideOption> options = {};
options.add(OptimizelyDecideOption.disableDecisionEvent);
var decisions = user!.decideAll(options);

Best practices

Early and late invocation

Use the decide all method early in your application's rendering process to load the correct cached content. For example, on the CDN with an Edge SDK.

Use the decide method at the point of user interaction or when you must ensure Feature Experimentation records the decision in your experiment analytics.

Combining methods – When using the decide and decide all methods, always pair the decide all method with the decide method for each experiment the user encounters. This prevents discrepancies between served content and analytics data.

Parameter management – Ensure you use the DISABLE_DECISION_EVENT option with the decide all method to avoid premature bucketing, then use the decide method to handle the decision event when the user experiences the content.

CMAB cache control

Minimum SDK version – v3.4.0+

For Contextual Multi-Armed Bandit (CMAB) experiments, the Flutter SDK automatically caches variation assignments to reduce latency and API calls. The cache stores decisions based on user ID, experiment ID, and CMAB attribute values.

Automatic cache invalidation

The cache is automatically invalidated when

The cached entry's TTL expires (default: 30 minutes).

CMAB attribute values change for a user (detected through attribute hash comparison).

Manual cache control

Use CMAB-specific decide options to control cache behavior on a per-decision basis.

// Initialize Flutter SDK with default CMAB configuration
// Default cache size: 100, cache timeout: 1800 seconds (30 minutes)
var flutterSDK = OptimizelyFlutterSdk(
  SDK_KEY,
  cmabConfig: CmabConfig(), // Uses defaults
);

// Example 1: Use default cmab and caching logic
try {
	var response = await flutterSDK.initializeClient();
  var userContext = await flutterSDK.createUserContext(
      userId: 'user_123',
      attributes: {
        'country': 'us'
      },
    );
  var decision = await userContext.decideAsync(
        "cmab_flag_key",
        {OptimizelyDecideOption.ignoreUserProfileService},
      );
} 

// Example 2: Ignore CMAB cache (bypass cache, make fresh request).
try {
  var decision = await userContext.decideAsync(
        "cmab_flag_key",
        {
          OptimizelyDecideOption.ignoreCmabCache,
          OptimizelyDecideOption.ignoreUserProfileService,
        },
      );
} 

// Example 3: Invalidate cache when user context changes significantly
try {
  var decision = await userContext.decideAsync(
        "cmab_flag_key",
        {
          OptimizelyDecideOption.invalidateUserCmabCache,
          OptimizelyDecideOption.ignoreUserProfileService,
        },
      );
} 

// Example 4: Reset entire CMAB cache (use sparingly)
try {
  var decision = await userContext.decideAsync(
        "cmab_flag_key",
        {
          OptimizelyDecideOption.resetCmabCache,
          OptimizelyDecideOption.ignoreUserProfileService,
        },
      );
}

Important

To retrieve a CMAB decision, you must use the decideAsync method. The decide method does not fetch CMAB decisions to avoid blocking the user.

CMAB decision reasons

When using includeReasons, CMAB-related information display in the decision's reasons field.

try {
	var decision = await userContext.decideAsync(
        "cmab_flag_key",
        {
          OptimizelyDecideOption.resetCmabCache,
          OptimizelyDecideOption.ignoreUserProfileService,
          OptimizelyDecideOption.includeReasons
        },
      );
	print("[decide] reasons: ${decision.reasons}")
	// Examples:
  // User (user123) does not fall into cmab traffic allocation in experiment (exp_1).
  // CMAB is not supported in sync mode.
  // Failed to fetch CMAB data for experiment (exp_2).
}

Configure cache settings

// Create CMAB service with custom cache and prediction endpoint
var customCmabConfig = CmabConfig(
    cacheSize: 50, // Set cache size (default: 100)
    cacheTimeoutInSecs: 120, // Set TTL in seconds (default: 1800 = 30 minutes)
    predictionEndpoint: "https://prediction.cmab.com/predict/{ruleId}" // Set your custom prediction endpoint template
)
        
// Initialize client with custom cmab config
var flutterSDK = OptimizelyFlutterSdk(
  SDK_KEY,
  cmabConfig: customCmabConfig, 
);

Configure CMAB cache settings (size, TTL) and prediction endpoint at client initialization time. See Initialize Flutter SDKInitialize Flutter SDK for details.

Source files

The language and platform source files containing the implementation for Flutter (Android) are at Optimizely.java and Flutter (Swift) are at OptimizelyClient.swift .