Flutter V3.1.X

Introduction

SDK overview

Welcome to the Flagship Flutter SDK documentation!

The following documentation helps you run Flagship on your Flutter app using our client library.

Feel free to contact us if you have any questions regarding this documentation.

SDK features

This SDK version will help you:

• Set a visitor ID
• Update visitor context
• Synchronize campaigns via the Decision API
• Get a flag value
• Send a hit to our Data Collect

Prequisites

• Flagship SDK supports Dart 2.12.0 minimum or higher
• Flagship is null safety

Good to know

• Latest Version
• Github repository
• 
• 
• Dart code supported

Getting Started

Our Flagship flutter SDK is available for distribution through pub.dev

Installing

Run this command:

flutter pub add flagship

This will add a line like this to your package's pubspec.yaml (and run an implicit dart pub get):

dependencies:
  flagship: ^3.1.2

Initialization

To run experiments with Flagship, you will need to start the SDK using:

start(String envId, String apiKey, {FlagshipConfig? config}) async

📘

You can get your own envId & API Key in the Flagship Platform.

1. Navigate to Settings⟶API Key & Settings
2. Copy the environment ID & API Key

Flagship use predefined context keys to help you retrieve datas in the reporting, those keys can be the language, Flagship version but can also be some device informations.

That's the reason you have to « wait » the device informations gathering process.

Here is an example on how to start the SDK:

// import package
import 'package:flagship/flagship.dart';

//////////////////////////////////////////////
/////// Start sdk with default options ///////
//////////////////////////////////////////////

await Flagship.start("your_env_id", "your_api_key");

//import package
import 'package:flagship/flagship.dart';

/////////////////////////////////////////////////////////////
// Create visitor when SDK is ready, using the statusListener
/////////////////////////////////////////////////////////////
    FlagshipConfig customConfig = ConfigBuilder()
        .withMode(Mode.DECISION_API)
        .withStatusListener((newStatus) {
          // When the status is Ready
          if (newStatus == Status.READY) {
            // Do things ...
          }
        })
        .withTimeout(2500)
        .withLogLevel(Level.ALL)
        .build();

    // Start SDK
    Flagship.start(
        "your_env_id", "your_api_key",
        config: customConfig);

Advanced Configuration

The sdk provides the FlagshipConfig object in the start function as an optional parameter where we can set the desired configuration

Decision Mode :

• ConfigBuilder withMode(Mode newMode)

DECISION_API

When the SDK is running in DecisionApi mode, the campaign assignments and targeting validation take place server-side. In this mode, each call to the fetchFlags method to refresh the flags will create an HTTP request.

BUCKETING

When the SDK is running in BUCKETING mode, the SDK downloads all the campaigns configurations at once in a single bucketing file so that variation assignment can be computed client-side by the SDK. This bucketing file is stored in cache and will only be downloaded again when campaign configurations are modified in the Flagship interface.

Timeout :
This delay only concerns the request for fetching campaigns under the API mode. If the API didn't answer during this interval of time, the default values will be returned from value function.

• ConfigBuilder withTimeout(int newTimeout)

📘

The unit of measure for the timeout is Millisecond.

statusListener :

This listener is called when SDK status has changed.

• ConfigBuilder withStatusListener(StatusListener listener)

logLevel :

ConfigBuilder withLogLevel(Level newLevel)

You can change log's level of detail during the runtime void setLoggerLevel(Level newLevel)

Polling Interval Time :

Only available for Bucketing Mode:

Define time interval between two bucketing updates.

• ConfigBuilder withBucketingPollingIntervals(int newPollingTime)

//////////////////////////////////////////////
/////// Start SDK with custom options  ///////
//////////////////////////////////////////////

// - timeout   = 2500 ms
// - level     = warning message
// - statusListener callback

FlagshipConfig customConfig = ConfigBuilder()
    .withMode(Mode.DECISION_API)
    .withStatusListener((newStatus) {
      // Do things when status change ...
    })
    .withTimeout(2500)
    .withLogLevel(Level.WARNING)
    .build();
    
// Start SDK
await Flagship.start("your_env_id", "your_api_key", config: customConfig);

Config Tracking Manager

• ConfigBuilder withTrackingConfig(TrackingManagerConfig trackingManagerConfig)

The SDK through the TrackingManager class report analytics event using batching process, each time a visitor emits a hit, the tracking manager will stack it in the event pool.

When the time interval batchIntervals is over or pool Maximum Size poolMaxSize is reached, the batch process is triggered and the pool emptied.

In the meantime, the caching process depends on the cache strategy adopted.

The advantages:

• Use less network traffic
• Avoid data loss
• Catch all hits that would fail

The TrackingManager stand on three options to setup

• Time Interval
  Time interval to process and send event through batch

🚧

The batchIntervals parameter is an integer, default value is 5 seconds

• Pool Max Size
  Specifies the maximum number of hit in the pool

🚧

The poolMaxSize parameter is an integer, default value is 10

• Cache Strategy

Define a strategy to adopt, we have two strategies represented by an enum BatchCachingStrategy.

1 - BATCH_CONTINUOUS_CACHING

Each time a visitor emits an event, this strategy duplicates events in cache using cacheHit (see InterfaceCache), on completion batching process the saved hits are removed from the cache.

Note: The SDK has a default cache implementation using a database

Note: recommended for client side applications

2 - BATCH_PERIODIC_CACHING

This strategy periodically make a copy in the cache of the existing event in the pool, those events will be removed once the batching process completed and succeed

Note: recommended for server-side applications

//////////////////////////////////////////////
/////// Start SDK with custom options  ///////
//////////////////////////////////////////////


// Create a config manager with a custom settings:
// - timeout   = 1500 ms
// - level     = warning message
// - statusListener callback
// - Time Intreval : 20
// - Maximum size pool : 20
// - Strategy : BATCH_CONTINUOUS_CACHING

// Create a custom tracking manager  
    var customTrackingConfig = TrackingManagerConfig(
        batchIntervals: 20,
        poolMaxSize: 20,
        batchStrategy: BatchCachingStrategy.BATCH_CONTINUOUS_CACHING);


// Create customConfig config manager 
    FlagshipConfig customConfig = ConfigBuilder()
        .withMode(Mode.DECISION_API)
        .withStatusListener((newStatus) {
          // Do things when status change ...
        })
        .withTimeout(1500)
        .withLogLevel(Level.WARNING)
        .withTrackingConfig(customTrackingConfig)
        .build();

// Start SDK with a custom configuration
    Flagship.start("your_env_id", "your_api_key", config: customConfig);
  }

Developer Usage Tracking

• ConfigBuilder withDisableDeveloperUsageTracking(bool disableDeveloperUsageTracking)

// Create config and disabled usage tracking 
   FlagshipConfig customConfig = ConfigBuilder().withDisableDeveloperUsageTracking(true)
        .build();
// Start SDK
    await Flagship.start("your_env_id", "your_api_key", config: customConfig);

🚧

In the start function the config parameter is optional, The SDK will run with default settings.

SDK Status

It's possible to get the current status via the method getStatus() from the Flagship class.

• static Status getStatus()

Return an enum that represent the current SDK status

List of the possible SDK status :

// Get the current status for the SDK
   var currentStatus = Flagship.getStatus();

// Using getStatus to check if the SDK is READY

// Create the visitor 
   var visitor = Flagship.newVisitor("user1",{"isVip":true});

// Fetch Flags the modifications 
   visitor.fetchFlags().whenComplete(() {
    
// Get the status and check the mode
   Status currentState =  Flagship.getStatus();
    if (currentState == Status.READY) {
      // The SDK is ready
    }
  });

onVisitorExposed

In some cases, you'll need to send informations about the exposition (When a flag has been seen by your visitor), like sending visitor and flag data to third parties.

To centralize it, we provide a callback in the configuration option of the SDK.

This callback is triggered each time the function visitorExposed is called and success.

-ConfigBuilder withOnVisitorExposed(OnVisitorExposed pOnVisitorExposed)

The OnVisitorExposed callback is a function with two parameters

typedef OnVisitorExposed = void Function(VisitorExposed visitorExposed, ExposedFlag fromFlag)?;

VisitorExposed

The class VisitorExposed give us the visitor's information

ExposedFlag

The class ExposedFlag give us the flag's information

For both class VisitorExposed & ExposedFlag use toJson() method to get the json representation .

// Inside the callBack we use toJson() method to get the json representation.
// This block is a part of confuguration builder, for more information 
// go to #flagship-configuration-options section
.withOnVisitorExposed((exposedUser, fromFlag) {
          // Get the json representation                  
          print(fromFlag.toJson());
          print(exposedUser.toJson());
        })
        
// Representation of VisitorExposed  
{
  "id": "visitor_1",
  "anonymousId": null,
  "context": {
    "sdk_firstTimeInit": false,
    "sdk_deviceLanguage": "fr_US",
    "sdk_deviceType": "Mobile",
    "sdk_deviceModel": "iPhone",
    "sdk_osName": "ios",
    "sdk_osVersionName": "ios",
    "sdk_fsVersion": "2.1.0,",
    "customer": "QA",
    "country": "FR"
  }
}

// Representation of ExposedFlag 
{
  "key": "btnColor",
  "value": "Green",
  "metadata": {
    "campaignId": "cfv24sokqu3h6tka0sv0",
    "variationGroupId": "cfv24sokqu3h6tka0t00",
    "variationId": "cfv24sokqu3h6tka0t10",
    "isReference": false,
    "campaignType": "ab",
    "slug": null
  }
}

📘

The onVisitorExposed callback is triggered ONLY when the visitorExpose() method is called and success.

Here is an example on how to use this callback:

• Example with Mixpanel integration

Create a visitor

Once Flagship SDK is initialized, you can create a visitor.

The Visitor instance is an object that lets you manage the context, activate experiments and track events.

• VisitorBuilder(this.visitorId, {this.instanceType = Instance.SINGLE_INSTANCE});

Visitor Builder methods:

Represent the visitor's initial context key/values used for targeting.

Context keys must be String, and values types must be one of the following: String, bool, int, double, Boolean, String.

• VisitorBuilder withContext(Map<String, Object> context)

• VisitorBuilder hasConsented(bool hasConsented)

Specify if the visitor has consented to personal data usage. When false some features will be deactivated. The default value is true.

• isAuthenticated(bool authenticated)

The visitorId will be considered as authenticated if true otherwise is anonymous.

Flagship use predefined context keys to help you retrieve datas in the reporting, those keys can be the location, IP but can also be some device informations.

That's the reason you have to « wait » the device informations gather process.

Here is an example on how to start the SDK and create visitor :

// import package
import 'package:flagship/flagship.dart';

//////////////////////////////////////////////
///////        Create visitor          ///////
//////////////////////////////////////////////

// Start SDK
await Flagship.start("your_env_id", "your_api_key");

Visitor visitor1 =
      Flagship.newVisitor("visitor_1")
              .withContext({"isVip": true})
              .hasConsented(true)
              .isAuthenticated(true).build();

// import package
import 'package:flagship/flagship.dart';

/////////////////////////////////////////////////////////////
// Create visitor when SDK is ready, using the statusListener
/////////////////////////////////////////////////////////////

    FlagshipConfig customConfig = ConfigBuilder()
        .withMode(Mode.DECISION_API)
        .withStatusListener((newStatus) {
          // When the status is Ready
          if (newStatus == Status.READY) {
            // Get the current visitor
            if (Flagship.getCurrentVisitor() == null) {
              // Create new visitor when the current visitor is null
              // By default the created visitor is a shared instance
              Flagship.newVisitor("user")
                  .withContext({"isVip": true})
                  .hasConsented(true)
                  .isAuthenticated(true)
                  .build();
            }
            // Fetch flags
            Flagship.getCurrentVisitor()?.fetchFlags().whenComplete(() {
              // Do things
            });
          }
        })
        .withTimeout(2500)
        .withLogLevel(Level.ALL)
        .build();

    // Start SDK
    Flagship.start(
        "your_env_id", "your_api_key",
        config: customConfig);

Get & Set the current visitor

Most of the time, your Flutter application will handle only 1 visitor at any given time.
For this use case, Flagship implement 2 useful methods to store the created visitor as the current singleton visitor instance.

static setCurrentVisitor(Visitor visitor)

Stores the current visitor instance created at the newVisitor.

// import package
import 'package:flagship/flagship.dart';

//////////////////////////////////////////
/////// set the current visitor //////////
//////////////////////////////////////////

// Create not shared instance visitor
Visitor newVisitor = Flagship.newVisitor("visitor_1", instanceType: Instance.NEW_INSTANCE)
    .withContext({"isVip": true})
    .hasConsented(true)
    .isAuthenticated(true)
    .build();

// Set as current visitor
Flagship.setCurrentVisitor(newVisitor);

static Visitor? getCurrentVisitor()

Return the current visitor instance stored when setting the current visitor.

// import package
import 'package:flagship/flagship.dart';

//////////////////////////////////////////
/////// Get the current visitor //////////
//////////////////////////////////////////

var visitor = Flagship.getCurrentVisitor();

🚧

This method returns a nullable Visitor (in case the current visitor has not been previously set).
Make sure to check whether it is null or not before using it.

Updating the visitor context

The visitor context is a property dataset that defines the current visitor of your app. This dataset is sent and used by the Flagship Decision API as targeting criteria for campaign assignment.

The following method from the Visitor instance allows you to set new context values matching the given keys.

void updateContext(String key, Object value)

Update the visitor context values, matching the given keys, used for targeting.

Only String, bool, int, double typed values are accepted.

void updateContextWithMap(Map<String, Object> context)

Update the visitor context values, matching the given keys, used for targeting.

Only String, bool, double and int type values are accepted.

📘

• User context keys must have a type of String
  • User context values must have a type of String, bool, double or int
  • User context keys and values are case sensitive

void updateFlagshipContext<T>(FlagshipContext flagshipContext, T value)

Update the context with a predefined context see FlagshipContext

// import package
import 'package:flagship/flagship.dart';

//////////////////////////////
/////// Update context ///////
//////////////////////////////

var currentVisitor = Flagship.getCurrentVisitor();

// Update context with key/value
currentVisitor?.updateContext("lastPurchaseDate", 1615384464);

// Update context with Map
currentVisitor?.updateContextWithMap({"isVip": true, "key1": 12.5, "key2": "title", "key3": 2});

// Update the location country
currentVisitor?.updateFlagshipContext(FlagshipContext.LOCATION_COUNTRY, "FRANCE");

// Update the carrier name
currentVisitor?.updateFlagshipContext(FlagshipContext.CARRIER_NAME, "SFR");

void clearContext()

Clear the visitor context values, used for targeting.

// Import package
import 'package:flagship/flagship.dart';

/////////////////////////////
/////// Clear context ///////
/////////////////////////////

var currentVisitor = Flagship.getCurrentVisitor();

currentVisitor?.clearContext();

Managing visitor campaigns and theirs flags

Fetching Flags

The fetchFlags() method of the visitor instance automatically calls the Flagship Decision API to run campaign assignments according to the current visitor context and retrieve applicable flags.

These flags are updated asynchronously when fetchFlags() is called.

/////////////////////////////////////////
///////     Fetch Flags           ///////
/////////////////////////////////////////

import 'package:flagship/flagship.dart';


// Get the current visitor
var currentVisitor = Flagship.getCurrentVisitor();
// Fetch Flags
currentVisitor?.fetchFlags().whenComplete(() {
  // The fetch is done.
  // If the panic mode is ON or the fetch fail for another reason
  // the value for flag will be a default value
});

Future<void> fetchFlags() async

This function will call the decision api and update all the campaigns flags from the server according to the visitor context.

Getting flags

Once the campaign has been assigned and fetched, all the flags are stored in the SDK.
You can retrieve these flags using the following functions from the Visitor instance:

////////////////////////////////
///////    Get Flag      ///////
////////////////////////////////

import 'package:flagship/flagship.dart';
import 'package:flagship/model/flag.dart';


// Get the current visitor
    var currentVisitor = Flagship.getCurrentVisitor();

// Fetch flags
    currentVisitor?.fetchFlags().whenComplete(() {
      // Ex: get flag for vip feature
      Flag flag = currentVisitor.getFlag("displayVipFeature",false);
    });

// The getFlag function can be directly called through the "currentVisitor" instance if you
// already fetched it elsewhere in the application

Flag getFlag<T>(String key, T defaultValue)

Retrieve a Flag object by its key. If no flag match the given key an empty flag will be returned. Call exists() to check if the flag has been found.

Getting flags current values

To retrieve flag current value, simply call value() method of the Flag object.

• dynamic value({bool visitorExposed: true})
  Returns the value from the assigned campaign variation or the Flag default value if the Flag does not exist, or if types are different.

import 'package:flagship/flagship.dart';
import 'package:flagship/model/flag.dart';

// Get the current visitor
    var currentVisitor = Flagship.getCurrentVisitor();

// Fetch flags
    currentVisitor?.fetchFlags().whenComplete(() {
      // Ex: get flag for vip feature
      Flag flag = currentVisitor.getFlag("displayVipFeature", false);

      // Use this flag value to enable displaying the vip feature
      bool shouldDisplayVipFeature = flag.value();
    });

📘

When the value of flag is null the value() method return the defaultValue

Getting flags campaigns metadata

You may need to send campaign's informations to a third-party for reporting and/or analytics purposes. The metadata method returns a dictionary with values you can use.

• FlagMetadata metadata()
  Return the campaign metadata or an empty object if the Flag doesn't exist or if the default value type does not correspond to the Flag type in Flagship.

import 'package:flagship/flagship.dart';
import 'package:flagship/model/flag.dart';

// Get the current visitor
    var currentVisitor = Flagship.getCurrentVisitor();

// Fetch flags
    currentVisitor?.fetchFlags().whenComplete(() {
      // Ex: get flag for vip feature
      Flag flag = currentVisitor.getFlag("displayVipFeature", false);

      // Use this flag value to enable displaying the vip feature
      bool shouldDisplayVipFeature = flag.value();
      
      // Use this flag to get the metadata      
        FlagMetadata metadata = flag.metadata();

    });

The metadata you can access to are the following one:

Report a Flag exposition

🚧

Deprecated

The userExposed method is deprecated since the version 2.1.0. please use visitorExposed instead.

By default when the method value() is called, the SDK considers that the visitor has seen your Flag unless you pass false to value(). In this last case, you will have to call the visitorExposed() method.

There are two options for exposing a visitor to a flag:
1 - Pass an visitorExposed = true parameter to the value() method.
2 - Use the following visitorExposed() method from the Flag instance.

• Future<void> visitorExposed() async

// Get the current visitor
    var currentVisitor = Flagship.getCurrentVisitor();

// Fetch flags
    currentVisitor?.fetchFlags().whenComplete(() {
      // Ex: get flag for vip feature
      Flag flag = currentVisitor.getFlag("displayVipFeature", false);

      // Use this flag value to enable displaying the vip feature with expose to false
      bool shouldDisplayVipFeature = flag.value(visitorExposed: false);

      // Expose this flag later in the code
      flag.visitorExposed();
    });

📘

Reminder

The onVisitorExposed is triggered when this callback is defined in configuration options
and the visitorExpose() method success.

Check if a Flag exists

• bool exists()
  This method will return true if a Flag has been returned by Flagship.

// Get the current visitor
    var currentVisitor = Flagship.getCurrentVisitor();

// Fetch flags
    currentVisitor?.fetchFlags().whenComplete(() {
      
     // Ex: get flag for vip feature and check if it exists
      bool isDisplayVipFeatureExists = currentVisitor.getFlag("do_not_exists", false).exists();
    });
  }

Managing visitor consent

The Visitor class provides a method to let you manage visitor consent for data privacy usage. When false the activation and hits will be disabled.

//////////////////////////////////////
/////// Manage visitor consent ///////
//////////////////////////////////////

// Create visitor with no consent
var visitor = Flagship.newVisitor(visitorIdController.text, visitorContext, hasConsented:false);
// Set the consent to true on run time
visitor.setConsent(true);

Experience Continuity

Dealing with anonymous and logged-in users, experience continuity allows you to maintain consistency between sessions and devices.

🚧

Make sure that the experience continuity option is enabled on the flagship platform before using those methods.

Authenticate

There are 2 ways to authenticate a visitor:

1. Set isAuthenticated to true when creating a new visitor
2. Use authenticate method of Visitor instance
   Authenticate anonymous visitor

• authenticateVisitor(String pVisitorId)

🚧

Because we have changed the visitor data, we have to call the fetchFlags method after calling this one to update the decision from Flagship.

The targeting / Flags could be different for the visitor.

Unauthenticate

This function change authenticated Visitor to anonymous visitor

• unAuthenticateVisitor()

🚧

Because we have changed the visitor datas, we have to call the fetchFlags method after calling this one to update the decision from Flagship.

The targeting / Flags could be different for the visitor.

code Example

Let's assume basic scenario to understand how things work:

1. Your visitor arrives on your app for the first time.

We need to initialize the visitor but as we don't know anything about this visitor, we'll create a random_Id. You can also specify some visitor context if necessary.

// Create visitor with random_Id
   Visitor visitor = Flagship.newVisitor("random_Id").withContext({"isVip": true}).build();

// Fetch flags
  visitor.fetchFlags().whenComplete(() {
    // .. Do things
  });

The actual random_Id will be what we call the anonymous id.

2. Your visitor is signing in.

To tell the SDK about this status modification, you'll have to call the authenticate function which takes the required visitor id as argument.

// Example
// You fetch the visitor_id from your DB
// let visitorId = db.getUserId();

// Authenticate
   visitor.authenticate("visitorId");

// Since your visitor has changed (is now logged-in)
// You have to check if the proper targeting and flags are set

  visitor.fetchFlags().whenComplete(() {
    // .. Do things
  });

The visitor is updated as authenticated, keeping the previous variations from campaigns that are still matched and thus gives you same flags as before being logged in.

3. Your visitor decides to sign out.

If you want to keep the same visitor experience, then you should do:

// Unauthenticate

  visitor.unauthenticate();

// Since your visitor has changed (is now logged-out)
// You have to check if the proper targeting and flags are set

  visitor.fetchFlags().whenComplete(() {
    // .. Do things
  });

Final implementation example

// Create a visitor

    Visitor visitor = Flagship.newVisitor("random_Id").withContext({"isVip": true}).build();

// Fetch flags

    visitor.fetchFlags().whenComplete(() {
      // ... Do things ....
    });


// You fetch the visitor_id from your DB
// let visitorId = db.getUserId();

// Call the authenticate function

    visitor.authenticate("visitorId");

// Fetch the flags to update the visitor decision

    visitor.fetchFlags().whenComplete(() {
      // ... Do things ....
    });

// If you want to unauthenticate the visitor

    visitor.unauthenticate();

// Fetch the flags to update the visitor decision

    visitor.fetchFlags().whenComplete(() {
      // ... Do things ....
    });

Managing visitor cache

The role of cache management is to avoid data lost and keep SDK working correctly in the offline mode. Also in the bucketing mode will prevent against the Re-allocation

Offline mode
The SDK use the last cached data relative to visitor (campaign assignations) and cache events analytics in order to report them later.

Re-allocation
In Bucketing mode the visitor keeps his initial variation chosen by the bucket process even if the allocation changes.

Flagship's architecture allows the client to set his own custom cache manager by implementing the interfaces IVisitorCacheImplementation and IHitCacheImplementation. see the configuration

📘

Flagship Flutter SDK provide a default cache manager implementation.

Interface IVisitorCacheImplementation

This protocol specifies the methods to implement in order to cache information visitor.

void cacheVisitor(String visitorId, String jsonString)

This method called after each fetchFlags. Must upsert the given visitor jsonString in the database.

Future<String> lookupVisitor(String visitoId)

This method is called right at visitor creation, return a jsonString corresponding to visitor.

void flushVisitor(String visitorId)

This method is called when the SDK needs to erase the visitor information corresponding to visitor ID in the database.

🚧

It will be called every time setConsent get false.

Interface IHitCacheImplementation

void cacheHits(Map<String, Object> hits)

This method will be called to cache hits depending on the cache strategy used.

Future<List<Map>> lookupHits()

This method will be called to load all hits from your database and trying to send them.

void flushHits(List<String> hitIds)

This method will be called to erase all hits in your database without exception.

void flushAllHits()

This method must remove all hits in the database without exception.

Final implementation example

// Implement IHitCacheImplementation
class CustomCacheHit with IHitCacheImplementation {
  @override
  void cacheHits(Map<String,Object> hits) {
     // Save the Map that represent {"hitId": {data hit}}
  }

  @override
  void flushAllHits() {
    // Remove all hits in database    
  }

  @override
  void flushHits(List<String> hitIds) {
    // Remove the hit's id given with List 
  }

  @override
  Future<List<Map>> lookupHits()async {
    // Return the saved hit in your database

  }
}

// Implement IVisitorCacheImplementation

class CustomVisitorCache with IVisitorCacheImplementation {
  @override
  void cacheVisitor(String visitorId, String jsonString) {
     // Save the json that represent the data information for visitorId
  }

  @override
  void flushVisitor(String visitorId) {
    // Remove the data for visitorId
  }

  @override
  Future<String> lookupVisitor(String visitoId) async {
    // Return the saved data to visitorId

  }
}

 // Create a config object and specify the custom hit and custom visitor
    var config = ConfigBuilder()
        .withCacheHitManager(CustomCacheHit())
        .withCacheVisitorManager(CustomVisitorCache())
        .build();
    
// Start the SDK with the config 
   await Flagship.start("envId", "apiKey", config: config);

Hit Tracking

This section helps send tracking and learn how to build hits in order to track campaign goals.

The different types of Hits are:

• Screen
• Page
• Transaction
• Item
• Event

They must all be built and sent with the following method of the visitor instance:

Future<void> SendHit(hit HitProtocol)

Common parameters

These parameters can be sent with any type of hit.

Hit types

Screen

This hit should be sent each time a visitor arrives on a new interface.

//////////////////////////
/////// Screen hit ///////
//////////////////////////

var visitor = Flagship.getCurrentVisitor();
// Send screen hit 
visitor?.sendHit(Screen(location: "My page"));

Page

This hit should be sent each time a visitor arrives on web page in an embedded web view

//////////////////////////
/////// Page  hit ///////
//////////////////////////

var visitor = Flagship.getCurrentVisitor();
// Send page hit 
visitor?.sendHit(Page(location: "https://www.my_domain_com/my_page"));

Transaction

This hit should be sent when a user complete a Transaction.

///////////////////////////////
/////// Transaction hit ///////
///////////////////////////////

var visitor = Flagship.getCurrentVisitor();
visitor?.sendHit(Transaction(
  transactionId   : "YOUR_TRANSACTION_ID",
  affiliation     : "GOAL_NAME", // The goal name set in Flagship campaign
  revenue         :	100,
  shipping        :	10,
  tax             :	5,
  currency        : "EUR",
  couponCode      : "discount",
  paymentMethod   : "Card",
  shippingMethod  : "postal",
  itemCount       : 2,
));

Item

This hit is linked to a transaction. It must be sent after the corresponding transaction.

////////////////////////
/////// Item hit ///////
////////////////////////

var visitor = Flagship.getCurrentVisitor();
visitor?.sendHit(Item(
  transactionId	: "YOUR_TRANSACTION_ID",
  name					: "item name",
  code					: "item code",
  price					: 10.5,
  quantity			: 5,
  category			: "item category"
));

Event

This hit can be anything you want: for example a click or a newsletter subscription.

/////////////////////////
/////// Event hit ///////
/////////////////////////

var visitor = Flagship.getCurrentVisitor();
visitor?.sendHit(Event(
  action		: "Event action", // The name of the goal defined in your campaign
  category	: EventCategory.Action_Tracking,
  label			: "custom label",
  value			: 2
));

Appendix

Predefined user context keys

The Flagship SDK contains predefined user context keys.

The keys marked as Yes in the Auto-set by SDK column will be automatically set, while the ones marked as No need to be set by the client.

They are nevertheless overridable at anytime. Then these predefined context keys-value pairs will be sent to the server and be editable in the Persona section of the Flagship platform.

Here you can see how a predefined key is used to filter a report in the Flagship interface: