mostly_good_metrics_flutter 0.2.5

Official Flutter SDK for MostlyGoodMetrics - Simple, privacy-focused analytics for your applications.

MostlyGoodMetrics Flutter SDK

A lightweight Flutter SDK for tracking analytics events with MostlyGoodMetrics.

Requirements

• Flutter 3.10+
• Dart 3.0+

Platform Support

Platform	Supported
iOS	Yes
Android	Yes
Web	Yes
macOS	Yes
Windows	Yes
Linux	Yes

Installation

Add the package to your pubspec.yaml:

dependencies:
  mostly_good_metrics_flutter: ^0.1.0

Then run:

flutter pub get

Quick Start

1. Initialize the SDK

Initialize once at app startup (typically in main.dart):

import 'package:flutter/material.dart';
import 'package:mostly_good_metrics_flutter/mostly_good_metrics_flutter.dart';

void main() async {
  WidgetsFlutterBinding.ensureInitialized();

  await MostlyGoodMetrics.configure(
    MGMConfiguration(apiKey: 'mgm_proj_your_api_key'),
  );

  runApp(MyApp());
}

2. Track Events

// Simple event
MostlyGoodMetrics.track('button_clicked');

// Event with properties
MostlyGoodMetrics.track('purchase_completed', properties: {
  'product_id': 'SKU123',
  'price': 29.99,
  'currency': 'USD',
});

3. Identify Users

// Set user identity
await MostlyGoodMetrics.identify('user_123');

// Reset identity (e.g., on logout)
await MostlyGoodMetrics.resetIdentity();

That's it! Events are automatically batched and sent.

Configuration Options

For more control, pass additional configuration:

await MostlyGoodMetrics.configure(
  MGMConfiguration(
    apiKey: 'mgm_proj_your_api_key',
    baseUrl: 'https://mostlygoodmetrics.com',
    environment: 'production',
    appVersion: '1.0.0', // Required for install/update tracking
    maxBatchSize: 100,
    flushInterval: 30,
    maxStoredEvents: 10000,
    enableDebugLogging: kDebugMode,
    trackAppLifecycleEvents: true,
  ),
);

Option	Default	Description
apiKey	Required	Your MostlyGoodMetrics API key
baseUrl	https://mostlygoodmetrics.com	API endpoint
environment	"production"	Environment name
appVersion	-	App version string (required for install/update tracking)
maxBatchSize	100	Events per batch (1-1000)
flushInterval	30	Auto-flush interval in seconds
maxStoredEvents	10000	Max cached events
enableDebugLogging	false	Enable debug output
trackAppLifecycleEvents	true	Auto-track lifecycle events

Automatic Events

When trackAppLifecycleEvents is enabled (default), the SDK automatically tracks:

Event	When	Properties
$app_installed	First launch after install	-
$app_updated	First launch after version change	previous_version, current_version
$app_opened	App started	-
$app_foregrounded	App became active	-
$app_backgrounded	App went to background	-

Event Naming

Event names must:

• Start with a letter (or $ for system events)
• Contain only alphanumeric characters and underscores
• Be 255 characters or less

// Valid
MostlyGoodMetrics.track('button_clicked');
MostlyGoodMetrics.track('PurchaseCompleted');
MostlyGoodMetrics.track('step_1_completed');

// Invalid (will throw MGMError)
MostlyGoodMetrics.track('123_event');      // starts with number
MostlyGoodMetrics.track('event-name');     // contains hyphen
MostlyGoodMetrics.track('event name');     // contains space

Properties

Events support various property types:

MostlyGoodMetrics.track('checkout', properties: {
  'string_prop': 'value',
  'int_prop': 42,
  'double_prop': 3.14,
  'bool_prop': true,
  'list_prop': ['a', 'b', 'c'],
  'nested': {
    'key': 'value',
  },
});

Limits:

• Nesting depth: max 3 levels

Manual Flush

Events are automatically flushed periodically and when the app backgrounds. You can also trigger a manual flush:

await MostlyGoodMetrics.flush();

To check pending events:

final count = await MostlyGoodMetrics.getPendingEventCount();
print('$count events pending');

To clear pending events:

await MostlyGoodMetrics.clearPendingEvents();

Session Management

The SDK automatically generates a new session ID when:

• The SDK is configured
• resetIdentity() is called
• startNewSession() is called

// Start a new session manually
await MostlyGoodMetrics.startNewSession();

// Access current session ID
final sessionId = MostlyGoodMetrics.sessionId;

Automatic Behavior

The SDK automatically:

• Persists events to local storage, surviving app restarts
• Batches events for efficient network usage
• Flushes on interval (default: every 30 seconds)
• Flushes on background when the app goes to background
• Retries on failure for network errors (events are preserved)
• Persists user ID across app launches
• Generates session IDs per app launch

Error Handling

The SDK throws MGMError for validation errors:

try {
  MostlyGoodMetrics.track('invalid-event-name');
} on MGMError catch (e) {
  print('Error type: ${e.type}');
  print('Message: ${e.message}');
}

Error types:

• MGMErrorType.notConfigured - SDK not configured
• MGMErrorType.invalidEventName - Invalid event name
• MGMErrorType.invalidProperties - Invalid properties (too deeply nested)
• MGMErrorType.networkError - Network failure
• MGMErrorType.storageError - Storage failure
• MGMErrorType.rateLimited - API rate limited

Debug Logging

Enable debug logging to see SDK activity:

await MostlyGoodMetrics.configure(
  MGMConfiguration(
    apiKey: 'mgm_proj_your_api_key',
    enableDebugLogging: true,
  ),
);

Output example:

[MostlyGoodMetrics] Configuring MostlyGoodMetrics SDK
[MostlyGoodMetrics] Tracked event: button_clicked
[MostlyGoodMetrics] Flushing 5 events
[MostlyGoodMetrics] Successfully sent 5 events

Running the Example

cd example
flutter pub get
flutter run

Testing

To run the tests:

flutter test

License

MIT