What if flutter secure storage and get storage already have a key in the name when you try to write the new data to that key will it overwrite or else throw error ?

Flutter Storage Key Overwriting Behavior

When using Flutter Secure Storage or GetStorage with an existing key, the behavior is straightforward: the new data overwrites the existing value without throwing an error.

Flutter Secure Storage

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import 'package:flutter_secure_storage/flutter_secure_storage.dart';

final storage = FlutterSecureStorage();

// Writing data
await storage.write(key: 'auth_token', value: 'token_123');

// Overwriting the same key (no error thrown)
await storage.write(key: 'auth_token', value: 'new_token_456');

// Reading returns the latest value
String? token = await storage.read(key: 'auth_token');
print(token); // Output: new_token_456

GetStorage

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import 'package:get_storage/get_storage.dart';

final box = GetStorage();

// Writing data
box.write('username', 'john_doe');

// Overwriting the same key (no error)
box.write('username', 'jane_smith');

// Reading returns the latest value
String? username = box.read('username');
print(username); // Output: jane_smith

Comparison Table

Safe Update Pattern

If you need to check before overwriting:

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// Check before writing
Future<void> safeWrite(String key, String value) async {
  final storage = FlutterSecureStorage();

  // Check if key exists
  String? existingValue = await storage.read(key: key);

  if (existingValue != null) {
    print('Warning: Overwriting existing value');
  }

  await storage.write(key: key, value: value);
}

Key Management Best Practices

• Always handle null values when reading
• Use consistent key naming conventions
• Document your storage keys in constants
• Implement versioning for important keys

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class StorageKeys {
  static const String authToken = 'auth_token';
  static const String userId = 'user_id';
  static const String refreshToken = 'refresh_token';
}

Remember: Both storage solutions overwrite by default. Implement your own validation logic if you need to prevent accidental overwrites.