Flutter Persistent Storage Solutions

Flutter offers multiple ways to store data persistently — depending on the type, size, and frequency of data access. Here are the most commonly used solutions:

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1. SQFlite – SQLite Database for Flutter

Use Case:
Ideal for storing structured, relational data that requires queries, indexing, or transactions.

Details:
The sqflite package provides a simple and efficient way to work with an SQLite database directly from Flutter.
SQLite is a lightweight relational database that stores data locally on the device.

Steps:

• Use the path package to locate or create the database file in the appropriate directory supported by the platform (Android, iOS, Web, etc.).
• Then, use sqflite to open the database, define tables, and perform CRUD operations.

Reference:
🔗 SQLite Tutorial

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2. XML-based Key-Value Store – shared_preferences

Use Case:
Best suited for lightweight, primitive data (e.g., user settings, app theme, login status, tokens).

Details:
The shared_preferences plugin provides persistent storage for simple data types such as strings, integers, and booleans.
Internally, it stores data in an XML-based key-value format on Android and in UserDefaults on iOS.

Example Use Cases:

• Saving user preferences
• Remembering “dark mode” settings
• Caching login session tokens

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3. File Storage

Use Case:
Used for storing files, logs, serialized data, or large custom data objects.

Packages Used:

• path_provider → To locate system directories
• dart:io → To perform file read/write operations

Common Directories:

1. Cache Directory
   • Use getCacheDir()
   • Temporary directory at the device level.
   • Data here can be cleared automatically by the system when storage is low.
2. Application’s Private Directory
   • Use getApplicationDocumentsDirectory()
   • Private to the app and not accessible by other apps.
   • Automatically deleted when the app is uninstalled.

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✅ Summary:

Storage Type	Package	Data Type	Persistence	Ideal Use
SQFlite	sqflite	Structured (tables)	Long-term	Complex relational data
Shared Preferences	shared_preferences	Key-Value (primitive)	Long-term	Settings, flags
File Storage	path_provider, dart:io	Files & Objects	Long-term	Custom or binary data

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