# WCDB — WeChat Cross-Platform Database Framework

> A high-performance, cross-platform database framework developed by WeChat, built on SQLite with ORM, encryption, repair, and migration capabilities.

## Install

Save as a script file and run:

# WCDB — WeChat Cross-Platform Database Framework

## Quick Use
```swift
// Swift (iOS)
import WCDBSwift

let database = Database(at: "path/to/db")
try database.create(table: "messages", of: Message.self)
try database.insert(message, intoTable: "messages")
let results: [Message] = try database.getObjects(fromTable: "messages")
```

## Introduction
WCDB is an efficient, complete, and easy-to-use mobile database framework created by the WeChat team at Tencent. It wraps SQLite with an ORM layer, built-in encryption via SQLCipher, automatic corruption repair, and schema migration tools. WCDB powers the database layer inside WeChat, handling billions of records across its user base.

## What WCDB Does
- Provides a language-integrated ORM for Swift, Objective-C, Java, and Kotlin
- Encrypts databases transparently via an integrated SQLCipher layer
- Repairs corrupted database files automatically with its built-in recovery tool
- Supports schema migration without manual ALTER TABLE statements
- Offers full-text search using the FTS5 module with a simplified API

## Architecture Overview
WCDB layers an ORM, connection pooling, and a CRUD interface on top of a customized SQLite build. The framework compiles SQLCipher into the same binary for seamless encryption. A write-ahead logging (WAL) mode and connection pool allow concurrent read/write access. The repair module can reconstruct a valid database from a corrupted file by reading raw B-tree pages.

## Self-Hosting & Configuration
- Add WCDB via CocoaPods, Swift Package Manager, or Gradle for Android
- Encryption is enabled by passing a cipher key when opening the database
- Schema migrations are declared in code and applied automatically on open
- Enable WAL mode for better concurrent read/write performance (on by default)
- Configure the repair module to run automatically when corruption is detected

## Key Features
- Integrated SQLCipher encryption with no separate dependency
- Automatic database repair recovers data from corrupted files
- ORM maps class properties to columns with compile-time type safety
- Connection pool with reader-writer separation for concurrent access
- Full-text search with Chinese tokenizer support

## Comparison with Similar Tools
- **Raw SQLite** — requires manual SQL strings; WCDB provides ORM and encryption out of the box
- **Realm** — custom storage engine; WCDB stays on SQLite for broad compatibility
- **Room (Android)** — annotation-based ORM without encryption or repair; WCDB includes both
- **FMDB** — thin Objective-C wrapper; WCDB adds ORM, encryption, migration, and repair

## FAQ
**Q: Is WCDB only for WeChat?**
A: No. It is a general-purpose open-source framework usable in any iOS or Android application.

**Q: Does WCDB support Kotlin Multiplatform?**
A: WCDB has native SDKs for iOS (Swift/ObjC) and Android (Java/Kotlin). It is not a Kotlin Multiplatform library.

**Q: How does the repair feature work?**
A: WCDB reads raw SQLite B-tree pages and reconstructs a valid database, salvaging as much data as possible from the corrupt file.

**Q: Can I use WCDB without encryption?**
A: Yes. Encryption is optional; omit the cipher key to use a plain SQLite database.

## Sources
- https://github.com/Tencent/wcdb
- https://tencent.github.io/wcdb

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Source: https://tokrepo.com/en/workflows/69160781-429a-11f1-9bc6-00163e2b0d79
Author: Script Depot