Object Serialization in Flutter: A Practical Approach

This article discusses the challenges of object serialization and deserialization in Flutter development, particularly when dealing with complex objects. While Flutter's built-in JsonCodec only supports primitive types (primitive, Map, List), the article explores why the commonly recommended json_serializable approach may not be ideal for certain use cases.

The authors present their solution: fish-serializable, a custom serialization library designed to address specific needs. The library's architecture is based on a ValueHolder class that acts as an intermediate storage for data, a FishSerializable interface that defines serialization behavior, and a JsonSerializer for JSON-specific operations.

Key challenges addressed include: Flutter's lack of reflection support (dart:mirrors is disabled), difficulties with generic type matching and nested generics, and the need for a more efficient solution than existing alternatives. The article details the design decisions, implementation strategies, and practical considerations for building a robust serialization system in Flutter.

The solution includes an IntelliJ plugin (fish-serializable-intelij-plugin) to automate code generation, making it more developer-friendly. The authors note that this approach is already being used in production at Xianyu (Alibaba's second-hand trading platform) and is planned for open-source release.