python type_error ai_generated true

TypeError: Object of type User is not JSON serializable

ID: python/sqlalchemy-json-serialization-error

Also available as: JSON · Markdown · 中文
80%Fix Rate
87%Confidence
0Evidence
2024-03-25First Seen

Version Compatibility

VersionStatusIntroducedDeprecatedNotes
1.4.x active — — —
2.0.x active — — —

Root Cause

Trying to serialize SQLAlchemy model instances directly with json.dumps() without a custom encoder.

generic

中文

尝试直接用 json.dumps() 序列化 SQLAlchemy 模型实例，而没有自定义编码器。

Workarounds

  1. 90% success 
    Use a custom encoder: class UserEncoder(json.JSONEncoder): def default(self, obj): if isinstance(obj, User): return {'id': obj.id, 'name': obj.name} return super().default(obj)
  2. 85% success 
    Convert to dict first: user_dict = {c.name: getattr(user, c.name) for c in user.__table__.columns}

Dead Ends

Common approaches that don't work:

  1. 80% fail

    Returns the object's string representation, not the data.

  2. 70% fail

    Converts all non-serializable objects to strings, losing structure.