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Question1 answer1,000 followingPosted 21 Feb 2025, 23:17 UTC118.9K views2,140 votes

DetachedInstanceError when accessing relationship after session close in SQLAlchemy

Goal Determine the safest lazy‑loading configuration for ORM relationships that are serialized to JSON in a stateless web API while keeping response size predictable and avoiding DetachedInstanceError. Constraints The API creates a short‑lived Session per request and closes it before serialization. Relationships may be accessed multiple times during serializ

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sqlalchemy

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Question1 answer3,061 followingPosted 29 Feb 2024, 01:43 UTC26.4K views540 votes

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DetachedInstanceError when accessing lazy-loaded relationship after session close

Problem Context When a SQLAlchemy Session is closed, accessing a lazy-loaded relationship on an object raises sqlalchemy.orm.exc.DetachedInstanceError . Goal Determine whether the occurrence of DetachedInstanceError signals a performance bottleneck in session handling before applying optimizations such as eager loading or session configuration changes. Const

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detachedinstanceerror lazy-loading

sqlalchemy