Planned lessonJNR-032-L05

Open Session in View: why to turn it off

On This Lesson 4 topics

This lesson is planned. The outline below lists the topics it will cover. The full lesson has not been published yet.

In this lesson

understand and disable Open Session in View (OSIV).

OSIV keeps the persistence context open until the HTTP response is written.
It hides LazyInitializationException, but lets queries run in controllers and JSON serialization.
That means unplanned N+1 and a database connection held for the whole request.
Spring Boot enables it by default (with a startup warning).
Set spring.jpa.open-in-view=false and load data explicitly in services.

Draft outline details

yaml

spring:
  jpa:
    open-in-view: false

What does OSIV hide?

Show answer

Lazy loading outside the service layer.

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