Http message conversion not finding Jackson JDK8 module in context [SPR-13049]

[spring-projects-issues]

John Franco opened SPR-13049 and commented

Despite having a Jackson JDK 8 module bean available in the context, deserializing a request having an Optional<String> field fails with an error indicating that the object mapper in use does not have the module installed. The attached git bundle has a maven project and a unit test to reproduce the problem. The unit test demonstrates that the object mapper available from the context does have the module installed (by deserializing a JSON string into an object having an Optional<String> field), which seems to indicate that the http message handling is using a different object mapper that doesn't have the module installed.

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Affects: 4.1.6

Attachments:

• spring-jackson-jdk8-bug.bundle (6.96 kB)
• spring-jackson-jdk8-bug.bundle (6.04 kB)

Issue Links:

• Automatically register Jackson's JDK 8 module when available [SPR-12983] #17574 Automatically register Jackson's JDK 8 module when available

[spring-projects-issues]

Juergen Hoeller commented

We're only registering Jackson's general JDK 8 module by default as of Spring 4.2, so I suppose we're talking about a manually registered module here... with multiple ObjectMappers in use at runtime, and only one of them having the manual module registration applied?

Juergen

[spring-projects-issues]

John Franco commented

The code registers the module as a bean in the application context, which the documentation describes as a way to make the module available globally. I think the worse problem is that the object mapper in use by the MVC stack for deserializing requests is not picking up such globally-registered modules. Why doesn't the MVC stack just use the global object mapper bean? That seems the simplest way to let REST controllers customize their JSON handling.

[spring-projects-issues]

Sébastien Deleuze commented

ObjectMapper customization by providing a bean is the Spring Boot approach. Regular Spring MVC application, or Spring Boot applications using @EnableWebMvc should customize the message converters as described in this article.

Could you check what kind of web configuration your application is using?

[spring-projects-issues]

John Franco commented

Hello, thank you for responding. I've read the article and added a Jackson2ObjectMapperBuilder bean to the application context following the example at https://github.com/sdeleuze/spring-jackson-demo/blob/master/src/main/java/demo/Application.java. The deserialization still fails. I'll attach an updated git bundle. Would you prefer that I submit my code in another form?

The code is using annotation-driven configuration. The main class is ReproServerConfiguration.java in the git bundle.

[spring-projects-issues]

Sébastien Deleuze commented

I will have a look, thanks.

[spring-projects-issues]

Sébastien Deleuze commented

I had a look to your sample project, you are using @EnableWebMvc that disables Spring Boot Web autoconfiguration. Just remove @EnableWebMvc and your test will pass.