[jira] [Assigned] (SLING-12359) Extend records support

["Stefan Seifert (Jira)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/SLING-12359?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Stefan Seifert reassigned SLING-12359:
--------------------------------------

    Assignee: Stefan Seifert
    Priority: Major  (was: Blocker)

> Extend records support
> ----------------------
>
>                 Key: SLING-12359
>                 URL: https://issues.apache.org/jira/browse/SLING-12359
>             Project: Sling
>          Issue Type: Improvement
>          Components: Sling Models
>    Affects Versions: Models Implementation 1.6.4
>            Reporter: Herman Ciechanowiec
>            Assignee: Stefan Seifert
>            Priority: Major
>             Fix For: Models Implementation 1.6.6
>
>
> Java 14 introduced support for record classes, and Apache Sling 12 by default runs with Java 17, allowing the use of records.
> Although Apache Sling 12 supports record classes, the current latest version of Apache Sling Models Implementation does not fully support injection in relation to records. Specifically, for records, the Apache Sling Models Implementation *does* support constructor injection similarly to a usual class if there is an *explicit* constructor annotated with `javax.inject.Inject`:
> {code:java}
> @Model(
>         adaptables = {Resource.class, SlingHttpServletRequest.class},
>         defaultInjectionStrategy = DefaultInjectionStrategy.REQUIRED
> )
> public record StudentModel(String name, int age) {
>     @Inject
>     public StudentModel(
>             @ValueMapValue(name = "name") @Default(values = "unknown")
>             String name, 
>             @ValueMapValue(name = "age") @Default(intValues = 0)
>             int age
>     ) {
>         this.name = name;
>         this.age = age;
>     }
> }
> {code}
> However, for records, Apache Sling Models Implementation *does not* support constructor injection if there is an *implicit* constructor. Such a constructor cannot be annotated with `javax.inject.Inject` and will not be picked up during injection. Therefore, such a Sling Model will not be instantiated at all:
> {code:java}
> @Model(
>         adaptables = {Resource.class, SlingHttpServletRequest.class},
>         defaultInjectionStrategy = DefaultInjectionStrategy.REQUIRED
> )
> public record StudentModel(
>         @ValueMapValue(name = "name") @Default(values = "unknown")
>         String name,
>         @ValueMapValue(name = "age") @Default(intValues = 0)
>         int age
> ) {}
> {code}
> The above issue should be addressed by introducing support for injection in records' implicit constructors.
> Note:
> 1. For records, only constructor injection is supported since records cannot have instance fields (code with such fields will not compile).
> 2. Apache Sling Models Implementation is currently based on Java 8 and may also be executed in a Java 8 environment. Therefore, the records check should be introduced via dynamic loading of the `java.lang.Record` class.



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