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new def3c670c SLING-3716 Clarify constructor injection (#112)
def3c670c is described below
commit def3c670cc43a80c566af735664bce4e85d1b381
Author: Konrad Windszus <[email protected]>
AuthorDate: Sat Jul 8 14:42:40 2023 +0200
SLING-3716 Clarify constructor injection (#112)
Document injection specific annotations. Clarify that @Inject on
constructor is mandatory.
Add chapters for field, method and constructor injection
---
.../jbake/content/documentation/bundles/models.md | 20 ++++++++++++++------
1 file changed, 14 insertions(+), 6 deletions(-)
diff --git a/src/main/jbake/content/documentation/bundles/models.md
b/src/main/jbake/content/documentation/bundles/models.md
index 073718b8b..6837162a7 100644
--- a/src/main/jbake/content/documentation/bundles/models.md
+++ b/src/main/jbake/content/documentation/bundles/models.md
@@ -12,7 +12,11 @@ Sling Models provide an easy way to achieve this,
integrating into the already e
# Basic Usage
## Model Classes
-In the simplest case, the model class is annotated with `@Model` and the
adaptable class. Fields which need to be injected are annotated with
`@ValueMapValue`:
+In the simplest case, the model class is annotated with `@Model` and the
adaptable class.
+
+### Field Injection
+
+Fields which need to be injected are annotated with `@ValueMapValue`:
::java
import org.apache.sling.api.resource.Resource;
@@ -57,7 +61,8 @@ In this case, a property named `propertyName` will be looked
up from the Resourc
String packagePrivateField;
}
-
+### Method Injection (on interface only models)
+
For an interface, it is similar:
::java
@@ -70,22 +75,25 @@ For an interface, it is similar:
Interface methods must be `public`. Even though private interface methods have
been available since Java 9, Sling Models uses Dynamic Proxies to instantiate
the interfaces, which does not work with private interface methods.
Additionally, while default interface methods will work with interface
injection, the default implementation (in the interface) is currently not used,
and will not be executed.
-Constructor injection is also supported (as of Sling Models 1.1.0):
+### Constructor Injection
+
+Constructor injection is also supported (as of [Sling Models
1.1.0](https://issues.apache.org/jira/browse/SLING-3716)):
::java
@Model(adaptables=Resource.class)
public class MyModel {
@Inject
- public MyModel(@Named("propertyName") String propertyName) {
+ public MyModel(@ValueMapValue(name="propertyName") String
propertyName) {
// constructor code
}
}
-Because the name of a constructor argument parameter cannot be detected via
the Java Reflection API a `@Named` annotation is mandatory for injectors that
require a name for resolving the injection.
+Because the name of a constructor argument parameter cannot be detected via
the Java Reflection API a `@Named` annotation (or a `name` element on injector
specific annotations) is mandatory for injectors that require a name for
resolving the injection.
+In order for a constructor to be used for injection *it has to be annotated on
method level with `@Inject`*. In addition using injector-specific annotations
on parameter level is supported.
Constructors may use any visibility modifier (as of [Sling Models
1.5.0](https://issues.apache.org/jira/browse/SLING-8069)).
-## @Model and adaptable types
+## @Model and Adaptable Types
When defining a Sling Model class, the `adaptables` parameter to the `@Model`
annotation is mostly determined by the injectors being used. The provided class
must satisfy the needs of all injectors (for the details see [the table
below](#available-injectors-1)). For example if the model class only uses the
`ValueMap` injector, the adaptables parameter can be a `Resource`, a
`SlingHttpServletRequest` or both. But if the `Request Attribute` injector is
used, only an adaptable of the type ` [...]
