CQ5 QueryBuilder Reference in Sling Servlet - aem

Question

I am declaring a sling servlet like so
#Component(metatype = false)
#Service(Servlet.class)
#Properties({
#Property(name = "sling.servlet.paths", value = "/bin/foo/bar"),
#Property(name = "sling.servlet.methods", value = "POST") })
public class FooBarServlet extends SlingAllMethodsServlet {
...
}
I override doPost like so
#Override
protected void doPost(SlingHttpServletRequest request, SlingHttpServletResponse response) throws IOException {
...
}
And I am able to post from a client. Great!
I throw in the following
#Reference
private QueryBuilder queryBuilder;
as per the documentation, a reference to query builder should be injected. But it does not seem to. In the log I see this error
bindQueryBuilder cannot be found (java.lang.VerifyError: ...
And when I try to post to the servlet I get this
javax.jcr.RepositoryException: org.apache.sling.api.resource.PersistenceException: Resource at '/bin/foo/bar' is not modifiable.
And in the OSGi console I see my bundle is installed, and this is what it has to say about my servlet
Service ID 3075 Types: javax.servlet.Servlet
Service PID: com.myproject.FooBarServlet
Component Name: com.myproject.FooBarServlet
Component ID: 5526
Vendor: Adobe
Any suggestions as to what I am doing wrong?

Answer 1

I had been using this tutorial as a reference.
I came across this about the Felix Service Component Runtime (SCR)
and so I implemented the following
protected void activate(ComponentContext context) {
LOGGER.info("activating {}", this.getClass().getName());
}
protected void unbindQueryBuilder(QueryBuilder queryBuilder) {
this.queryBuilder = null;
}
protected void bindQueryBuilder(QueryBuilder queryBuilder) {
this.queryBuilder = queryBuilder;
}
and it worked! So upon closer investigation I learned that these bind/unbind methods are actually supposed to be generated by the maven-scr-plugin, of which I have version 1.6.0
<plugin>
<groupId>org.apache.felix</groupId>
<artifactId>maven-scr-plugin</artifactId>
<version>1.6.0</version>
<executions>
<execution>
<id>generate-scr-scrdescriptor</id>
<goals>
<goal>scr</goal>
</goals>
<configuration>
<!-- Private service properties for all services. -->
<properties>
<service.vendor>Adobe</service.vendor>
</properties>
</configuration>
</execution>
</executions>
<dependencies>
<dependency>
<groupId>org.slf4j</groupId>
<artifactId>slf4j-simple</artifactId>
<version>1.5.2</version>
</dependency>
</dependencies>
</plugin>
and for the annotations I have 1.4.0
<dependency>
<groupId>org.apache.felix</groupId>
<artifactId>org.apache.felix.scr.annotations</artifactId>
<version>1.4.0</version>
<scope>provided</scope>
</dependency>
so although I am not sure why the bind/unbind methods are not getting generated, I know that they should be, so I generate them manually.
Update
I tried to update the maven-scr-plugin to version 1.20.0, which yielded the following error during mvn build
[ERROR] Project depends on org.apache.felix:org.apache.felix.scr.annotations:jar:1.4.0:provided
[ERROR] Minimum required version is 1.9.0
so... I updated the org.apache.felix.scr.annotations to 1.9.0. And it works! My bind/unbind accessors are generated and all is great. However, I am concerned and do not know if I should use version 1.9.0 of org.apache.felix.scr.annotations because I am marking it as provided in the maven dependency and when I look at the OSGi bundles installed on the cq instance I see the following
Apache Felix Declarative Services (org.apache.felix.scr) : Version 1.6.3.R1409029

Answer 2

For the dependency injection to work, you should declare the member variable as public.
Try changing it to
#Reference
public QueryBuilder queryBuilder;