SlingModel still returning null when adapting item - aem

Question

I am trying to get Sling Models working.
I have a simple annotated POJO that maps to a JCR Node by convention as follows:
#Model(adaptables=Resource.class)
public class FlushRule {
#Inject
public String optingRegex;
}
I have set a String value in optingRegex.
When I try to use it:
FlushRule currentRule=rule.adaptTo(FlushRule.class);
Although the correct object is in rule, currentRule is null.
I looked in
http://localhost:4502/system/console/adapters
and couldn't find any adapters.
Any tips would be appreciated.

Answer 1

You need to add following lines to the maven-bundle-plugin configuration in your pom.xml:
<configuration>
<instructions>
<Sling-Model-Packages>
org.apache.sling.models.it.models
</Sling-Model-Packages>
</instructions>
</configuration>
where org.apache.sling.models.it.models is the Java package containing your models. The configured package (and all its subpackages) will be scanned for #Models. More information can be found on the Sling website.

Answer 2

Another reason why the Sling Model object could be null is when the Sling Model has a parameterised constructor and no default constructor.
Example:
#Model(adaptables = Resource.class)
public class CompetitionRound {
#Inject
String round;
public CompetitionRound(String round) {
this.round = round;
}
}
Add a default constructor and it should work.
#Model(adaptables = Resource.class)
public class CompetitionRound {
#Inject
String round;
public CompetitionRound() {
}
public CompetitionRound(String round) {
this.round = round;
}
}