Find JPA Entities without Field Access

The JPA specification allows field vs property based access for entities. Following query can be used to find entities using property access.

MATCH
  (entity:Jpa:Entity)-[:DECLARES]->(m:Method),
  (m)-[:ANNOTATED_BY]-()-[:OF_TYPE]->(a:Type)
WHERE
  a.fqn IN ["javax.persistence.Id", "javax.persistence.EmbeddedId"]
RETURN
  entity.name AS EntityWithPropertyAccess

JPA field based access is quite commonly used because of following reasons.

PROS:

• Only interesting fields are exposed to the outside world.
• The state is well encapsulated.
• You can declare getters and setters in interfaces, abstract classes or mapped superclasses, and override them in the concrete subclasses.
• It is easier to define transient contract; cleaner to mark fields transient than the getters.

CONS:

• No debugging possibility.

Reference:

http://www.oracle.com/technetwork/articles/marx-jpa-087268.html
http://www.adam-bien.com/roller/abien/entry/fieldvspropertybasedaccess

The above cypher query can easily be modelled as a constraint (i.e. jQAssistant rule):

<jqa:jqassistant-rules xmlns:jqa=
    "http://www.buschmais.com/jqassistant/core/analysis/rules/schema/v1.0">

    <constraint id="my-rules:EntitiesMustUseFieldAccess">
        <requiresConcept refId="jpa2:Entity" />
        <description>Verifies that entities prefer field access 
            over property access.</description>
        <cypher><![CDATA[
            MATCH
                (entity:Jpa:Entity)-[:DECLARES]->(m:Method),
                (m)-[:ANNOTATED_BY]-()-[:OF_TYPE]->(a:Type)
            WHERE 
                a.fqn IN
                  ["javax.persistence.Id", "javax.persistence.EmbeddedId"]
            RETURN
                entity.name AS EntityWithoutFieldAccess
        ]]></cypher>
    </constraint>

    <group id="default">
        <includeConstraint refId="my-rules:EntitiesMustUseFieldAccess" />
    </group>
</jqa:jqassistant-rules>