Query DSL Q type classes not generated

Question

I am trying to use QueryDSL in my eclipse maven project. These are the dependencies.

<properties>
        <!-- The main class to start by executing java -jar -->
        <start-class>my.app.market.DBApp</start-class>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
        <maven.compiler.source>1.8</maven.compiler.source>
        <maven.compiler.target>1.8</maven.compiler.target>
        <querydsl.version>4.1.4</querydsl.version>
        <apt-maven-plugin.version>1.1.3</apt-maven-plugin.version>

</properties>

<dependency>
            <groupId>com.querydsl</groupId>
            <artifactId>querydsl-apt</artifactId>
            <version>4.1.4</version>
            <scope>provided</scope>
        </dependency>
        <dependency>
            <groupId>com.querydsl</groupId>
            <artifactId>querydsl-jpa</artifactId>
            <version>4.1.4</version>
        </dependency>
        <dependency>
            <groupId>org.slf4j</groupId>
            <artifactId>slf4j-log4j12</artifactId>
            <version>1.6.1</version>
        </dependency>

<build>
        <plugins>
            <plugin>
                <groupId>com.mysema.maven</groupId>
                <artifactId>apt-maven-plugin</artifactId>
                <version>1.1.3</version>
                <executions>
                    <execution>
                        <goals>
                            <goal>process</goal>
                        </goals>
                        <configuration>
                            <outputDirectory>target/generated-sources</outputDirectory>
                            <processor>com.querydsl.apt.jpa.JPAAnnotationProcessor</processor>
                        </configuration>
                    </execution>
                </executions>
            </plugin>
        </plugins>
    </build>

After this I try to write the queries.

@Repository
public class QueryDSLRepo {

    @PersistenceContext
    private EntityManager em;

    public ReportingParamDAO save(final ReportingParamDAO reportingParamDAO) {
        em.persist(reportingParamDAO);
        return reportingParamDAO;
    }

    public List<ReportingParamDAO> findreportingParamDAOsByIdQueryDSL(final Integer id) {
        final JPAQuery<ReportingParamDAO> query = new JPAQuery<>(em);
        final QReportingParamDAO reportingParamDAO = QReportingParamDAO.reportingParamDAO;

        return query.from(reportingParamDAO).where(reportingParamDAO.id.eq(id)).fetch();
    }


}

But I get the error

QReportingParamDAO cannot be resolved to a type

Note: ReportingParamDAO is an entity class.

This means that the Q type class for my DAO is not generated. I am not sure why it wasn't generated. Do I need to do something else? I came across this post but the user is working on IntelliJ and I can't seem to make it work in my case. Can someone please help me. Thanks !!

Answer 1

I have tested with your pom.xml. The Q classes were generated for me but I couldn't access them from my source code. The problem is that the generated-sources is not on classpath by default. Add that on the classpath and you will be able to use them in your source code.

1. Check the target/generated-sources directory to see if the classes are actually there. (You should be able to find them because I tested with your pom.xml)
2. If you add target/generated-sources to classpath, you application will work. But I don't think that is a good idea. Because all the files in the classpath will be indexed by the IDE and your IDE will be slower. All the files in the generated-sources folder need not be indexed. So add target/generated-sources/java to classpath and change your query-dsl plugin to generated Q class to target/generated-sources/java

Answer 2

I recently have the same issue has you.

It seems apt-maven-plugin doesn't like empty .java file. If you have one in your project he will not generate any class without indication about the empty file, which can be very hard to find.