no default constructor for JPA entity with Kotlin

Question

I have read that you need the kotlin-maven-noarg compiler plugin for entity classes in order for it to generate default-parameter less cosntructor.

But the application does not start with the following error:

No default constructor for entity

Can you tell me what am I doing wrong?

pom.xml:

    <?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>
    {...}
    <build>
        <sourceDirectory>src/main/java</sourceDirectory>
        <resources>
            <resource>
                <directory>src/main/resources</directory>
            </resource>
        </resources>

        <testSourceDirectory>src/test/java</testSourceDirectory>
        <testResources>
            <testResource>
                <directory>src/test/resources</directory>
            </testResource>
        </testResources>
        <plugins>
            <plugin>
                <artifactId>maven-compiler-plugin</artifactId>
                <version>3.1</version>
                <configuration>
                    <source>1.8</source>
                    <target>1.8</target>
                </configuration>
            </plugin>
            <plugin>
                <groupId>org.jetbrains.kotlin</groupId>
                <artifactId>kotlin-maven-plugin</artifactId>
                <version>${kotlin.version}</version>
                <executions>
                    <execution>
                        <id>compile</id>
                        <phase>compile</phase>
                        <goals>
                            <goal>compile</goal>
                        </goals>
                    </execution>
                    <execution>
                        <id>test-compile</id>
                        <phase>test-compile</phase>
                        <goals>
                            <goal>test-compile</goal>
                        </goals>
                    </execution>
                </executions>
            </plugin>
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-compiler-plugin</artifactId>
                <executions>
                    <execution>
                        <id>compile</id>
                        <phase>compile</phase>
                        <goals>
                            <goal>compile</goal>
                        </goals>
                    </execution>
                    <execution>
                        <id>testCompile</id>
                        <phase>test-compile</phase>
                        <goals>
                            <goal>testCompile</goal>
                        </goals>
                    </execution>
                </executions>
            </plugin>
            <plugin>
                <artifactId>kotlin-maven-plugin</artifactId>
                <groupId>org.jetbrains.kotlin</groupId>
                <version>${kotlin.version}</version>

                <configuration>
                    <compilerPlugins>
                        <plugin>jpa</plugin>
                    </compilerPlugins>

                    <pluginOptions>
                        <option>jpa:annotation=javax.persistence.Entity</option>
                    </pluginOptions>
                </configuration>

                <dependencies>
                    <dependency>
                        <groupId>org.jetbrains.kotlin</groupId>
                        <artifactId>kotlin-maven-noarg</artifactId>
                        <version>${kotlin.version}</version>
                    </dependency>
                </dependencies>
            </plugin>

        </plugins>
    </build>

    <properties>
        {...}
        <junit.version>4.12</junit.version>
        <kotlin.version>1.1.0</kotlin.version>
    </properties>

        {...}

        <dependency>
            <groupId>org.jetbrains.kotlin</groupId>
            <artifactId>kotlin-stdlib</artifactId>
            <version>${kotlin.version}</version>
        </dependency>
        <dependency>
            <groupId>org.jetbrains.kotlin</groupId>
            <artifactId>kotlin-test</artifactId>
            <version>${kotlin.version}</version>
            <scope>test</scope>
        </dependency>
        <dependency>
            <groupId>org.jetbrains.kotlin</groupId>
            <artifactId>kotlin-reflect</artifactId>
            <version>${kotlin.version}</version>
        </dependency>

    </dependencies>

</project>

test class:

@RunWith(SpringJUnit4ClassRunner::class)
@ContextConfiguration(classes = arrayOf(VedicaConfig::class))
class InitStructures {
    private var vedicaDBInit: VedicaDBInit? = null

    @Before
    fun init() {
        vedicaDBInit = VedicaDBInit()
    }

    @Test
    fun initClientFolders() {
    }
}

I'm using Intellij IDEA with Kotlin 1.1.0, so for deployment I just click debug/run with Tomcat run configuration selected and for running test I just right click on the test class and also click run/debug.

Answer 1

Have you tried running your Maven compile goal before running your test? I've found that Intellij's default configurations for Kotlin run/test don't fire Maven plugins and therefore don't apply the no-arg plugin.

Try running your compile goal and then running your test again.

Answer 2

Finally after a few attempts found how to fix it:

• Open Run/Debug Configurations window (Run > Edit Configurations)
• Select your existing Spring boot run configuration

• Add the following presets in Program arguments field:

  -Xplugin=$KOTLIN_HOME/lib/noarg-compiler-plugin.jar -P plugin:org.jetbrains.kotlin.noarg:preset=jpa

• Click ok to save configuration
• Stop and Run project again

Useful link: No-arg compiler plugin info

Answer 3

I had similar issue with intellij/gradle/kotlin.

In my case I always started the webapplication by calling the main method through intellij editor Run-Icon. I don't know what excatly is going wrong but somehow the build process wasn't finished correctly.

In contrast, If I started the webapplication from console by calling ./gradlew bootRun everything worked fine!

Answer 4

I had the same problem. I was using gradle build btw.

What worked for me was, Instead of running default run config that intellij provides I created a new run config of type gradle

On the Gradle project selected my project and on Tasks selected bootRun

And then ran my project and it worked for me

Answer 5

This was an Intellij bug and has been fixed in the following versions:

• IDEA 171.2455 + Kotlin plugin 1.1.0-dev-6111.
• IDEA 171.2272.14 (EAP) + Kotlin plugin 1.1.0-beta-17.

Details here: https://youtrack.jetbrains.com/issue/KT-15686