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MapStruct is not generating implementation classes

Posted by: admin December 28, 2021 Leave a comment

Questions:

I am using Mapstruct and Lombok with maven and IDEA and it is refusing to generate mappers implementation. Config:

<?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>
...

    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.0.5.RELEASE</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent>

    <properties>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
        <project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
        <maven.compiler.source>11</maven.compiler.source>
        <maven.compiler.target>11</maven.compiler.target>
        <java.version>11</java.version>
        <org.mapstruct.version>1.3.0.Beta2</org.mapstruct.version>
        <lombok.version>1.18.2</lombok.version>
    </properties>

    <dependencies>
        <!-- spring deps -->
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-actuator</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-jdbc</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
            <exclusions>
                <exclusion>
                    <groupId>org.springframework.boot</groupId>
                    <artifactId>spring-boot-starter-tomcat</artifactId>
                </exclusion>
            </exclusions>
        </dependency>
        ...

        <!-- lombok dep -->
        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
            <version>${lombok.version}</version>
        </dependency>

        <dependency>
            <groupId>org.mapstruct</groupId>
            <artifactId>mapstruct</artifactId>
            <version>${org.mapstruct.version}</version>
        </dependency>

    </dependencies>

    <build>
        <finalName>${project.artifactId}</finalName>
        <plugins>
            <plugin>
                <groupId>org.codehaus.mojo</groupId>
                <artifactId>build-helper-maven-plugin</artifactId>
                <executions>
                    <execution>
                        <id>add-source</id>
                        <phase>generate-sources</phase>
                        <goals>
                            <goal>add-source</goal>
                        </goals>
                        <configuration>
                            <sources>
                                <source>${project.build.directory}/generated-sources/java/</source>
                                <source>${project.build.directory}/generated-sources/annotations/</source>
                            </sources>
                        </configuration>
                    </execution>
                </executions>
            </plugin>
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-compiler-plugin</artifactId>
                <version>3.8.0</version>
                <configuration>
                    <release>11</release>
                    <annotationProcessorPaths>
                        <path>
                            <groupId>org.projectlombok</groupId>
                            <artifactId>lombok</artifactId>
                            <version>${lombok.version}</version>
                        </path>
                        <path>
                            <groupId>org.mapstruct</groupId>
                            <artifactId>mapstruct-processor</artifactId>
                            <version>${org.mapstruct.version}</version>
                        </path>
                    </annotationProcessorPaths>
                </configuration>
            </plugin>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
            </plugin>
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-jar-plugin</artifactId>
                <version>3.0.2</version>
                <configuration>
                    <archive>
                        <manifestEntries>
                            <Implementation-Version>${project.version}</Implementation-Version>
                        </manifestEntries>
                    </archive>
                </configuration>
            </plugin>
        </plugins>
    </build>

   ...
</project>

Both Mapstruct and Lombok are registered as annotations processors with idea:
enter image description here

Implementation files does not generate when I try to build with IDEA or if I try maven clean install.

I have tried changing Java from 11 to 8 and it still does not work. /target/generated-sources/annotations is just empty. Other project with same config is wroking fine.

Answers:

Adding mapstruct-processor dependency solved the issue for me.

###

If you use kotlin, you need to use kapt instead of annotationProcessor

Gradle example:

plugins {
  kotlin("kapt") version "1.4.32"
}
...
dependencies {
  ...
  implementation("org.mapstruct:mapstruct:1.4.2.Final")
  kapt("org.mapstruct:mapstruct-processor:1.4.2.Final")
}

Afterwards the implementation is generated if you execute gradle build

###

Problem was that my mappers were missing annotation @Mapper.

###

I have come across this issue. In my case gets this error:

Java: No implementation was created for Mapper due to having a problem in the erroneous element

when the app is running.

I used to spring boot version 2.4.3 when I decrease version to 2.2.6.RELEASE it start to work

###

For me the problem was:

<useIncrementalCompilation>false</useIncrementalCompilation>

After commented that out, all works!

<plugin>
    <artifactId>maven-compiler-plugin</artifactId>
    <version>3.8.1</version>
    <configuration>
        <source>${jdk.target.version}</source>
        <target>${jdk.target.version}</target>
        <!--<useIncrementalCompilation>false</useIncrementalCompilation>-->
        <annotationProcessorPaths>
            <path>
                <groupId>org.mapstruct</groupId>
                <artifactId>mapstruct-processor</artifactId>
                <version>${org.mapstruct.version}</version>
            </path>
        </annotationProcessorPaths>
    </configuration>
</plugin>

###

If you are using Kotlin with maven, you can add these dependencies:

    <dependency>
        <groupId>org.mapstruct</groupId>
        <artifactId>mapstruct</artifactId>
        <version>1.4.2.Final</version>
    </dependency>

    <dependency>
        <groupId>org.mapstruct</groupId>
        <artifactId>mapstruct-processor</artifactId>
        <version>1.4.2.Final</version>
    </dependency>

And add the kapt execution to the kotlin-maven-plugin as follows:

   <plugin>
                <groupId>org.jetbrains.kotlin</groupId>
                <artifactId>kotlin-maven-plugin</artifactId>
                <version>1.5.0</version>
                <executions>
                    <execution>
                        <id>kapt</id>
                        <goals>
                            <goal>kapt</goal>
                        </goals>
                        <configuration>
                            <sourceDirs>
                                <sourceDir>src/main/kotlin</sourceDir>
                                <sourceDir>src/main/java</sourceDir>
                            </sourceDirs>
                            <annotationProcessorPaths>
                                <!-- Specify your annotation processors here. -->
                                <annotationProcessorPath>
                                    <groupId>com.google.dagger</groupId>
                                    <artifactId>dagger-compiler</artifactId>
                                    <version>2.9</version>
                                </annotationProcessorPath>
                            </annotationProcessorPaths>
                        </configuration>
                    </execution>
                    <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>