使用MapStruct进行Dto到实体的转换会产生错误

Question

I am trying to create a mapper of "PersonDto" class to "PersonEntity" using MapStruct

Please consider the following Entity, Dto and Mapper classes.

PersonEntity.java

package com.example.car;

import java.util.ArrayList;
import java.util.List;

public class PersonEntity {
    private String name;
    private List<CarEntity> cars;

    public PersonEntity() {
        cars = new ArrayList<>();
    }

    public boolean addCar(CarEntity carEntitiy) {
        return cars.add(carEntitiy);
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public List<CarEntity> getCars() {
        return cars;
    }

    public void setCars(List<CarEntity> carEntities) {
        this.cars = carEntities;
    }
}

CarEntity.java

package com.example.car;

public class CarEntity {
    private String model;

    public String getModel() {
        return model;
    }

    public void setModel(String model) {
        this.model = model;
    }
}

PersonDto.java

package com.example.car;

import java.util.ArrayList;
import java.util.List;

public class PersonDto {
    private String name;
    private List<CarDto> cars;

    public PersonDto() {
        cars = new ArrayList<>();
    }

    public boolean addCar(CarDto carDto) {
        return cars.add(carDto);
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public List<CarDto> getCars() {
        return cars;
    }

    public void setCars(List<CarDto> carDtos) {
        this.cars = carDtos;
    }
}

CarDto.java

package com.example.car;

public class CarDto {
    private String model;

    public String getModel() {
        return model;
    }

    public void setModel(String model) {
        this.model = model;
    }
}

PersonMapper

package com.example.car;

import org.mapstruct.CollectionMappingStrategy;
import org.mapstruct.Mapper;
import org.mapstruct.factory.Mappers;

@Mapper(collectionMappingStrategy = CollectionMappingStrategy.ADDER_PREFERRED)
public interface PersonMapper {

    PersonMapper INSTANCE = Mappers.getMapper(PersonMapper.class);

    PersonEntity personDtoToPersonEntity(PersonDto personDto);
}

When I am trying to generate code using the maven instructions provided at this link I am receiving the following error:

Can't map property "java.util.List cars" to "com.example.car.CarEntity cars". Consider to declare/implement a mapping method: "com.example.car.CarEntity map(java.util.List value)".

If i remove the "adder" method from Person classes it works fine. But I really want to use adder methods (for JPA entities parent child relationship purpose).

I am not sure why MapStruct not interpreting the cars property in PersonEntity as List. It is interpreting that property as a simple CarEntity and not the List of CarEntity.

Answer 1

You should consider mapping the "Has-A" property of your class too
Just include CarEntity carDtoToCarEntity(CarDto carDto)
Here is code snippet:

 @Mapper(collectionMappingStrategy = CollectionMappingStrategy.ADDER_PREFERRED) public interface PersonMapper { PersonMapper INSTANCE = Mappers.getMapper(PersonMapper.class); CarEntity carDtoToCarEntity(CarDto carDto); PersonEntity personDtoToPersonEntity(PersonDto personDto); } 

Let me know if you are still stuck.

Answer 2

In your @Mapper

@Mapper(componentModel = "spring",uses = CarMapper.class) 

annotation you should use mapper for any kind of nested type you have in your entity