@MAPSTRUCT. No property named "packaging" exists in source parameter(s)

I am writing an MVC REST application with Spring Boot and Hibernate. I decided to do DTO mapping using MAPSTRUCT. It seems that I did everything according to the guide, but an error is issued. What is the problem, I cannot understand. There is very little information on forums and on google.

P.S. At first I thought that the problem was in Lombok, so I removed Lombok and manually assigned getters / setters. Then the problem was not solved. I took both in the Drink class and in the DrinkDTO I prescribed getters / setters. It still didn't help.

Drink:

@Entity
@Table(name = "drink", schema = "public")
public class Drink {

    public Drink() { // Constructor for Hibernate

    }


    // Fields
    //
    private @Id
    @GeneratedValue
    Long id;

    @Column(name = "name")
    private String name;

    @Column(name = "price")
    private float price;

    @Column(name = "about")
    private String about;

    @Column(name = "is_deleted")
    private boolean isDeleted;

    // Relationships
    //
    @ManyToOne
    @JoinColumn(name = "packaging_id")
    private Packaging packaging;

    @ManyToOne
    @JoinColumn(name = "manufacturer_id")
    private Manufacturer manufacturer;

    @ManyToOne
    @JoinColumn(name = "country_id")
    private Countries countries;
}

DrinkDTO:

public class DrinkDTO {

    // Fields
    //
    private String drinkName;

    private float drinkPrice;

    private String drinkAbout;

    private Packaging drinkPackaging;

    private Manufacturer drinkManufacturer;

    private Countries drinkCountries;


    // Getters and Setters
    //
    public String getDrinkName() {
        return drinkName;
    }

    public void setDrinkName(String drinkName) {
        this.drinkName = drinkName;
    }

    public float getDrinkPrice() {
        return drinkPrice;
    }

    public void setDrinkPrice(float drinkPrice) {
        this.drinkPrice = drinkPrice;
    }

    public String getDrinkAbout() {
        return drinkAbout;
    }

    public void setDrinkAbout(String drinkAbout) {
        this.drinkAbout = drinkAbout;
    }

    public Packaging getDrinkPackaging() {
        return drinkPackaging;
    }

    public void setDrinkPackaging(Packaging drinkPackaging) {
        this.drinkPackaging = drinkPackaging;
    }

    public Manufacturer getDrinkManufacturer() {
        return drinkManufacturer;
    }

    public void setDrinkManufacturer(Manufacturer drinkManufacturer) {
        this.drinkManufacturer = drinkManufacturer;
    }

    public Countries getDrinkCountries() {
        return drinkCountries;
    }

    public void setDrinkCountries(Countries drinkCountries) {
        this.drinkCountries = drinkCountries;
    }

    // toSTRING
    @Override
    public String toString() {
        return "DrinkDTO{" +
                "drinkName='" + drinkName + '\'' +
                ", drinkPrice=" + drinkPrice +
                ", drinkAbout='" + drinkAbout + '\'' +
                ", drinkPackaging=" + drinkPackaging +
                ", drinkManufacturer=" + drinkManufacturer +
                ", drinkCountries=" + drinkCountries +
                '}';
    }

CustomerController:

@GetMapping("/drinks")
    List<DrinkDTO> getAllDrinks(){
        return DrinkMapper.INSTANCE.drinksToDrinksDTO(customerService.getAllDrinks());
    }

BUILD.GRADLE

// Mapstruct
    implementation 'org.mapstruct:mapstruct:1.3.1.Final'
    annotationProcessor 'org.mapstruct:mapstruct-processor:1.3.1.Final'

DrinkMapper:

@Mapper
public interface DrinkMapper {

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

    @Mapping(source = "name", target = "drinkName")
    @Mapping(source = "price", target = "drinkPrice")
    @Mapping(source = "about", target = "drinkAbout")
    @Mapping(source = "packaging", target = "drinkPackaging")
    @Mapping(source = "manufacturer", target = "drinkManufacturer")
    @Mapping(source = "countries", target = "drinkCountries")
    DrinkDTO drinkToDrinkDTO(Drink drink);

    @Mapping(source = "drinkName", target = "name")
    @Mapping(source = "drinkPrice", target = "price")
    @Mapping(source = "drinkAbout", target = "about")
    @Mapping(source = "drinkPackaging", target = "packaging")
    @Mapping(source = "manufacturer", target = "drinkManufacturer")
    @Mapping(source = "countries", target = "drinkCountries")
    Drink drinkDTOtoDrink(DrinkDTO drinkDTO);

    @Mapping(source = "name", target = "drinkName")
    @Mapping(source = "price", target = "drinkPrice")
    @Mapping(source = "about", target = "drinkAbout")
    @Mapping(source = "packaging", target = "drinkPackaging")
    @Mapping(source = "manufacturer", target = "drinkManufacturer")
    @Mapping(source = "countries", target = "drinkCountries")
    List<DrinkDTO> drinksToDrinksDTO(List<Drink> drinks);
}

ERRORS:

The error comes from the fact that you tried to map properties from List<> objects, but those don't exist. Mapstruct is smart enough to generate mappers between lists, provided it knows how to map the elements inside the list.

So you don't need to specify @Mapping annotations on the list-to-list mapping. Mapstruct will use the drinkToDrinkDTO mapping method automatically.

@Mapping(...)
DrinkDTO drinkToDrinkDTO(Drink drink);

List<DrinkDTO> drinksToDrinksDTO(List<Drink> drinks);