Spring boot: Custom mapping between DTO and Entity using ModelMapper

Question

I would like to map my DTO (CreateOrUpdatePostRequest) to my entity Post.

But I'm not sure how to go about it since my entity has relationships like this:

@Entity
@Table(name = "POSTS")
@Data
public class Post {
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    @Column(name = "post_id")
    private int id;

    private String title;

    private String description;

    @Temporal(TemporalType.DATE)
    @Column(name = "expire_at")
    private Calendar expireAt;

    @ManyToOne
    @JoinColumn(name = "CATEGORY_ID")
    private Category category;

    @ManyToMany(fetch = FetchType.EAGER)
    @JoinTable(name = "TAG_POST", joinColumns = { 
            @JoinColumn(name = "post_id", nullable = false, updatable = false) }, 
            inverseJoinColumns = { @JoinColumn(name = "tag_id", 
                    nullable = false, updatable = false) })
    private Set<Tag> tags = new HashSet<Tag>(0);
}

A post can have one category and several tags.

And here is my DTO :

@Data
public class CreateOrUpdatePostRequest {
    @NotNull
    @Size(min = 10, max = 30)
    private Sting title;

    @NotNull
    @Size(min = 50, max = 600)
    private String description

    @NotNull
    @ValidDateString
    private String expireAt;

    @NotNull
    private Category category;

    @NotNull
    private List<TagDTO> tags;

    public List<Integer> getTagIds() {
        return this.getTags().stream().map(TagDTO::getId).collect(Collectors.toList());
    }
}

Problem: My problem is that I have to apply a particular mapping logic for some properties to make sure that the tags are valid for example:

post.setTags(tagService.findAllByIds(request.getTagIds()));

So I guess the mapping should be done in my PostService knowing that I have to access the tagService? What I mean is that I can't really create a toEntity method in my CreateOrUpdateRequest.
Is there a way to leave the default ModelMapper behavior for all properties, but specify specific behavior using an external service for certain properties?
How to proceed if for example my DTO has a DTO inside that needs the same behavior described above, for example in a TagDTO?

Just create class/service which will convert your dto to entity or add a function inside entity which can create this entity based on DTO (maybe something like builder class or something) — Morph21
– Morph21, Commented Nov 17, 2021 at 13:57

Hardik Uchdadiya · Accepted Answer · 2021-11-17 13:58:49Z

4

I am not sure whether you have already gone through MapStruct thing, but you can look at it here in detail.

https://medium.com/uphill-engineering-design/deep-dive-into-mapstruct-spring-7ddd8dac3d6d

answered Nov 17, 2021 at 13:58

Hardik Uchdadiya

3781 silver badge9 bronze badges

Sign up to request clarification or add additional context in comments.

9 Comments

Jedupont Over a year ago

I have to study all this knowing that I am doing this on a very large entity. Where do you store your mappers in your code? I'm talking about code organization. In a new Mapper package ?

Hardik Uchdadiya Over a year ago

yes, they can have their own package

Jedupont Over a year ago

Ok thanks. If I understand correctly MapStruct relies on interfaces to generate the class that will convert my DTO into an entity. So I can hardly have a specific behavior like my example with services?

Hardik Uchdadiya Over a year ago

yes, but you can override the behavior whichever way you want, you will find it in the article I shared

Jedupont Over a year ago

Yes, I saw the link. But can I for example use the same MapStruct for adding an entity for example and the same but ignoring null properties for updating an entity for example. I'm trying to do a CRUD.

|

João Dias · Accepted Answer · 2021-11-17 23:37:03Z

0

This is borderline opinion-based, but still here is my take on this:

I guess that your PostService is a Spring-managed Bean (possibly annotated with @Service), so I would say the mapping should be done there, using TagService to get the Tags.
I am not a big fan of any mapper library, simply because once using Spring you have already enough magic going around in your code. Having said that, I much more prefer to be explicit and map the models on my own. You have full flexibility while doing so.
I would say that TagDto should be mapped by the TagService.

answered Nov 17, 2021 at 23:37

João Dias

17.7k6 gold badges39 silver badges47 bronze badges

Collectives™ on Stack Overflow

Spring boot: Custom mapping between DTO and Entity using ModelMapper

2 Answers 2

9 Comments

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

9 Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Related