Relationships

Squizy supports standard JPA relationship annotations and automatically generates the appropriate UI components for managing related entities.

UI Rendering Summary

The UI component used for a relationship depends on the relationship type and ownership (cascade configuration):

Relationship	Owned (cascade ALL)	Reference (no cascade)
@ManyToOne	—	Dropdown / select
@OneToOne	Inline form (embedded)	Dropdown / select
@OneToMany	Inline table	—
@ManyToMany	—	Multi-select (chips)
@ElementCollection	Inline list	—

Owned relationships (cascade = CascadeType.ALL, orphanRemoval = true) allow creating and editing child records directly from the parent form. Reference relationships link to independently managed entities via selection components.

Supported Relationships

@ManyToOne

Renders as a dropdown/select in the UI:

@Entity
@SquizyEntity
public class Product {

    @ManyToOne(optional = false)
    @NotNull
    private Category category;
}

@OneToOne

Renders as a dropdown or inline form depending on cascade configuration:

@Entity
@SquizyEntity
public class Order {

    @OneToOne(optional = false, cascade = CascadeType.ALL, orphanRemoval = true)
    @NotNull
    private Address address;
}

@OneToMany

Renders as a multi-select or inline table:

@Entity
@SquizyEntity
public class Order {

    @OneToMany(cascade = CascadeType.ALL, orphanRemoval = true)
    @NotEmpty
    private List<OrderLine> products;
}

@ManyToMany

Renders as a multi-select component:

@Entity
@SquizyEntity
public class City {

    @ManyToMany(fetch = FetchType.EAGER)
    private Set<City> closeCities;
}

@ElementCollection

Supported for both simple types and enums:

@ElementCollection
private List<String> aliases;

@ElementCollection(targetClass = Badge.class)
@CollectionTable
@Enumerated(EnumType.STRING)
private List<Badge> badges;

Cascade Operations

Owned Entities (cascade all)

When a child entity's lifecycle is fully managed by the parent:

@OneToOne(cascade = CascadeType.ALL, orphanRemoval = true)
private Address address;

@OneToMany(cascade = CascadeType.ALL, orphanRemoval = true)
private List<OrderLine> products;

With orphanRemoval = true, removing a child from the collection deletes the orphaned record.

Reference Entities (no cascade)

When a child entity has its own independent lifecycle:

@ManyToOne(optional = false)
@NotNull
private Category category;

Bidirectional Relationships

For bidirectional relationships, use mappedBy on the non-owning side:

@Entity
@SquizyEntity
public class Owner {

    @OneToMany(cascade = CascadeType.ALL, mappedBy = "owner", orphanRemoval = true)
    private List<Book> books;
}

@Entity
@SquizyEntity
public class Book {

    @ManyToOne
    @JsonBackReference
    private Owner owner;
}

Use @JsonManagedReference / @JsonBackReference or @JsonIgnoreProperties to avoid circular serialization issues.