Question

Spring Boot，Hibernate / JPA和MySQL。我有下表：

multResult

我希望此表能够将O / R映射到具有 CREATE TABLE IF NOT EXISTS fizzbuzzes ( fizzbuzz_id BIGINT UNSIGNED NOT NULL AUTO_INCREMENT, fizzbuzz_type_a VARCHAR(250) NOT NULL, fizzbuzz_type_b VARCHAR(250) NOT NULL, fizzbuzz_type_c VARCHAR(250) NOT NULL, fizzbuzz_type_d VARCHAR(250) NOT NULL, fizzbuzz_type_e VARCHAR(250) NOT NULL, fizzbuzz_type_f VARCHAR(250) NOT NULL, fizzbuzz_type_g VARCHAR(250) NOT NULL, fizzbuzz_type_h VARCHAR(250) NOT NULL, fizzbuzz_type_i VARCHAR(250) NOT NULL, fizzbuzz_type_j VARCHAR(250) NOT NULL, fizzbuzz_type_k VARCHAR(250) NOT NULL, fizzbuzz_type_l VARCHAR(250) NOT NULL, fizzbuzz_type_m VARCHAR(250) NOT NULL, fizzbuzz_type_n VARCHAR(250) NOT NULL, fizzbuzz_type_o VARCHAR(250) NOT NULL, fizzbuzz_type_p VARCHAR(250) NOT NULL, CONSTRAINT pk_fizzbuzzes PRIMARY KEY (fizzbuzz_id); ); 的JPA实体，该实体包含所有fizzbuzz类型A到P.

所以不是你通常会看到的：

Map<String,String>

...相反，我想：

@Entity
@Table(name = "fizzbuzzes")
public class Fizzbuzz {
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Long id;

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

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

    // ...

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

    // Getters, setters & ctors
}

@Entity @Table(name = "fizzbuzzes") public class Fizzbuzz { @Id @GeneratedValue(strategy = GenerationType.IDENTITY) private Long id; @Column(name = "???") private Map<String,String> types; // Getters, setters & ctors }的密钥可能是硬编码字符串types，typeA，...，typeB，typeP的值将是值来自DB表中的各个列。

这可能吗，如果是这样的话？

Answer 1

排序。如果您可以将类型值放在单独的表中，则可以。然后，您可以使用@ElmentCollection和@MapKeyColumn。

例如：

@ElementCollection
@MapKeyColumn(name="type_key")
@Column(name="type_value")
@CollectionTable(name="fizzbuzz_types", joinColumns=@JoinColumn(name="fizzbuzz_id"))
Map<String, String> types= new HashMap<>();

否则，需要为您的第一样品中有硬编码类型的列，并可以添加@PostLoad和@PrePersist钩从瞬态地图静态列转换为/

类似的东西：

@Entity
@Table(name = "fizzbuzzes")
public class Fizzbuzz {
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Long id;

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

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

    @Transient
    private Map<String, String> types = new HashMap<>();

    @PostLoad
    public void toMap() {
       this.types.put("typeA", this.typeA);
       this.types.put("typeB", this.typeB);
    }
    @PrePersist
    public void fromMap() {
       this.typeA = this.types.get("typeA");
       this.typeB= this.types.get("typeB");
    }
}

Hibernate / JPA映射列到Map类型

1 个答案: