如何创建两个实体并将它们关联起来

Question

首先，为您可能犯的语法错误道歉。 我的英文不是很好。

我正在尝试创建一个实体并与其他实体建立关系。

这个想法是发送一个 json 文件并获取一些属性来创建该实体，然后将该实体与另一个相关联。 但是，我不能因为抛出异常，例如：

试图从空一对一属性分配 id

因此，在我的 SchemeService 中，我尝试创建两个实体：

protected Scheme createScheme(final String creatorId, final String name, final String description, final InputStream inputStream) { 

    DeserializeJSONFile desJsonFile = new DeserializeJSONFile();
    desJsonFile.init(inputStream);

    TableEntity table = new TableEntity();
    table.setCreator(creatorId);
    table.setProperties(desJsonFile.getProperties().toString());
    table.setGeometry(desJsonFile.getGeometry().toString());
    createTable(table);

    Scheme scheme = new Scheme();
    scheme.setCreator(creatorId);
    scheme.setName(name);
    scheme.setDescription(description);
    scheme.setTable(table);
    createScheme(scheme);
    return scheme;
}

private void createTable(final TableEntity table) {
    tableDao.create(table);
}

protected void createScheme(final Scheme scheme) {
    schemeDao.create(scheme);
}

这是我的 TableEntity：

public class TableEntity extends BaseEntityActivable implements Serializable {

    private static final long serialVersionUID = 1L;

    @Id
    @GeneratedValue(strategy = GenerationType.SEQUENCE, generator = "SCHEME_SEQ_GEN")
    @SequenceGenerator(name = "SCHEME_SEQ_GEN", sequenceName = "test_seq_table", allocationSize = 1)
    @Column(name = "table_id")
    private Long tableId;

    @Type(type= "jsonb")
    @Column(name = "properties", columnDefinition = "json")
    private String properties;

    @Type(type= "jsonb")
    @Column(name = "geometry", columnDefinition = "json")
    private String geometry;

    @OneToOne
    @MapsId
    private Scheme scheme;
}

这是我的 SchemeEntity：

public class Scheme extends BaseEntityActivable implements Serializable {

    private static final long serialVersionUID = 1L;

    @Id
    @GeneratedValue(strategy = GenerationType.SEQUENCE, generator = "SCHEME_SEQ_GEN")
    @SequenceGenerator(name = "SCHEME_SEQ_GEN", sequenceName = "test_seq_scheme", allocationSize = 1)
    @Column(name = "scheme_id")
    private Long schemeId;

    @Column(name = "name", nullable = false)
    @NotEmpty(message = AxisMapsErrorConstants.NAME_CANT_BE_EMPTY)
    private String name;

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

    @OneToOne(mappedBy = "scheme", cascade = CascadeType.ALL)
    @JoinColumn(name = "scheme_id", referencedColumnName = "table_id", foreignKey = @ForeignKey(name = "fk_scheme_table_1"))
    private TableEntity table;

}

这是我的sql：

create sequence test_seq_table start 1 increment 1;
create sequence test_seq_scheme start 1 increment 1;

create table maps_table (
    table_id int8 not null,
    created_at timestamp not null,
    created_by varchar(255),
    updated_at timestamp,
    updated_by varchar(255),
    is_active boolean not null,
    properties jsonb not null,
    geometry jsonb not null,
    primary key (table_id)
);


create table maps_scheme (
    scheme_id int8 not null,
    created_at timestamp not null,
    created_by varchar(255),
    updated_at timestamp,
    updated_by varchar(255),
    is_active boolean not null,
    description varchar(255),
    name varchar(255) not null,
    table_id int8 not null,
    primary key (scheme_id)
);

    alter table maps_scheme 
       add constraint fk_scheme_table_1 
       foreign key (scheme_id) 
       references maps_table;

Answer 1

由于您使用的是 @mapsId，这意味着您在与方案的关系中使用相同的标识符，这意味着首先方案不应为空，并且每次刷新对象时它都应作为托管实体可用，这也意味着您可以仅从关系的一侧进行持久化，因为在持久化实体时方案的 id 应该可用。

我不确定您是否真的需要 @mapsId ，因为您已经有了双向关系，这意味着无论如何您都可以访问实体的两侧。

我建议在这里删除@mapsId。

Answer 2

谢谢大家帮助我。

这是我的解决方案。

方案：

public class Scheme extends BaseEntityActivable implements Serializable {

    private static final long serialVersionUID = 1L;

    @Id
    @GeneratedValue(strategy = GenerationType.SEQUENCE, generator = "SCHEME_SEQ_GEN")
    @SequenceGenerator(name = "SCHEME_SEQ_GEN", sequenceName = "aguas_seq_scheme", allocationSize = 1)
    @Column(name = "scheme_id")
    private Long schemeId;

    @Column(name = "name", nullable = false)
    @NotEmpty(message = AxisMapsErrorConstants.NAME_CANT_BE_EMPTY)
    private String name;

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

    @OneToOne(cascade= { CascadeType.ALL }, fetch = FetchType.LAZY)
    @JoinColumn(name="table_id")
    private TableEntity table;

}

表实体：

public class TableEntity extends BaseEntityActivable implements Serializable {

    private static final long serialVersionUID = 1L;

    @Id
    @GeneratedValue(strategy = GenerationType.SEQUENCE, generator = "SCHEME_SEQ_GEN")
    @SequenceGenerator(name = "SCHEME_SEQ_GEN", sequenceName = "aguas_seq_table", allocationSize = 1)
    @Column(name = "table_id")
    private Long tableId;


    @Type(type= "jsonb")
    @Column(name = "properties", columnDefinition = "json")
    private String properties;

    @Type(type= "jsonb")
    @Column(name = "geometry", columnDefinition = "json")
    private String geometry;

    @OneToOne(mappedBy= "table")
    private Scheme scheme;
}

查询语句：

create sequence aguas_seq_table start 1 increment 1;
create sequence aguas_seq_scheme start 1 increment 1;

create table maps_table (
    table_id int8 not null,
    created_at timestamp not null,
    created_by varchar(255),
    updated_at timestamp,
    updated_by varchar(255),
    is_active boolean not null,
    properties jsonb not null,
    geometry jsonb not null,
    primary key (table_id)
);


create table maps_scheme (
    scheme_id int8 not null,
    created_at timestamp not null,
    created_by varchar(255),
    updated_at timestamp,
    updated_by varchar(255),
    is_active boolean not null,
    description varchar(255),
    name varchar(255) not null,
    table_id int8 not null,
    primary key (scheme_id)
);

SchemeService 创建方案和表：

protected Scheme createScheme(final String creatorId, final String name, final String description, final InputStream inputStream) { 

    DeserializeJSONFile desJsonFile = new DeserializeJSONFile();
    desJsonFile.init(inputStream);

    TableEntity table = new TableEntity();
    table.setCreator(creatorId);
    table.setGeometry(desJsonFile.loadGeometries().toString());
    table.setProperties(desJsonFile.loadProperties().toString());
    createTable(table);

    Scheme scheme = new Scheme();
    scheme.setCreator(creatorId);
    scheme.setName(name);
    scheme.setDescription(description);
    scheme.setTable(table);
    createScheme(scheme);
    return scheme;
}