为什么未在JPA中为插入语句分配值 [英] Why Value is not getting assigned in JPA for insert statement
问题描述
我有几个实体类,如下所示,使用lombok进行吸气剂和吸气剂
Hi I have couple of Entity classes as below, using lombok for getter and setters
父实体类具有
@Table(name = "PARTY")
@Entity
public class Party {
@Id
@Column(name = "PARTY_ID")
private Long partyId;
@OneToMany(targetEntity = DVLoanParticipants.class,cascade = CascadeType.ALL)
@JoinColumn(name = "PARTY_ID")
@MapKey(name="dvpParticipantName")
@LazyCollection(LazyCollectionOption.FALSE)
private Map<String, DVLoanParticipants> dvLoanParticipantsMap;
}
子实体类具有
@Table(name = "DV_LOAN_PARTICIPANTS")
@Entity
public class DVLoanParticipants implements Serializable {
@Id
@Column(name = "PARTY_ID")
private Long partyId;
@Id
@Column(name = "DVP_PARTICIPANT_NAME")
private String dvpParticipantName;
@Column(name = "DVP_PARTICIPANT_TYPE")
private String dvpParticipantType;
}
在服务类中,我将保存操作称为
In service class i am calling save operation as
repository.save(parentEntityObject);
我能够执行更新语句,但是当我尝试为子实体类插入新行时,出现了错误提示
I am able to execute update statements ,but when i try to insert new row for child entity class i am getting an error saying
cannot insert NULL into ("ABC"."DV_LOAN_PARTICIPANTS"."PARTY_ID")
但是,如果我在保存操作之前打印出parentEntityObject,我会看到类似的值
But if i print the parentEntityObject just before the save operation i see the values like
(partyId=12345678, dvpParticipantName=XYZ, dvpParticipantType=VKP)
我看到查询形式为
insert
into
DV_LOAN_PARTICIPANTS
(DVP_PARTICIPANT_TYPE, PARTY_ID, DVP_PARTICIPANT_NAME)
values
(?, ?, ?)
就在保存之前,我在对象中看到了价值
Just before te save i am seeing valules in the Object
Builder=DVLoanParticipants(partyId=123456, dvpParticipantName=Builder,
dvpParticipantType=Individual)
更新
这是值的设置部分
DVLoanParticipants dvLoanParticipants = new
DVLoanParticipants();
dvLoanParticipants.setPartyId(Long.valueOf(partyId));
dvLoanParticipants.setDvpParticipantName("Builder");
dvLoanParticipants.setDvpParticipantType("Individual");
Party party = new Party();
Map<String, DVLoanParticipants> dvLoanParticipantsMap = new
java.util.HashMap<>();
dvLoanParticipantsMap.put("Builder", dvLoanParticipants);
party.setPartyId(Long.valueOf(partyId));
party.setDvLoanParticipantsMap(dvLoanParticipantsMap);
repository.save(party);
我在做什么错?
推荐答案
这部分问题的根本原因:
The root cause of your problem in this part:
@OneToMany(targetEntity = DVLoanParticipants.class,cascade = CascadeType.ALL)
@JoinColumn(name = "LOAN_ID")
@MapKey(name="dvpParticipantName")
private Map<String, DVLoanParticipants> dvLoanParticipantsMap;
实际上,对于您的情况, @JoinColumn 表示:
actually for your case the column name in the @JoinColumn means:
如果联接是使用外键映射策略进行的单向OneToMany映射,则外键在目标实体的表中.
因此,为清楚起见,假设您要映射以下架构:
So, assuming for the clarity that you want to map the following schema:
create table PARTY
(
PARTY_ID int,
-- ...
primary key (PARTY_ID)
);
create table DV_LOAN_PARTICIPANTS
(
PARTY_ID int,
DVP_PARTICIPANT_NAME varchar(50),
DVP_PARTICIPANT_TYPE varchar(10),
-- ...
primary key (PARTY_ID, DVP_PARTICIPANT_NAME),
foreign key (PARTY_ID) references PARTY(PARTY_ID)
);
您可以使用以下映射:
@Entity
@Table(name = "PARTY")
public class Party
{
@Id
@Column(name = "PARTY_ID")
private Long partyId;
// I use fetch = FetchType.EAGER instead of deprecated @LazyCollection(LazyCollectionOption.FALSE)
// targetEntity = DVLoanParticipants.class is redundant here
@OneToMany(cascade = CascadeType.ALL, fetch = FetchType.EAGER)
@JoinColumn(name = "PARTY_ID") // this is DV_LOAN_PARTICIPANTS.PARTY_ID column
@MapKey(name = "dvpParticipantName")
private Map<String, DVLoanParticipants> dvLoanParticipantsMap;
public Party()
{
dvLoanParticipantsMap = new HashMap<>();
}
// getters / setters
public void addParticipant(DVLoanParticipants p)
{
this.dvLoanParticipantsMap.put(p.getDvpParticipantName(), p);
p.setPartyId(getPartyId());
}
}
@Entity
@Table(name = "DV_LOAN_PARTICIPANTS")
public class DVLoanParticipants implements Serializable
{
@Id
@Column(name = "PARTY_ID")
private Long partyId;
@Id
@Column(name = "DVP_PARTICIPANT_NAME")
private String dvpParticipantName;
@Column(name = "DVP_PARTICIPANT_TYPE")
private String dvpParticipantType;
// getters / setters
}
以及如何保存的示例:
Party party = new Party();
party.setPartyId(2L);
// ...
DVLoanParticipants part1 = new DVLoanParticipants();
part1.setDvpParticipantName("Name 3");
part1.setDvpParticipantType("T1");
DVLoanParticipants part2 = new DVLoanParticipants();
part2.setDvpParticipantName("Name 4");
part2.setDvpParticipantType("T1");
party.addParticipant(part1);
party.addParticipant(part2);
repository.save(party);
和一些注意事项:
The
LazyCollectionOption.TRUE
andLazyCollectionOption.FALSE
values are deprecated since you should be using the JPAFetchType
attribute of the@OneToMany
association.
您使用特定于休眠的方法来映射综合标识符.如休眠文档:
You use hibernate specific approach for mapping сomposite identifiers. As it's mentioned in the hibernate documentation:
必须由主键类(例如,
@EmbeddedId
或@IdClass
)表示复合标识符的限制只是JPA特定于.
The restriction that a composite identifier has to be represented by a primary key class (e.g.
@EmbeddedId
or@IdClass
) is only JPA-specific.
Hibernate确实允许通过多个 @Id
属性在没有主键类的情况下定义复合标识符.
Hibernate does allow composite identifiers to be defined without a primary key class via multiple @Id
attributes.
但是,如果您想实现更多的可移植性,则应该选择一种jpa允许的方法.
But if you want to achieve more portability you should prefer one of the jpa allowed approaches.
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