我正在开发Spring-MVC应用程序，并且其中有多对多映射。有3个表，一个是GroupAccount，memberjunction，GroupMembers。现在，当我删除groupMember时，我只想从GroupMembers和与memberId对应的memberjunction中删除条目。我尝试使用Cascade.Remove，它也导致了GroupAccount的删除。我正在发布我的sql代码，以及到目前为止的内容。
SQL代码：
CREATE TABLE groupaccount
(
groupid numeric NOT NULL,
groupname character varying,
adminusername character varying,
CONSTRAINT groupid PRIMARY KEY (groupid)
)
CREATE TABLE memberjunction
(
memberid integer NOT NULL,
groupid numeric NOT NULL,
CONSTRAINT membergroupid PRIMARY KEY (memberid, groupid),
CONSTRAINT groupaccount_memberjunction_fk FOREIGN KEY (groupid)
REFERENCES groupaccount (groupid) MATCH SIMPLE
ON UPDATE NO ACTION ON DELETE NO ACTION,
CONSTRAINT groupmembers_memberjunction_fk FOREIGN KEY (memberid)
REFERENCES groupmembers (memberid) MATCH SIMPLE
ON UPDATE NO ACTION ON DELETE NO ACTION
)
CREATE TABLE groupmembers
(
memberid integer NOT NULL,
musername character varying,
accesslevel boolean DEFAULT true,
CONSTRAINT memberid PRIMARY KEY (memberid)
)
GroupMembersDAOImpl删除方法：
@Override
public boolean removeGroupMember(int memberId) {
session = sessionFactory.getCurrentSession();
GroupMembers groupMembers = (GroupMembers) session.get(GroupMembers.class, memberId);
if(!(groupMembers == null)){
groupMembers.getGroupAccounts().clear();
session.flush();
session.delete(groupMembers);
return true;
} else {
return false;
}
}
GroupAccount实体：
@Entity
@Table(name="groupaccount")
public class GroupAccount {
@Id
@Column(name="groupid")
@GeneratedValue(strategy = GenerationType.SEQUENCE,generator = "groupaccount_seq_gen")
@SequenceGenerator(name = "groupaccount_seq_gen",sequenceName = "groupaccount_seq")
private Long groupId;
@ManyToMany(cascade = CascadeType.ALL)
@JoinTable(name = "memberjunction", joinColumns = {@JoinColumn(name = "groupid")},
inverseJoinColumns = {@JoinColumn(name = "memberid")})
private Set<GroupMembers> groupMembersSet = new HashSet<>();
public void setGroupMembersSet(Set<GroupMembers> groupMembersSet){
this.groupMembersSet = groupMembersSet;
}
public Set<GroupMembers> getGroupMembersSet(){
return this.groupMembersSet;
}
}
GroupMembers实体：
@Entity
@Table(name="groupmembers")
public class GroupMembers {
@Id
@Column(name="memberid")
@GeneratedValue(strategy = GenerationType.SEQUENCE,generator = "groupmembers_seq_gen")
@SequenceGenerator(name = "groupmembers_seq_gen",sequenceName = "groupmembers_seq")
private int memberid;
@ManyToMany(mappedBy = "groupMembersSet")
private Set<GroupAccount> groupAccounts = new HashSet<>();
public void setGroupAccounts(Set<GroupAccount> groupAccounts){
this.groupAccounts = groupAccounts;
}
public Set<GroupAccount> getGroupAccounts(){
return this.groupAccounts;
}
}
最新错误日志：
org.postgresql.util.PSQLException: ERROR: update or delete on table "groupmembers" violates foreign key constraint "groupmembers_memberjunction_fk" on table "memberjunction"
Detail: Key (memberid)=(2501) is still referenced from table "memberjunction".
org.postgresql.core.v3.QueryExecutorImpl.receiveErrorResponse(QueryExecutorImpl.java:2198)
org.postgresql.core.v3.QueryExecutorImpl.processResults(QueryExecutorImpl.java:1927)
上面的方法无法正常工作，正如它说的那样，有对memberJunction的引用。我如何也查询memberJunction并删除与memberId对应的条目。你能帮忙的话，我会很高兴。非常感谢.. ：-）
您需要执行以下操作：
for(GroupAccount groupAccount : groupMembers.getGroupAccounts()) {
groupAccount.getGroupMembersSet().remove(this);
}
groupMembers.getGroupAccounts().clear();
session.flush();
session.delete(groupMembers);
因为您具有@ManyToMany关联，所以关联表在运行时不可用。为此，您可以：
在删除GroupMembers之前清除GroupAccountsfrom GroupMembers。确保刷新，以确保delete操作不会阻止对可删除实体状态的更新。
您可以将替换为@ManyToMany与实体的@OneToMany关联MemberJunction（其PK / @ Id是通过GroupMembers和构建的GroupAccount）。这样，您可以将Delete from层叠GroupMembers到MemberJunction mappedBySet中，因为它将删除关联表中的行，而不是实际的GroupAccount实体。
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