问题描述
我有一个教师表,其中包含一个主键 TEACHER_UNIQUE_ID,以及另一个索引为 TEACHER_ID 的自动增量键.现在我必须将 autoIncrement 键映射到其他表,即 SUBJECT .我使用了下面的代码,但这总是在主题类中将 TEACHER_ID 设置为 null.
I have a teacher table, where it contains one primary key TEACHER_UNIQUE_ID,and other one autoIncrement key with Index TEACHER_ID.Now i have to map autoIncrement key to other table i.e SUBJECT . I have used below code, but this always sets TEACHER_ID as null in subject class.
我希望它插入带有实际 autoIncremented TEACHER_ID 的主题表.
i want it to insert Subject table with actual autoIncremented TEACHER_ID.
public class Teacher {
@Id
@Column(name = "TEACHER_UNIQUE_ID")
private String teacherUniqueId;
@GeneratedValue(strategy = GenerationType.AUTO)
@Column(name = "TEACHER_ID", unique = true)
private Long teacherId;
-----
-----
@OneToMany(cascade = CascadeType.ALL, fetch=FetchType.EAGER, mappedBy="teacher" ,orphanRemoval = true)
@Fetch(FetchMode.SELECT)
@MapKey(name = "fieldName")
private Map<String, subject> subjectInfo = new HashMap<>(0);
public Long getTeacherUniqueId() {
return teacherUniqueId;
}
public void setTeacherUniqueId(Long teacherUniqueId) {
this.teacherUniqueId = teacherUniqueId;
}
public Long getTeacherId() {
return teacherId;
}
public void setTeacherId(Long teacherId) {
this.teacherId = teacherId;
}
private void setField(String key, String value) {
subject subjectInfoData = subjectInfo.get(key);
if(subjectInfoData == null){
subjectInfoData = new subject();
subjectInfoData.setFieldName(key);
subjectInfo.put(key, subjectInfoData);
}
subjectInfoData.setTeacher(this);
**subjectInfoData.setId(this.getTeacherId());** -- its inserting null to id in SUBJECT table. i want it to insert actual TEACHER_ID got from TEACHER Table.
subjectInfoData.setFieldValue(value);
setAdditionalInfo(subjectInfo);
}
public String getCustomFieldValue(String fieldName) {
return subjectInfo.get(fieldName)!=null?subjectInfo.get(fieldName).getFieldValue():null;
}
public void setCustomFieldValue(String fieldName, String fieldValue) {
setField(fieldName, fieldValue);
}
public Map<String, Subject> getAdditionalInfo() {
return subjectInfo;
}
public void setAdditionalInfo(Map<String, Subject> subjectInfo) {
this.subjectInfo = subjectInfo;
}
}
除 TEACHER_ID 外,其他值都正确插入.
Other values are inserting properly except TEACHER_ID.
我试过了
@GenericGenerator(name="generator", strategy="increment")
@GeneratedValue(generator="generator")
@Column(name = "TEACHER_ID", unique = true)
private Long teacherId;
还有这个
@GeneratedValue(strategy = GenerationType.AUTO)
@Column(name = "TEACHER_ID", unique = true)
private Long teacherId;
没有运气.谁能告诉我我在这里缺少什么.
No luck. Can anyone tell me what i am missing here.
推荐答案
解决这个问题:我希望它插入带有实际 autoIncremented TEACHER_ID 的主题表."
To solve this problem:"I want it to insert the Subject table with actual autoIncremented TEACHER_ID."
我建议在数据库中保留一个序列对象来手动跟踪增量.
I would suggest keeping a sequence object in the database to manually track the increment.
使用 Hibernate 自动生成 ID:
To generate ID automatically using Hibernate:
1) 在您的数据库开发人员(SQL 开发人员)中创建一个序列对象.
1) Create a sequence object in your database developer(SQL developer).
2) 将此代码添加到 id 变量:
2) Add this code to id variable:
@Id
@Column(name = "ID")
@GeneratedValue(strategy = GenerationType.SEQUENCE, generator = "ONE")
@SequenceGenerator(name = "ONE", sequenceName = "ONE", allocationSize =1)
int id;
3) ‘ONE’是序列的名字,我创建了你可以随意命名,分配大小是按数字递增.
3) ‘ONE’ is the name of the sequence, I have created you can name it whatever you want and allocation Size is the increment by number.
4) 将值插入数据库(教师 ID)时,发送 0 代替 Id,Hibernate 将自动从序列号转换该值.现在您可以使用这个数字来填充主题表.
4) When inserting the values into the database (Teacher ID) send 0 in place of Id and Hibernate will automatically translate the value from the sequence number.Now you can use this number to populate the subject table.
注意:在教师表中插入新对象时将返回 ID.使用该 ID,您可以填充主题表.有时最好用旧的方式来做,而不是使用 spring 已经提供的注释.
希望这能节省您的时间!
Hope this saves your time!
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