Hibernate saveOrUpdate命令将现有行的字段更改为NULL [英] Hibernate saveOrUpdate command changes fields of existing row to NULL

问题描述

我有一个对象作为另一个对象的成员，可以说Object1和Object 2.
对象2在对象1中，并且有3个字段。

我从用户处收到对象1的详细信息。
也ID和从用户对象2的名称和需要保存Object1在DB所以我用
session.saveOrUpdate（object1），

但它保存object1并保留用户提供的对象2的文件，并将其他文件更改为NULL。

我是否应该通过Object2的所有文件来避免这个问题，或者是否有办法阻止将这些字段更改为NULL并保留其值的休眠？ b
$ b'pre> Object1

ID
名称
@ManyToOne（级联= CascadeType.ALL）
Object2

Object2

ID
名称
年龄


示例

DB

Object2的ID = 13 name = XYZ age = 32

用户输入

Object1 name = Jack

Object2 ID = 13 name = XYZ

保存object1后，object2将如下

Object2 ID = 13 name = XYZ age = NULL
（a）如果Object1已经存在于数据库中，那么检索它：
$ b $ b

  Object1 obj1 = session.find（...）; 
  

（b）否则，如果Object1是新的，那么创建它：

  Object1 obj1 = new Object1（）; 
  

通过调用setter方法填充obj1字段

$ b

（a）如果Object2已经存在于DB中，则加载它：

  Object2 obj2 = obj1 .getObject2（）; //确保object2加载; 
 //如果需要，则延迟加载（例如，一对多）
  

（b ）else，如果Object2是新的，那么创建它，并将它附加到Object1中：
$ b

  Object2 obj2 = new Object2（）; 
 obj1.setObject2（obj2）; 
  

通过调用setter方法填充obj2字段

$ b

如果Object1到Object2的关系具有级联更新OR ALL：

  session.saveOrUpdate（OBJ1）; 
  

3a）（或者你在做（3a），但是用（3b）替换它）。

I have an object as member of another object, lets say Object1 and Object 2. Object 2 is in Object 1, and has 3 fields.

I receive the details of Object 1 from user. Also ID and name of object 2 from user and need to save the Object1 in the DB so I use session.saveOrUpdate(object1),

but it saves object1 and keep the fileds of object 2 that user provided and change the other fileds to NULL.

Should I pass all the fileds of Object2 avoid this problem or is there a way of preventing hibernate of changing those fields to NULL and keep their values ?

Object1

 ID
 name
 @ManyToOne (cascade = CascadeType.ALL)
 Object2

Object2

  ID 
  name
  age

Example

What I have in DB

Object2 has ID =13 name=XYZ age=32

User enters

Object1 name = Jack

Object2 ID = 13 name=XYZ

After saving object1, the object2 will be as following

Object2 ID = 13 name=XYZ age=NULL

解决方案

1. (a) If Object1 already exists in DB, then retrieve it:

   Object1 obj1 = session.find(...);
   

   (b) else, if Object1 is new then create it:

   Object1 obj1 = new Object1();
   

2. Populate obj1 fields, by calling setter methods

3. (a) If Object2 already exists in DB, then load it:

   Object2 obj2 = obj1.getObject2();  // ensures object2 loaded; 
                                      // does lazy load if required (e.g. one-to-many)
   

   (b) else, if Object2 is new then create it, and attach it to Object1:

   Object2 obj2 = new Object2();
   obj1.setObject2(obj2);
   

4. Populate obj2 fields, by calling setter methods

5. If Object1 to Object2 relationship has Cascade UPDATE OR ALL:

   session.saveOrUpdate(obj1);
   

You're not doing (3a) (or you're doing (3a), but then replacing it with (3b)).

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