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[英]java.sql.SQLException: Field 'participant_one_fk_id' doesn't have a default value
[英]“java.sql.SQLException: Field 'id_parent' doesn't have a default value” with one-to-many relationship mapping
是的,這樣的標題問題在SO上出現了幾次。 但是,到目前為止,這些解決方案都沒有起作用。 我試圖重新創建表並更改/etc/my.cnf文件。
/etc/my.cnf中:
datadir=/var/lib/mysql
socket=/var/lib/mysql/mysql.sock
symbolic-links=0
sql_mode=NO_ENGINE_SUBSTITUTION
下面的程序應創建父對象,將其存儲在數據庫中,檢索它,將子對象附加到該對象,並使用session.save(parent)隱式地將父對象與其子對象存儲在一起。 崩潰點在源代碼(Main.java)中顯示為注釋。
數據庫構造函數腳本:
SET @OLD_UNIQUE_CHECKS=@@UNIQUE_CHECKS, UNIQUE_CHECKS=0;
SET @OLD_FOREIGN_KEY_CHECKS=@@FOREIGN_KEY_CHECKS, FOREIGN_KEY_CHECKS=0;
SET @OLD_SQL_MODE=@@SQL_MODE, SQL_MODE='TRADITIONAL,ALLOW_INVALID_DATES';
CREATE SCHEMA IF NOT EXISTS `dvsscce` ;
USE `dvsscce` ;
CREATE TABLE IF NOT EXISTS `dvsscce`.`parents` (
`id_parent` INT UNSIGNED NOT NULL AUTO_INCREMENT,
`attribute1` VARCHAR(45) NULL,
`attribute2` VARCHAR(45) NULL,
PRIMARY KEY (`id_parent`))
ENGINE = InnoDB
AUTO_INCREMENT = 1;
CREATE TABLE IF NOT EXISTS `dvsscce`.`children` (
`id_child` INT UNSIGNED NOT NULL AUTO_INCREMENT,
`id_parent` INT UNSIGNED NOT NULL,
`attribute3` VARCHAR(45) NULL,
PRIMARY KEY (`id_child`, `id_parent`),
INDEX `fk_children_parent_idx` (`id_parent` ASC),
CONSTRAINT `fk_children_parent`
FOREIGN KEY (`id_parent`)
REFERENCES `dvsscce`.`parents` (`id_parent`)
ON DELETE CASCADE
ON UPDATE CASCADE)
ENGINE = InnoDB
AUTO_INCREMENT = 1;
SET SQL_MODE=@OLD_SQL_MODE;
SET FOREIGN_KEY_CHECKS=@OLD_FOREIGN_KEY_CHECKS;
SET UNIQUE_CHECKS=@OLD_UNIQUE_CHECKS;
Main.java:
public class Main {
public static void insertParent(Parent p)
{
Session session = SessionContainer.factory.openSession();
Transaction tx = null;
try
{
tx = session.beginTransaction();
session.saveOrUpdate(p);
tx.commit();
}
catch(HibernateException he)
{
if (tx != null) tx.rollback();
he.printStackTrace();
}
finally
{
session.close();
}
}
public static void insertChild(Parent p, Child c)
{
Session session = SessionContainer.factory.openSession();
Transaction tx = null;
try
{
tx = session.beginTransaction();
Query query = session.createQuery("FROM com.mycompany.dvnfsscce.Parent p WHERE p.id = :id_parent");
query.setParameter("id_parent", p.getId());
List results = query.list();
Parent parent = (Parent)results.get(0);
List<Child> finalList = parent.getChildren();
finalList.add(c);
parent.setChildren(finalList);
session.update(parent);
tx.commit(); //crashpoint
}
catch(HibernateException he)
{
if (tx != null) tx.rollback();
he.printStackTrace();
}
finally
{
session.close();
}
}
public static void main(String[] args)
{
Parent parent = new Parent();
parent.setAttribute1("foo");
parent.setAttribute2("bar");
insertParent(parent);
Child child = new Child();
child.setAttribute3(("Quick brown fox"));
insertChild(parent,child);
}
}
Parent.java:
public class Parent {
private int id;
private String attribute1;
private String attribute2;
private List<Child> children = new ArrayList<>();
// Getters and setters not pasted...
}
Child.java
public class Child {
private int id;
private String attribute3;
// Getters and setters not pasted...
}
child.hbm.xml
<hibernate-mapping package="com.mycompany.dvnfsscce">
<class name="Child" table="children">
<id name="id" type="int">
<column name="id_child"/>
<generator class="native"/>
</id>
<property name="attribute3" column="attribute3" type="string"/>
</class>
</hibernate-mapping>
parent.hbm.xml
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN" "http://www.hibernate.org/dtd/hibernate-mapping-3.0.dtd">
<hibernate-mapping package="com.mycompany.dvnfsscce">
<class name="Parent" table="parents">
<id name="id" type="int">
<column name="id_parent" not-null="true"/>
<generator class="native"/>
</id>
<property name="attribute1" column="attribute1" type="string"/>
<property name="attribute2" column="attribute2" type="string"/>
<bag name="children" cascade="all" table="children">
<key>
<column name="id_parent" not-null="true" />
</key>
<one-to-many class="Child"/>
</bag>
</class>
</hibernate-mapping>
log4j日志文件:
21:59:24,791 TRACE TypeFactory:72 - Scoping types to session factory org.hibernate.internal.SessionFactoryImpl@4b41dd5c
21:59:36,934 TRACE BasicBinder:81 - binding parameter [1] as [VARCHAR] - [foo]
21:59:36,934 TRACE BasicBinder:81 - binding parameter [2] as [VARCHAR] - [bar]
22:00:22,540 TRACE BasicBinder:81 - binding parameter [1] as [INTEGER] - [1]
22:00:22,634 TRACE BasicExtractor:78 - extracted value ([id_paren1_1_] : [INTEGER]) - [1]
22:00:22,649 TRACE BasicExtractor:78 - extracted value ([attribut2_1_] : [VARCHAR]) - [foo]
22:00:22,649 TRACE BasicExtractor:78 - extracted value ([attribut3_1_] : [VARCHAR]) - [bar]
22:00:22,665 TRACE CollectionType:783 - Created collection wrapper: [com.mycompany.dvnfsscce.Parent.children#1]
22:00:27,462 TRACE BasicBinder:81 - binding parameter [1] as [INTEGER] - [1]
22:06:42,595 TRACE BasicBinder:81 - binding parameter [1] as [VARCHAR] - [Quick brown fox]
22:06:42,781 WARN SqlExceptionHelper:144 - SQL Error: 1364, SQLState: HY000
22:06:42,782 ERROR SqlExceptionHelper:146 - Field 'id_parent' doesn't have a default value
輸出:
Hibernate:
/* insert com.mycompany.dvnfsscce.Parent
*/ insert
into
parents
(attribute1, attribute2)
values
(?, ?)
Hibernate:
/*
FROM
com.mycompany.dvnfsscce.Parent p
WHERE
p.id = :id_parent */ select
parent0_.id_parent as id_paren1_1_,
parent0_.attribute1 as attribut2_1_,
parent0_.attribute2 as attribut3_1_
from
parents parent0_
where
parent0_.id_parent=?
Hibernate:
select
children0_.id_parent as id_paren3_1_0_,
children0_.id_child as id_child1_0_0_,
children0_.id_child as id_child1_0_1_,
children0_.attribute3 as attribut2_0_1_
from
children children0_
where
children0_.id_parent=?
Hibernate:
/* insert com.mycompany.dvnfsscce.Child
*/ insert
into
children
(attribute3)
values
(?)
在表子級中,您將“ id_parent”定義為不為null且沒有默認值。
`id_parent` INT UNSIGNED NOT NULL,
從最后的休眠日志中可以注意到,試圖插入只有一列的子表。
Hibernate:
into children (attribute3) values (?)
在這種情況下,id_parent將為null,這是不允許的。 可能的解決方案是刪除NOT NULL限制,或在insertChildren中正確分配父ID:
public static void insertChild(Parent p, Child c) {
Session session = SessionContainer.factory.openSession();
Transaction tx = null;
try {
tx = session.beginTransaction();
Query query = session.createQuery("FROM com.mycompany.dvnfsscce.Parent p WHERE p.id = :id_parent");
query.setParameter("id_parent", p.getId());
List results = query.list();
Parent parent = (Parent)results.get(0);
// Here we set the id.
c.setIdParent(parent.getId());
List<Child> finalList = parent.getChildren();
finalList.add(c);
parent.setChildren(finalList);
session.update(parent);
tx.commit(); //crashpoint
} catch(HibernateException he) {
if (tx != null) tx.rollback();
he.printStackTrace();
} finally {
session.close();
}
}
再說一次,由於這是雙向關系,因此將其映射為這樣很好:
<class name="Parent" table="parents">
<id name="id" type="int">
<column name="id_parent" not-null="true"/>
<generator class="native"/>
</id>
<property name="attribute1" column="attribute1" type="string"/>
<property name="attribute2" column="attribute2" type="string"/>
<set name="children" inverse="true" cascade="all">
<key column="id_parent" not-null="true" />
<one-to-many class="Child"/>
</set>
</class>
<class name="Child" table="children">
<id name="id" type="int">
<column name="id_child"/>
<generator class="native"/>
</id>
<property name="attribute3" column="attribute3" type="string"/>
<many-to-one name="parent" class="Parent" column="id_parent" not-null="true"/>
</class>
然后,您在Child中定義一個帶有適當的setters / getters的字段Parent(並且可能由於總是需要構造函數而需要使用parent):
public class Child {
private int id;
private String attribute3;
private Parent parent;
// Getters and setters not pasted...
public Child(Parent parent) {
this.setParent(parent);
}
}
最后回到主要:
Child child = new Child(parent);
您現在可以刪除
c.setIdParent(parent.getId());
在上面我提到的insertChild()中,所有都應該是桃子。
作為旁注,我建議使用批注,因為這樣可以更容易地獲得在同一位置具有字段和映射的Bean映射的概述:)
Parent
是關聯的擁有方(這是唯一的一方,因此它必須是擁有方)。 由於join列不是屬於關聯所有者的實體的一部分,因此Hibernate會在看到Parent
和Child
關聯到Parent
的children
集合中時生成一個update語句來關聯Parent
和Child
。
這就是為什么在沒有聯接列的值的情況下進行Child
插入的原因(數據庫抱怨,因為它不可為空)。
你應該讓聯想雙向的,申報的many
方面是關聯的所有者(通過使one
側inverse
)。 這樣,您可以避免嘗試為連接列存儲null
並擺脫附加的update語句。
或者,要保持您當前的映射不變,只需使join列可為空(但您可以松開約束並執行不必要的update語句)。
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