Null or zero primary key encountered in unit of work clone exception not working 解决方法

今天在开发JPA项目的时候，插入一个新的商家出现了一个奇怪的问题。

第一次插入的时候正常，然后再点击一次，插入同样的数据竟然报错：

Null or zero primary key encountered in unit of work clone exception not working

解决方法：https://stackoverflow.com/questions/15032781/null-or-zero-primary-key-encountered-in-unit-of-work-clone-exception-not-working



<?xml version="1.0" encoding="UTF-8"?>
<persistence version="2.1" xmlns="http://xmlns.jcp.org/xml/ns/persistence" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/persistence http://xmlns.jcp.org/xml/ns/persistence/persistence_2_1.xsd">
	<persistence-unit name="agency">
		<class>model.Address</class>
		<class>model.Order</class>
		<class>model.Seller</class>
		<class>model.Service</class>
		<class>model.User</class>
		<properties>
			<property name="javax.persistence.jdbc.driver" value="com.mysql.jdbc.Driver"/>
			<property name="javax.persistence.jdbc.url" value="jdbc:mysql://192.168.100.1:3306/agency?characterEncoding=UTF-8"/>
			<property name="javax.persistence.jdbc.user" value="root"/>
			<property name="javax.persistence.jdbc.password" value="root"/>
			<property name="eclipselink.allow-zero-id" value="true"/>
		</properties>
	</persistence-unit>
</persistence>