正在创建如下三个实体 -
User.java
@Entity
@Table(name = "user")
public class User {
@Id
@GeneratedValue(strategy = GenerationType.AUTO)
@Column(name="user_id")
private long id;
@NotNull
private String email;
@NotNull
private String name;
@NotNull
private String contact;
//getters and setters
}
Books.java
@Entity
@Table(name="books")
public class Books {
@Id
@GeneratedValue(strategy = GenerationType.AUTO)
@Column(name="isbn")
private long isbn;
@NotNull
private String bookName;
@NotNull
private String bookDescription;
@NotNull
private String price;
//getters and setters
}
Purchases.java
@Entity
@Table(name="purchases")
public class Purchases {
@Id
@GeneratedValue(strategy = GenerationType.AUTO)
private String order_id;
@Temporal(TemporalType.TIMESTAMP)
private Date creation_time;
@OneToOne(fetch = FetchType.LAZY)
@JoinColumn(name="user_id")
private User user;
@OneToOne(fetch = FetchType.LAZY)
@JoinColumn(name="isbn")
private Books book;
// getters and setters
}
和控制器
@Controller
public class PurchaseController {
@Autowired
UserDAO userDAO;
@Autowired
BooksDAO booksDAO;
@Autowired
PurchasesDAO purchaseDAO;
@RequestMapping("/createUser")
@ResponseBody
public String createUser(String email, String name, String contact){
User user=null;
try{
user=new User(email,name,contact);
userDAO.save(user);
}catch(Exception e){
return "Problem occured while saving user :"+e;
}
return "User succesfully created! (id = " + user.getId() + ")";
}
@RequestMapping("/createBook")
@ResponseBody
public String createBooks(String bookName, String bookDesc, String price){
Books book=null;
try{
book=new Books(bookName,bookDesc,price);
booksDAO.save(book);
}catch(Exception e){
return "Problem occured while saving book details :"+e;
}
return "Book succesfully created! (isbn = " + book.getIsbn() + " name = "+book.getBookName()+")";
}
@RequestMapping("/purchase")
@ResponseBody
public String purchase(Long user_id, Long isbn){
Books book=null;
User user=null;
Purchases purchase=null;
Date creation_date=new Date();
try{
book=booksDAO.findOne(isbn);
user=userDAO.findOne(user_id);
System.out.println("book= "+book+" and user= "+user+"");
if(book.getIsbn()==0 || user.getId()==0){
return "Book with isbn="+isbn+" or user with user id ="+user_id+" not found.";
}
purchase = new Purchases(creation_date,user,book);
purchaseDAO.save(purchase);
}catch(Exception e){
return "Exception occured while purchasing book ["+e+"]";
}
return "Book purchased";
}}
dao接口扩展CrudRepository<Class, Long>{}，注释为transactional。问题是第三个表是purchase.java没有被创建。在控制台上获取以下内容。
2016-05-03 18:13:33.876 INFO 19570 --- [ main] o.hibernate.jpa.internal.util.LogHelper : HHH000204: Processing PersistenceUnitInfo [
name: default
...]
2016-05-03 18:13:33.920 INFO 19570 --- [ main] org.hibernate.Version : HHH000412: Hibernate Core {4.3.8.Final}
2016-05-03 18:13:33.921 INFO 19570 --- [ main] org.hibernate.cfg.Environment : HHH000206: hibernate.properties not found
2016-05-03 18:13:33.922 INFO 19570 --- [ main] org.hibernate.cfg.Environment : HHH000021: Bytecode provider name : javassist
2016-05-03 18:13:34.062 INFO 19570 --- [ main] o.hibernate.annotations.common.Version : HCANN000001: Hibernate Commons Annotations {4.0.5.Final}
2016-05-03 18:13:34.388 INFO 19570 --- [ main] org.hibernate.dialect.Dialect : HHH000400: Using dialect: org.hibernate.dialect.MySQL5Dialect
2016-05-03 18:13:34.465 INFO 19570 --- [ main] o.h.h.i.ast.ASTQueryTranslatorFactory : HHH000397: Using ASTQueryTranslatorFactory
2016-05-03 18:13:34.707 INFO 19570 --- [ main] org.hibernate.tool.hbm2ddl.SchemaExport : HHH000227: Running hbm2ddl schema export
Hibernate: alter table purchases drop foreign key FK_laat6sjwiu2hcenno94vyj0jb
2016-05-03 18:13:34.716 ERROR 19570 --- [ main] org.hibernate.tool.hbm2ddl.SchemaExport : HHH000389: Unsuccessful: alter table purchases drop foreign key FK_laat6sjwiu2hcenno94vyj0jb
2016-05-03 18:13:34.716 ERROR 19570 --- [ main] org.hibernate.tool.hbm2ddl.SchemaExport : Table 'purchase_books.purchases' doesn't exist
Hibernate: alter table purchases drop foreign key FK_klpjcob070n95mdvt1473hs1s
2016-05-03 18:13:34.716 ERROR 19570 --- [ main] org.hibernate.tool.hbm2ddl.SchemaExport : HHH000389: Unsuccessful: alter table purchases drop foreign key FK_klpjcob070n95mdvt1473hs1s
2016-05-03 18:13:34.716 ERROR 19570 --- [ main] org.hibernate.tool.hbm2ddl.SchemaExport : Table 'purchase_books.purchases' doesn't exist
Hibernate: drop table if exists books
Hibernate: drop table if exists purchases
Hibernate: drop table if exists user_details
Hibernate: create table books (isbn bigint not null auto_increment, book_description varchar(255) not null, book_name varchar(255) not null, price varchar(255) not null, primary key (isbn))
Hibernate: create table purchases (order_id bigint not null auto_increment, creation_time datetime, isbn bigint, user_id bigint, primary key (order_id))
Hibernate: create table user_details (user_id bigint not null auto_increment, contact varchar(255) not null, email varchar(255) not null, name varchar(255) not null, primary key (user_id))
Hibernate: alter table purchases add constraint FK_laat6sjwiu2hcenno94vyj0jb foreign key (isbn) references books (isbn)
Hibernate: alter table purchases add constraint FK_klpjcob070n95mdvt1473hs1s foreign key (user_id) references user_details (user_id)
2016-05-03 18:13:37.037 INFO 19570 --- [ main] org.hibernate.tool.hbm2ddl.SchemaExport : HHH000230: Schema export complete
使用SpringBoot运行应用程序。在消息中提到了问题，但无法弄清楚。任何人都可以详细说明或告诉如何解决这个问题？表是在sql数据库中使用hibernate创建的。
答案 0 :(得分：1)
检查“购买”order_id上的类型。我想你可能希望它是一个数字，也许是类型＆＃34; long＆＃34;。
答案 1 :(得分：0)
无法将@GeneratedValue(strategy = GenerationType.AUTO)用于String属性
@Id
@GeneratedValue(strategy = GenerationType.AUTO)
private String order_id;
将其更改为Long，例如
@Id
@GeneratedValue(strategy = GenerationType.AUTO)
private Long order_id;
请不要使用user等表名。它是PostgreSQL中的保留关键字。