我试图在两个对象之间创建一对多关系，但是我遇到了这个错误。我不知道如何将对象MyUserAccount中的属性ID映射到对象Book。 ID是从Google收到的字符串数据（我在我的项目中进行社交登录）。
错误
PreparedStatementCallback; SQL [INSERT INTO Books(TENSACH, TACGIA, NHANXET, TINHTRANG, THELOAI, IMAGE, IMAGE_NAME) VALUES ( ?, ?, ?, ?, ?, ?, ?)]; Field 'ID' doesn't have a default value; nested exception is java.sql.SQLException: Field 'ID' doesn't have a default value
BookDao（如何将对象簿保存到数据库中）
public void save(Book book) {
// TODO Auto-generated method stub
KeyHolder keyHolder = new GeneratedKeyHolder();
String sql = "INSERT INTO Books(TENSACH, TACGIA, NHANXET, TINHTRANG, THELOAI, IMAGE, IMAGE_NAME) "
+ "VALUES ( :tensach, :tacgia, :nhanxet, :tinhtrang, :theloai, :image, :image_name)";
namedParameterJdbcTemplate.update(sql, getSqlParameterByModel(book), keyHolder);
book.setBook_ID(keyHolder.getKey().intValue());
}
private SqlParameterSource getSqlParameterByModel(Book book) {
MapSqlParameterSource paramSource = new MapSqlParameterSource();
paramSource.addValue("book_id", book.getBook_ID());
paramSource.addValue("tensach", book.getTensach());
paramSource.addValue("tacgia", book.getTacgia());
paramSource.addValue("nhanxet", book.getNhanxet());
paramSource.addValue("tinhtrang", book.getTinhtrang());
paramSource.addValue("image", book.getImage());
paramSource.addValue("image_name", book.getImage_name());
paramSource.addValue("theloai", book.getTheloai());
return paramSource;
}
模特书
public class Book implements Serializable {
private static final long serialVersionUID = 1L;
private Integer book_ID;
private String tensach;
private String tacgia;
private String nhanxet;
private String tinhtrang;
private String theloai;
private byte[] image;
private String image_name;
private String data;
private MyUserAccount myUserAccount;
public Book() {
}
@ManyToOne(fetch = FetchType.LAZY)
@JoinColumn(name = "ID", nullable = false)
public MyUserAccount getMyUserAccount() {
return this.myUserAccount;
}
public void setMyUserAccount(MyUserAccount myUserAccount) {
this.myUserAccount = myUserAccount;
}
@Id
@GeneratedValue(strategy = IDENTITY)
@Column(name = "book_id", unique = true, nullable = false)
public Integer getBook_ID() {
return book_ID;
}
@Column(name = "image_name")
public String getImage_name() {
return image_name;
}
@Column(name = "tensach", length = 50, nullable = true)
public String getTensach() {
return tensach;
}
@Lob
@Type(type = "org.hibernate.type.BinaryType")
@Column(name = "image", columnDefinition = "LONGBLOB", nullable = true)
public byte[] getImage() {
return image;
}
@Column(name = "tacgia", length = 50, nullable = true)
public String getTacgia() {
return tacgia;
}
@Column(name = "nhanxet", length = 100, nullable = true)
public String getNhanxet() {
return nhanxet;
}
@Column(name = "tinhtrang", length = 50, nullable = true)
public String getTinhtrang() {
return tinhtrang;
}
@Column(name = "theloai", length = 50, nullable = true)
public String getTheloai() {
return theloai;
}
@Column(name = "data", length = 16777215)
public String getData() {
return data;
}
public void setBook_ID(Integer book_ID) {
this.book_ID = book_ID;
}
public void setImage_name(String image_name) {
this.image_name = image_name;
}
public void setImage(byte[] image) {
this.image = image;
}
public void setTensach(String tensach) {
this.tensach = tensach;
}
public void setTacgia(String tacgia) {
this.tacgia = tacgia;
}
public void setNhanxet(String nhanxet) {
this.nhanxet = nhanxet;
}
public void setTinhtrang(String tinhtrang) {
this.tinhtrang = tinhtrang;
}
public void setTheloai(String theloai) {
this.theloai = theloai;
}
public void setData(String data) {
this.data = data;
}
@Override
public String toString() {
return "Book [book_ID=" + book_ID + ", tensach=" + tensach + ", tacgia=" + tacgia + ", nhanxet=" + nhanxet
+ ", tinhtrang=" + tinhtrang + ", theloai=" + theloai + ", image=" + Arrays.toString(image) + "]";
}
}
模型MyUserAccount。
public class MyUserAccount implements Serializable {
private static final long serialVersionUID = 1L;
public static final String ROLE_USER = "ROLE_USER";
private String id;
private String email;
private String userName;
private String firstName;
private String lastName;
private String password;
private String role;
private String enabled;
private List<Book> book = new ArrayList<Book>(0);
public MyUserAccount() {
}
@OneToMany(fetch = FetchType.LAZY, mappedBy = "myUserAccount")
public List<Book> getBook() {
return book;
}
public void setBook(List<Book> book) {
this.book = book;
}
public MyUserAccount(String id, String email, String userName, String firstName, //
String lastName, String password, String role, String enabled) {
this.id = id;
this.email = email;
this.userName = userName;
this.firstName = firstName;
this.lastName = lastName;
this.password = password;
this.role = role;
this.enabled = enabled;
}
@Id
@Column(name = "ID", unique = true, nullable = false)
public String getId() {
return id;
}
public void setId(String id) {
this.id = id;
}
@Column(name = "EMAIL", unique = true, nullable = false)
public String getEmail() {
return email;
}
public void setEmail(String email) {
this.email = email;
}
@Column(name = "USER_NAME", unique = true, nullable = false)
public String getUserName() {
return userName;
}
public void setUserName(String userName) {
this.userName = userName;
}
@Column(name = "FIRST_NAME", nullable = false)
public String getFirstName() {
return firstName;
}
public void setFirstName(String firstName) {
this.firstName = firstName;
}
@Column(name = "LAST_NAME", nullable = false)
public String getLastName() {
return lastName;
}
public void setLastName(String lastName) {
this.lastName = lastName;
}
@Column(name = "PASSWORD", nullable = false)
public String getPassword() {
return password;
}
public void setPassword(String password) {
this.password = password;
}
@Column(name = "ROLE", nullable = false)
public String getRole() {
return role;
}
public void setRole(String role) {
this.role = role;
}
@Column(name = "ENABLED", columnDefinition = "VARCHAR(1) default 'Y'", nullable = false)
public String getEnabled() {
return enabled;
}
public void setEnabled(String enabled) {
this.enabled = enabled;
}
}
控制器
@RequestMapping(value = "/motsach/add/", method = RequestMethod.POST)
public String saveBook(@ModelAttribute("bookForm") @Validated Book book, BindingResult result, Model model,
@RequestParam CommonsMultipartFile[] image, String userName, final RedirectAttributes redirectAttributes)
throws IOException, UnsupportedEncodingException {
MyUserAccount myUserAccount = myUserAccountDAO.findByUserName(userName);
System.out.println(userName + "sssssssssssss");
book.setMyUserAccount(myUserAccount);
redirectAttributes.addFlashAttribute("css", "success");
if (book.getBook_ID() == null) {
System.out.println(book.getBook_ID());
redirectAttributes.addFlashAttribute("msg", "book added successfully!");
} else {
redirectAttributes.addFlashAttribute("msg", "book updated successfully!");
}
for (CommonsMultipartFile aFile : image) {
System.out.println("Saving file: " + aFile.getOriginalFilename());
book.setImage_name(aFile.getOriginalFilename());
book.setImage(aFile.getBytes());
System.out.println("Damn that Shit!");
}
bookService.saveOrUpdate(book);
// POST/REDIRECT/GET
return "redirect:/motsach/" + book.getBook_ID();
}
答案 0 :(得分：1)
您有@manyToOne（ID为名称）关系，不能为空。因此，为了添加图书，您必须在保存之前将MyUserAccount设置为图书，否则您可以转为：
@ManyToOne(fetch = FetchType.LAZY)
@JoinColumn(name = "ID", nullable = true)
public MyUserAccount getMyUserAccount() {
return this.myUserAccount;
}
并修改数据库中的列以设置空值的可能性。