Question

我在休眠状态下建立一对多关系，但是当我尝试插入一个值时在表中，我得到一个例外，即我的FK in photos实体不能为null。

我的父实体：

@Table(name = "library")
@Entity
public class Book {
@OneToMany(
        fetch = FetchType.LAZY,
        mappedBy = "book",
        cascade = CascadeType.ALL,
        orphanRemoval = true
)
// setters / getters and other columns

我的孩子实体

@Entity
@Table(name = "photos")
public class photos{
@Id
@GeneratedValue(strategy = GenerationType.AUTO)
@Column(name = "idphotos")
private int id;


@ManyToOne(cascade = CascadeType.ALL,fetch = FetchType.LAZY)
@JoinColumn(name = "library_idlibrary")
private Book book;
// other columns

例外：

java.sql.SQLIntegrityConstraintViolationException: Column 'library_idlibrary' cannot be null
com.mysql.cj.jdbc.exceptions.SQLError.createSQLException(SQLError.java:115)
com.mysql.cj.jdbc.exceptions.SQLError.createSQLException(SQLError.java:95)
com.mysql.cj.jdbc.exceptions.SQLExceptionsMapping.translateException(SQLExceptionsMapping.java:122)
com.mysql.cj.jdbc.ClientPreparedStatement.executeInternal(ClientPreparedStatement.java:960)
com.mysql.cj.jdbc.ClientPreparedStatement.executeUpdateInternal(ClientPreparedStatement.java:1116)
com.mysql.cj.jdbc.ClientPreparedStatement.executeUpdateInternal(ClientPreparedStatement.java:1066)

我有要插入值的DAO对象和控制器：

控制器：

  @PostMapping( value = "/newBook",consumes = {MediaType.MULTIPART_FORM_DATA_VALUE})
public String add(@ModelAttribute("book") @Valid Book book, HttpServletResponse response, HttpServletRequest request,@RequestParam(value = "photo", required = false) List<MultipartFile> photos, @RequestParam(value = "valute",required = false) String valute,BindingResult result) {
    if (result.hasErrors()) {
        return "addBook";}

    List<entity.photos> list = new ArrayList<>();
    for (MultipartFile photo : photos) {
        File file =null;
        if (!photo.isEmpty()) {
            try {
                validateImg(photo);
                file = new File(context.getRealPath("/uploadFile/" + photo.getOriginalFilename()));
                Logger.getAnonymousLogger().info("THE PATH IS " + file.getAbsolutePath());
                FileUtils.copyInputStreamToFile(photo.getInputStream(), file);
                file.createNewFile();
            } catch (IOException ex) {
                result.reject("uk_UA", "Поганий тип");
                return "addBook";
            }
        }
        if (file != null) {
            photos ph = new photos(photo.getOriginalFilename());
            StringBuilder builder = new StringBuilder();
            builder.append(file.getAbsolutePath());
            Logger.getAnonymousLogger().info("SOMETHING HAS BROKEN IN LOGGING FILE");
            System.out.println("INSIDE ADD METHOD ");
            list.add(ph);

        } else list.add(new photos(""));
    }
    book.getPhotosList().addAll(list);
    service.add(book);

    return "redirect:/books";
}

DAO：

   public void add(Book user) {
        currentSession().save(user);
}

Answer 1

很可能您尚未将“照片”中的后向引用设置为“书”，然后通过“照片”集合将“书”中的持久/合并操作进行级联。将元素添加到集合时，需要保持关系的双方。例如：

from kivy.app import App
from kivy.lang import Builder
from kivy.uix.boxlayout import BoxLayout
from kivy.uix.dropdown import DropDown
from kivy.uix.button import Button

kv = """
<CustomDropdown>:
    size_hint_y: None
    pos_hint: {"top": 1}
    height: 56.0
    orientation: "horizontal"

    TextInput:
        id: txt_input
        size_hint_x: 0.5

    Button:
        id: show_drop
        size_hint_x: 0.2
        text: "drop"
        on_release: root.show_dropdown()
    Button:
        id: submit_btn
        size_hint_x: 0.3
        text: "Submit"
        on_press: root.validate_txt()
"""


class CustomDropdown(BoxLayout):
    def __init__(self, **kwargs):
        super().__init__(**kwargs)

        self.dropdown = DropDown()
        self.fakeValues = ["First", "Second", "Third"]
        for val in self.fakeValues:
            btn = Button(text=val, size_hint=[0.5, None])
            btn.height = 56.0
            btn.bind(on_press=self.change_value)
            self.dropdown.add_widget(btn)

    def change_value(self, *args):
        self.ids.txt_input.text = args[0].text
        self.hide_dropdown()

    def add_options(self, *args):
        btn = Button(text=args[0], size_hint=[0.5, None])
        btn.height = 56.0
        btn.bind(on_press=self.change_value)
        self.dropdown.add_widget(btn)


    def validate_txt(self, *args):
        curText = self.ids.txt_input.text
        if ((curText in self.fakeValues) or (curText == None) or (curText == "")):
            return
        self.fakeValues.append(curText)
        self.add_options(curText)
        self.hide_dropdown()

    def hide_dropdown(self):
        self.dropdown.dismiss()

    def show_dropdown(self, *args):
        if self.dropdown.parent:
            self.hide_dropdown()
        else:
            self.dropdown.open(self.ids.txt_input)

class TestApp(App):
    def build(self):
        Builder.load_string(kv)
        return CustomDropdown()

TestApp().run()

java.sql.SQLIntegrityConstraintViolationException：列'library_idlibrary'不能为null

1 个答案: