使用列表和复选框的Spring MVC数据绑定 [英] Spring MVC databinding using lists and checkboxes
问题描述
我知道有关此问题的问题已经提出,但是我发现的答案都没有解决我的问题.
I know questions on this matter have been asked already, but none of the answers I found solved my problem.
我的数据库上有多对多的关系.我正在使用JPA和Hibernate创建和更改表.这是我的模型类:
I have a many-to-many relantionship on my database. I'm using JPA and Hibernate to create and alter my tables. Here are my model classes:
Book.java
Book.java
@Entity
@Table(name="tb_books")
public class Book implements Serializable {
@Id
@GeneratedValue(strategy = GenerationType.IDENTITY)
@Column(name = "id", updatable = false, nullable = false, insertable = false)
private Integer id;
@Column(name = "title", nullable = false, length = 255)
private String title;
@Column(name = "author", nullable = false, length = 255)
private String author;
@ManyToMany(cascade = {CascadeType.PERSIST, CascadeType.MERGE}, fetch = FetchType.EAGER)
@JoinTable(name = "book_tag",
joinColumns = { @JoinColumn(name = "fk_book") },
inverseJoinColumns = { @JoinColumn(name = "fk_tag") })
private List<Tag> tags;
//getters, setters, equals and hash methods...
}
Tag.java
@Entity
@Table(name="tb_tags")
public class Tag implements Serializable {
@Id
@GeneratedValue(strategy = GenerationType.IDENTITY)
@Column(name = "id", updatable = false, nullable = false)
private Integer id;
@Column(name = "description", nullable = false, length = 255)
private String description;
//getters, setters, equals and hash methods...
}
我正在尝试使用Spring MVC使用来自JSP的数据在book_tag表中进行插入和更新.这是我的控制器和插入页面:
I'm trying to make insertions and updates on my book_tag table with the data comming from a JSP using Spring MVC. Here is my controller and insertion page:
BookController.java
BookController.java
@Controller
@RequestMapping(value = "/book")
public class BookController {
@Autowired
private BookService bookService;
/*
Controller method that gets us to the adding book page.
*/
@RequestMapping(value = "/add", method = RequestMethod.GET)
public ModelAndView addBookPage() {
List<Tag> tags = tagService.getTags(); //all tags from the database
ModelAndView modelAndView = new ModelAndView("form-book");
modelAndView.addObject("book", new Book());
modelAndView.addObject("tags", tags);
return modelAndView;
}
@RequestMapping(value = "/add", method = RequestMethod.POST)
public ModelAndView addBookProcess(@ModelAttribute Book book) {
bookService.addBook(book);
return new ModelAndView("redirect:/book/add");
}
//...
}
form-book.jsp
form-book.jsp
<form:form method="POST" modelAttribute="book" action="${pageContext.request.contextPath}/book/add.html">
<table>
<tbody>
<tr>
<td>Title:</td>
<td><form:input path="title" autocomplete="off" /></td>
</tr>
<tr>
<td>Author:</td>
<td><form:input path="author" autocomplete="off" /></td>
</tr>
<tr>
<td colspan="2">
<form:checkboxes path="tags"
items="${tags}"
itemLabel="description"
itemValue="id"/>
</td>
</tr>
<tr>
<td><input type="submit" value="Add" /></td>
<td><input type="button" onclick="location.href = '${pageContext.request.contextPath}/index'" value="Cancel"/></td>
</tr>
</tbody>
</table>
</form:form>
一切正常,除非我尝试选择一个或多个复选框更新或插入书籍.当我尝试这样做时,我会得到一个错误请求"页面,我想是因为我在处理数据绑定时做错了什么.
Everything is working fine, except when I try to update or insert books with one or more checkboxes selected. When I try to do so, I just get a "Bad Request" page, I imagine because of something wrong I'm doing concerning databinding.
这是我应该处理这种情况的方式吗?有没有更好的办法?我在做什么错了?
Is this the way I'm supposed to handle this situation? Is there a better way? What am I doing wrong?
推荐答案
很明显,从复选框发出的列表实际上是一个字符串数组,无法将其转换为定义模型类的标签列表.
Apparently, the List comming from the checkbox was actually an array of Strings, which could not be converted to a List of Tags, as defined the model classes.
我通过创建一个自定义的PropertyEditor解决了我的问题,这使我可以将复选框与标签列表绑定.
I solved my problem by creating a custom PropertyEditor, which would allow me to bind the checkboxes with the list of tags.
public class TagPropertyEditor extends PropertyEditorSupport {
private TagService tagService;
public TagPropertyEditor(TagService tagService){
this.tagService = tagService;
}
@Override
public String getAsText() {
return ((Tag) getValue()).getId().toString();
}
@Override
public void setAsText(String incomingId) throws IllegalArgumentException {
Tag tag = tagService.getTag(Integer.valueOf(incomingId));
setValue(tag);
}
}
然后在我的BookController上注册:
And then registering on my BookController:
//...
@InitBinder
public void initBinder(WebDataBinder binder){
binder.registerCustomEditor(Tag.class, new TagPropertyEditor(tagService));
}
这是我的JSP上的checboxes标记:
And this is the checboxes tag on my JSP:
<form:checkboxes path="tags"
items="${tags}"
itemLabel="description"
itemValue="id"/>
这篇关于使用列表和复选框的Spring MVC数据绑定的文章就介绍到这了,希望我们推荐的答案对大家有所帮助,也希望大家多多支持IT屋!