【发布时间】：2016-01-15 17:00:11
【问题描述】：
我在数据库中有两个表：Book 和 Category。现在我想创建一个页面，用户可以在其中将书籍添加到 Book 表中，但要从 Category 表中选择适当的类别。
我可以将 book 添加到表格中，但我无法在 Book 表格中保存价值 category。
如您所见，Book 表中的 category 是 外键，category_id 来自 Category 表格。
这里是模型类：
图书模型
@Entity
@Table(name = "book")
@XmlRootElement
@NamedQueries({
@NamedQuery(name = "Book.findAll", query = "SELECT b FROM Book b"),
@NamedQuery(name = "Book.findByBookId", query = "SELECT b FROM Book b WHERE b.bookId = :bookId")})
public class Book implements Serializable {
private static final long serialVersionUID = 1L;
@Id
@GeneratedValue(strategy = GenerationType.IDENTITY)
@Basic(optional = false)
@Column(name = "book_id")
private Integer bookId;
@Basic(optional = false)
@NotNull
@Lob
@Size(min = 1, max = 65535)
@Column(name = "name")
private String name;
@Lob
@Size(max = 65535)
@Column(name = "description")
private String description;
@JoinColumn(name = "category", referencedColumnName = "category_id")
@ManyToOne
private Category category;
public Book() {
}
public Book(Integer bookId) {
this.bookId = bookId;
}
public Book(Integer bookId, String name) {
this.bookId = bookId;
this.name = name;
}
public Integer getBookId() {
return bookId;
}
public void setBookId(Integer bookId) {
this.bookId = bookId;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public String getDescription() {
return description;
}
public void setDescription(String description) {
this.description = description;
}
public Category getCategory() {
return category;
}
public void setCategory(Category category) {
this.category = category;
}
@Override
public int hashCode() {
int hash = 0;
hash += (bookId != null ? bookId.hashCode() : 0);
return hash;
}
@Override
public boolean equals(Object object) {
// TODO: Warning - this method won't work in the case the id fields are not set
if (!(object instanceof Book)) {
return false;
}
Book other = (Book) object;
if ((this.bookId == null && other.bookId != null) || (this.bookId != null && !this.bookId.equals(other.bookId))) {
return false;
}
return true;
}
@Override
public String toString() {
return "com.biblioteka.app.domen.Book[ bookId=" + bookId + " ]";
}
}
类别模型
@Entity
@Table(name = "category")
@XmlRootElement
@NamedQueries({
@NamedQuery(name = "Category.findAll", query = "SELECT c FROM Category c"),
@NamedQuery(name = "Category.findByCategoryId", query = "SELECT c FROM Category c WHERE c.categoryId = :categoryId")})
public class Category implements Serializable {
private static final long serialVersionUID = 1L;
@Id
@GeneratedValue(strategy = GenerationType.IDENTITY)
@Basic(optional = false)
@Column(name = "category_id")
private Integer categoryId;
@Basic(optional = false)
@NotNull
@Lob
@Size(min = 1, max = 65535)
@Column(name = "name")
private String name;
@Lob
@Size(max = 65535)
@Column(name = "description")
private String description;
@OneToMany(mappedBy = "category")
private Collection<Book> bookCollection;
public Category() {
}
public Category(Integer categoryId) {
this.categoryId = categoryId;
}
public Category(Integer categoryId, String name) {
this.categoryId = categoryId;
this.name = name;
}
public Integer getCategoryId() {
return categoryId;
}
public void setCategoryId(Integer categoryId) {
this.categoryId = categoryId;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public String getDescription() {
return description;
}
public void setDescription(String description) {
this.description = description;
}
@XmlTransient
public Collection<Book> getBookCollection() {
return bookCollection;
}
public void setBookCollection(Collection<Book> bookCollection) {
this.bookCollection = bookCollection;
}
@Override
public int hashCode() {
int hash = 0;
hash += (categoryId != null ? categoryId.hashCode() : 0);
return hash;
}
@Override
public boolean equals(Object object) {
// TODO: Warning - this method won't work in the case the id fields are not set
if (!(object instanceof Category)) {
return false;
}
Category other = (Category) object;
if ((this.categoryId == null && other.categoryId != null) || (this.categoryId != null && !this.categoryId.equals(other.categoryId))) {
return false;
}
return true;
}
@Override
public String toString() {
return "com.biblioteka.app.domen.Category[ categoryId=" + categoryId + " ]";
}
}
现在我有 JSF 页面，我可以在其中将书籍添加到数据库中。我有将类别加载到其中的下拉列表。用户应该选择一个类别并将书籍保存到表格中。
这是来自 JSF addBook 页面的代码。
<p:layoutUnit position="center">
<h:form>
<p:inputText value="#{bookBean.name}" a:placeholder="Ime knjige"></p:inputText><br/>
<p:inputText value="#{bookBean.description}" a:placeholder="Opis knjige"></p:inputText><br/>
<p:selectOneMenu value="#{bookBean.category}">
<f:selectItems value="#{categoryBean.allCategories}" var="c"
itemLabel="#{c.name}" itemValue="#{c.categoryId}"/>
</p:selectOneMenu>
<b/><b/>
<p:commandButton value="Dodaj knjigu" action="#{bookBean.addBook()}"/>
</h:form>
</p:layoutUnit>
如您所见，我使用 selectOneMenu 和值 bookBean.category 然后我不确定我需要在 selectItems 中设置什么值>.
这是BookBean代码：
@ManagedBean
@ApplicationScoped
public class BookBean {
String name;
String description;
int categoryId;
Category category;
@Inject
public BookEJB bookEJB;
public void addBook(){
Book book = new Book();
book.setName(name);
book.setDescription(description);
book.setCategory(category);
bookEJB.addBook(book);
}
public List<Book> getAllBooks(){
return bookEJB.getAll();
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public String getDescription() {
return description;
}
public void setDescription(String description) {
this.description = description;
}
public int getCategoryId() {
return categoryId;
}
public void setCategoryId(int categoryId) {
this.categoryId = categoryId;
}
public Category getCategory() {
return category;
}
public void setCategory(Category category) {
this.category = category;
}
public BookEJB getBookEJB() {
return bookEJB;
}
public void setBookEJB(BookEJB bookEJB) {
this.bookEJB = bookEJB;
}
}
【问题讨论】：
标签： jsf jsf-2 selectonemenu