Fatal编程技术网
  • jsf/
  • 获取JSF下拉列表值并保存到数据库

获取JSF下拉列表值并保存到数据库

jsf jsf-2

获取JSF下拉列表值并保存到数据库,jsf,jsf-2,selectonemenu,Jsf,Jsf 2,Selectonemenu,数据库中有两个表：Book和Category。现在我想创建一个页面，用户可以在其中向图书表中添加图书，但需要从分类表中选择合适的分类 我可以将书籍添加到表中，但无法将值类别保存到书籍表中 [ 正如您可以从图书中看到的类别表是外键和类别id来自类别表 以下是模型类： 图书型号 @Entity @Table(name = "book") @XmlRootElement @NamedQueries({ @NamedQuery(name = "Book.findAll", query = "SELEC

数据库中有两个表：Book和Category。现在我想创建一个页面，用户可以在其中向图书表中添加图书，但需要从分类表中选择合适的分类

我可以将书籍添加到表中，但无法将值类别保存到书籍表中

[

正如您可以从图书中看到的类别表是外键和类别id来自类别表

以下是模型类：

图书型号

@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 + " ]";
}

 @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 + " ]";
}
}

类别模型

@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 + " ]";
}

 @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 + " ]";
}

@实体
@表（name=“category”）
@XmlRootElement
@命名查询({
@NamedQuery（name=“Category.findAll”，query=“从类别c中选择c”），
@NamedQuery（name=“Category.findByCategoryId”，query=“从c类中选择c，其中c.categoryId=：categoryId”））
公共类类别实现可序列化{
私有静态最终长serialVersionUID=1L；
@身份证
@GeneratedValue（策略=GenerationType.IDENTITY）
@基本（可选=假）
@列（name=“category\u id”）
私有整数类别ID；
@基本（可选=假）
@NotNull
@高球
@尺寸（最小值=1，最大值=65535）
@列（name=“name”）
私有字符串名称；
@高球
@尺寸（最大值=65535）
@列（name=“description”）
私有字符串描述；
@OneToMany（mappedBy=“类别”）
私人藏书；
公共类别（）{
}
公共类别（整数类别ID）{
this.categoryId=categoryId；
}
公共类别（整数类别ID，字符串名称）{
this.categoryId=categoryId；
this.name=名称；
}
公共整数getCategoryId（）{
返回类别ID；
}
public void setCategoryId（整型categoryId）{
this.categoryId=categoryId；
}
公共字符串getName（）{
返回名称；
}
公共void集合名（字符串名）{
this.name=名称；
}
公共字符串getDescription（）{
返回说明；
}
公共void集合描述（字符串描述）{
this.description=描述；
}
@XmlTransient
公共集合getBookCollection（）{
还书回收；
}
公共作废setBookCollection（集合账簿集合）{
this.bookCollection=bookCollection；
}
@凌驾
公共int hashCode（）{
int hash=0；
hash+=（categoryId！=null？categoryId.hashCode（）：0）；
返回散列；
}
@凌驾
公共布尔等于（对象）{
//TODO:警告-如果未设置id字段，此方法将不起作用
如果（！（类别的对象实例））{
返回false；
}
类别其他=（类别）对象；
如果（（this.categoryId==null&&other.categoryId！=null）| |（this.categoryId！=null&&other.categoryId.equals（other.categoryId）））{
返回false；
}
返回true；
}
@凌驾
公共字符串toString（）{
返回“com.biblioteka.app.domen.Category[categoryId=“+categoryId+””；
}
}

现在我有了JSF页面，在这里我将书籍添加到数据库中。我有下拉列表，可以将类别加载到其中。用户应该选择一个类别并将书籍保存到表中

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，我使用带有值的selectOneMenubookBean.category，然后我不确定需要在selectItems中设置哪些值

  <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>
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;
}

@ManagedBean
@适用范围
公共类书豆{
字符串名；
字符串描述；
int分类；
类别；
@注入
公共图书；
公共无效地址簿（）{
书=新书（）；
book.setName（名称）；
书.集说明（说明）；
图书分类（分类）；
bookEJB.addBook（book）；
}
公共列表getAllBooks（）{
返回bookEJB.getAll（）；
}
公共字符串getName（）{
返回名称；
}
公共void集合名（字符串名）{
this.name=名称；
}
公共字符串getDescription（）{
返回说明；
}
公共void集合描述（字符串描述）{
this.description=描述；
}
public int getCategoryId（）{
返回类别ID；
}
public void setCategoryId（int categoryId）{
this.categoryId=categoryId；
}
公共类别getCategory（）{
退货类别；
}
公共无效集合类别（类别）{
this.category=类别；
}
public BookEJB getBookEJB（）{
返回bookEJB；
}
公共无效设置BookEJB（BookEJB BookEJB）{
this.bookEJB=bookEJB；
}
}试试这个：

 <f:selectItems value="#{categoryBean.allCategories}" var="c"
                               itemLabel="#{c.name}" itemValue="#{c}"/>
列出的项目名称将是类别名称，类别将分配给bookBean.category，这可以设置为book category并持久化

希望这能有所帮助。

我试过这个，但不知怎么的它不起作用。你还有其他想法吗？下次，不要说“它不起作用”，谷歌在错误消息上。错误消息就是答案。这只是找到解释的问题。你可以找到@BalusC谢谢，这很有帮助。现在我得到了NPE，因为转换器中的ManagedBean似乎总是空的。我如何解决这个问题？