从数据库返回值时的数字格式异常（JPA） [英] Number format exception when returning values from database(JPA)

问题描述

我想用数据库中的一些值填充一个简单的h：datatable标记。但我得到一个例外，我无法找到原因：

I want to fill a simple h:datatable tag with some values from a database. But i get an exception and i cant find what is the reason:

java.lang.NumberFormatException：对于输入字符串：url

java.lang.NumberFormatException: For input string: "url"

这是我创建数据表的方式：

This is how i create the datatable:

<h:form>        
    <h:dataTable value="#{managementBB.retrieveRecords()}" var="record">
    <h:column>
        <f:facet name="header">URL</f:facet>
        #{record.url}
    </h:column>
    <h:column>
        <f:facet name="header">Submition date</f:facet>
        #{record.submitionDate}
    </h:column>
    <h:column>
        <f:facet name="header">Unacceptable</f:facet>
        #{record.unnaceptableContent}
    </h:column>
    <h:column>
        <f:facet name="header">Option</f:facet>
        Something
    </h:column>
    </h:dataTable>
</h:form>

这是此页面背后的支持bean：

This is the backing bean behind this page:

@Named("managementBB")
@SessionScoped
public class ManagementBB implements Serializable{

    @EJB
    private ILinkManagerEJB linkManagerEJB;

    public List<Record> retrieveRecords() {     
            return linkManagerEJB.retrieveRecords();
    }
}

这是访问数据库以获取data：

This is the EJB that accesses the database to get the data:

@Stateless(name = "ejbs/LinkManagerEJB")
public class LinkManagerEJB implements ILinkManagerEJB {

    @PersistenceContext
    private EntityManager entityManager;

    public List<Record> retrieveRecords() {
        Query allRecords = entityManager.createNamedQuery("allrecordinfo");      
        return (List<Record>) allRecords.getResultList();
    }
}

最后这是代表一行的JPA实体在数据库中：

And finally this is the JPA entity that represents a row in the database:

@Entity
@NamedQueries({@NamedQuery(name = "allrecordinfo",
   query = "SELECT r.url, r.submitionDate, r.unnaceptableContent FROM Record r")})
public class Record {

    @Id
    @GeneratedValue
    private long id;
    @Column(nullable = false)
    private String url;
    @Column(nullable = false)
    private String submitionDate;
    @Column(nullable = false)
    private boolean unnaceptableContent;

    //Get set methods ...
}

你看，它看起来很简单，我以前做过这个，但现在我很困惑，我不知道为什么不工作。你能帮我找到我的错误吗？

As you see it looks simple, and I've done this before but now I am confused, I don't know why is not working. Could you help me find my error?

注意：我非常有信心查询语法没问题（我在eclipse的剪贴簿中测试过）

Note: I am pretty confident that the query syntax is ok (I tested it in eclipse's scrapbook)

推荐答案

查询不正确。

@NamedQueries({ @NamedQuery(name = "allrecordinfo", query = "SELECT r FROM Record r") })
@Entity
public class Record {
}

这篇关于从数据库返回值时的数字格式异常（JPA）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！