Question

public List findCatalog() {
    Query query = getEntityManager().createQuery("SELECT pc.productCatalog, p.name, p.product FROM ProductCatalog pc JOIN pc.products p");
    return query.getResultList();
}

Hello, with such query my application compiles okay. But when i open the page where this query is executed i get the following error:

org.apache.jasper.JasperException: java.lang.NumberFormatException: For input string: “productCatalog”

The productCatalog is my primary key, but same happens when i just include the name column

exception
org.apache.jasper.JasperException: java.lang.NumberFormatException: For input string: “name”
root cause

java.lang.NumberFormatException: For input string: “name”

If i don’t make the join in my query then the results from 1 table are printed okay.
I’m clueless for now where the problem could be, i have read Pro JPA 2 book, official java EE 6 tutorial, googled alot.
The tables design is ManyToMany. I have product table, *product_catalog* table and the binding table *product_product_catalog. I don’t have foreign keys in the binding table.
I have created the entity and facade classes with the NetBeans EclipseLink wizard.

Here is how i mapped on my ProductCatalog class many to many relationship

@ManyToMany
    @JoinTable(name = "product_product_catalog",
    joinColumns = {
        @JoinColumn(name = "product_catalog")
    },
    inverseJoinColumns = {
        @JoinColumn(name = "product")
    })
    private Collection<Product> products;

product and product_catalog are the primary keys for corresponding tables.
Now i have no idea where i could be wrong, perhaps is the mapping wrong? Though many examples which i have seen, have the same mapping implementation, but in their tables they have foreign keys, could that be an issue?
Moreover as i said if i don’t join second table, everything works well.

Here is my servlet with initializing that method getServletContext().setAttribute("productCatalog", productCatalogFacade.findCatalog());

And here is my JSP page fragment of that

<table>
            <c:forEach var="list" items="${productCatalog}" varStatus="iter">
                <tr>
                    <td>${list.productCatalog}</td>
                    <td>${list.product}</td>
                    <td>${list.name}</td>
                </tr>
            </c:forEach>
        </table>

And here is my native SQL query what i’m trying to achieve

SELECT PPC.product_product_catalog, PPC.product_catalog, PPC.product, P.name, PC.name AS  "catalog name", P.code, P.description, P.price, P.producer
FROM product_catalog PC
INNER JOIN product_product_catalog PPC ON PC.product_catalog = PPC.product_catalog
INNER JOIN product P ON P.product = PPC.product

As my last piece of code here is the output which glassfish produces when i go to that page where the query is executed:

WARNING: StandardWrapperValve[jsp]: PWC1406: Servlet.service() for servlet jsp threw exception
java.lang.NumberFormatException: For input string: "productCatalog"
        at java.lang.NumberFormatException.forInputString(NumberFormatException.java:48)
        at java.lang.Integer.parseInt(Integer.java:449)
        at java.lang.Integer.parseInt(Integer.java:499)
        at javax.el.ArrayELResolver.toInteger(ArrayELResolver.java:375)
        at javax.el.ArrayELResolver.getValue(ArrayELResolver.java:195)
        at javax.el.CompositeELResolver.getValue(CompositeELResolver.java:175)
        at com.sun.el.parser.AstValue.getValue(AstValue.java:116)
        at com.sun.el.parser.AstValue.getValue(AstValue.java:163)
        at com.sun.el.ValueExpressionImpl.getValue(ValueExpressionImpl.java:219)
        at org.apache.jasper.runtime.PageContextImpl.evaluateExpression(PageContextImpl.java:1007)
        at org.apache.jsp.index_jsp._jspx_meth_c_forEach_0(index_jsp.java from :206)
        at org.apache.jsp.index_jsp._jspService(index_jsp.java from :137)
        at org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:109)
        at javax.servlet.http.HttpServlet.service(HttpServlet.java:847)
        at org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:406)
        at org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:483)
        at org.apache.jasper.servlet.JspServlet.service(JspServlet.java:373)
        at javax.servlet.http.HttpServlet.service(HttpServlet.java:847)
        at org.apache.catalina.core.StandardWrapper.service(StandardWrapper.java:1523)
        at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:279)
        at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:188)
        at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:641)
        at com.sun.enterprise.web.WebPipeline.invoke(WebPipeline.java:97)
        at com.sun.enterprise.web.PESessionLockingStandardPipeline.invoke(PESessionLockingStandardPipeline.java:85)
        at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:185)
        at org.apache.catalina.connector.CoyoteAdapter.doService(CoyoteAdapter.java:325)
        at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:226)
        at com.sun.enterprise.v3.services.impl.ContainerMapper.service(ContainerMapper.java:165)
        at com.sun.grizzly.http.ProcessorTask.invokeAdapter(ProcessorTask.java:791)
        at com.sun.grizzly.http.ProcessorTask.doProcess(ProcessorTask.java:693)
        at com.sun.grizzly.http.ProcessorTask.process(ProcessorTask.java:954)
        at com.sun.grizzly.http.DefaultProtocolFilter.execute(DefaultProtocolFilter.java:170)
        at com.sun.grizzly.DefaultProtocolChain.executeProtocolFilter(DefaultProtocolChain.java:135)
        at com.sun.grizzly.DefaultProtocolChain.execute(DefaultProtocolChain.java:102)
        at com.sun.grizzly.DefaultProtocolChain.execute(DefaultProtocolChain.java:88)
        at com.sun.grizzly.http.HttpProtocolChain.execute(HttpProtocolChain.java:76)
        at com.sun.grizzly.ProtocolChainContextTask.doCall(ProtocolChainContextTask.java:53)
        at com.sun.grizzly.SelectionKeyContextTask.call(SelectionKeyContextTask.java:57)
        at com.sun.grizzly.ContextTask.run(ContextTask.java:69)
        at com.sun.grizzly.util.AbstractThreadPool$Worker.doWork(AbstractThreadPool.java:330)
        at com.sun.grizzly.util.AbstractThreadPool$Worker.run(AbstractThreadPool.java:309)
        at java.lang.Thread.run(Thread.java:619)

Answer 1

When you execute a request with many variables in SELECT clause, such as

SELECT pc.productCatalog, p.name, p.product ...

each row of result is returned in form of Object[], so you need to use numeric indexes to access its elements:

<c:forEach var="list" items="${productCatalog}" varStatus="iter"><tr>
    <td>${list[0]}</td> 
    <td>${list[2]}</td>
    <td>${list[1]}</td>
</tr></c:forEach>