在保持之前从JPA OneToManyList中删除项目

Question

这是关于JSF + JPA应用程序。

Bill和BillItem是两个实体，与JPA应用程序中的cascadeType = all具有双边OneToMany关系。

当使用单击新Bill时，将创建一个新的Bill对象。然后，用户填写BillItem的属性，如名称和数量，然后单击“添加到帐单”按钮，以便将BillItem添加到Bill对象的BillItem列表中。使用链接到bill.billItems的数据表更新用户界面。

在帐单中添加一个或多个billItem后，用户单击持有帐单对象的结算按钮。

问题是无法从列表中删除billItem。始终删除第一个项目。如何从列表中获取所需的billItem？

条例实体守则

@Entity
public class Bill implements Serializable {

    @OneToMany(mappedBy = "bill", cascade = CascadeType.ALL, fetch = FetchType.EAGER)
    List<BillItem> billItems = new ArrayList<>();

...
..

}

BillItem实体的代码

@Entity
public class BillItem implements Serializable {

    @ManyToOne
    Bill bill;

....
...


@Override
public boolean equals(Object object) {

    if (!(object instanceof BillItem)) {
        return false;
    }
    BillItem other = (BillItem) object;
    if ((this.id == null && other.id != null) || (this.id != null && !this.id.equals(other.id))) {
        return false;
    }
    return true;
}
}

JSF Managed Bean的代码

@Named
@SessionScoped
public class SaleController implements Serializable {

    private BilledBill bill;
    BillItem billItem;

    public void removeItem(){
        if(removingItem==null){
            UtilityController.addErrorMessage("Select one to remove");
            return;
        }
        getBill().getBillItems().remove(removingItem);
    }

    public String newSaleBill() {
        fillAvailableStocks();
        listBillsToSettle();
        clearBill();
        clearBillItem();
        printPreview = false;
        bill = null;
        return "sale";
    }

    public void settle() {
....
        saveBill();
        UtilityController.addSuccessMessage("Successfully Billed");
    }


    public void addItem() {
......
        getBill().getBillItems().add(billItem);
        calTotal();
        clearBillItem();
    }




    public void saveBill() {
        bill.setBillType(BillType.SaleToCustomer);
        getBill().setInstitution(getSessionController().getInstitution());
        getBill().setDepartment(getSessionController().getDepartment());
        getBill().setStaff(getSessionController().getLoggedUser().getStaff());

        getBill().setDeptId(getBillNumberBean().departmentBillNumberGenerator(getSessionController().getDepartment(), BillType.SaleToCustomer, BillNumberSuffix.SB));
        getBill().setInsId(getBillNumberBean().institutionBillNumberGenerator(getSessionController().getInstitution(), BillType.SaleToCustomer, BillNumberSuffix.SB));
        getBill().setRepId(getBillNumberBean().institutionBillNumberGenerator(getSessionController().getLoggedUser().getStaff(), BillType.SaleToCustomer, BillNumberSuffix.SB));
        getBill().setToInstitution(getSessionController().getInstitution());
        getBill().setToDepartment(getSessionController().getDepartment());
        getBill().setCreatedAt(new Date());


        getBill().setBillDate(Calendar.getInstance().getTime());
        getBill().setCreater(getSessionController().getLoggedUser());
        getBillFacade().create(getBill());
    }


    public BilledBill getBill() {
        if (bill == null) {
            bill = new BilledBill();
            getBillFacade().create(bill);

        }
        return bill;
    }


    public BillItem getBillItem() {
        if (billItem == null) {
            billItem = new BillItem();
        }
        return billItem;
    }

    public void setBillItem(BillItem BillItem) {
        this.billItem = BillItem;
    }


    public BillItem getRemovingItem() {
        return removingItem;
    }

    public void setRemovingItem(BillItem removingItem) {
        this.removingItem = removingItem;
    }



}

JSF页面

            <h:panelGrid columns="5">
                <h:outputLabel value="Select Item"/>
                <h:outputLabel value="Qty (kg)"/>
                <h:outputLabel value="Rate"/>
                <h:outputLabel value="Value"/>
                <h:outputLabel value=""/>
                <p:selectOneMenu id="acItem" converter="stockCon" value="#{saleController.billItem.stock}" var="vt"   >
                    <f:selectItems value="#{saleController.availableStock}" var="ast" itemValue="#{ast}" itemLabel="#{ast.itemBatch.item.name}" ></f:selectItems>
                    <p:column >
                        <h:outputLabel value="#{vt.itemBatch.item.name}" ></h:outputLabel>
                    </p:column>
                    <p:column >
                        <h:outputLabel value="#{vt.stock}" ></h:outputLabel>
                    </p:column>
                </p:selectOneMenu>
                <p:inputText id="txtQty" value="#{saleController.billItem.qty}"   styleClass="normalNoBox" >
                    <f:ajax event="blur" execute="acItem txtQty " render="" listener="#{saleController.calValueFromRate()}"></f:ajax>
                </p:inputText>  
                <p:inputText id="txtRate" value="#{saleController.billItem.netRate}"   styleClass="normalNoBox" >
                    <f:ajax event="blur" execute="acItem txtQty txtRate" render="lblVal" listener="#{saleController.calValueFromRate()}" ></f:ajax>
                </p:inputText>
                <h:outputLabel id="lblVal" value="#{saleController.billItem.netValue}"  styleClass="normalNoBox" ></h:outputLabel>
                <p:commandButton value="Add Item" action="#{saleController.addItem}" ajax="false" />
            </h:panelGrid>
            <p:panelGrid columns="2">                        
            </p:panelGrid>
        </h:panelGrid>

        <p:dataTable var="ph" value="#{saleController.bill.billItems}" id="itemList">  
            <f:facet name="header">  
                <h:outputLabel value="Sale Items" ></h:outputLabel>
            </f:facet>  
            <p:column headerText="Item Name" style="width:30%">  
                <h:outputLabel id="item" value="#{ph.item.name}"  >
                </h:outputLabel>
            </p:column>  
            <p:column headerText="Qty (kg)" style="width:20%">                     
                <h:outputLabel id="qty" value="#{ph.qty}"  >
                </h:outputLabel>
            </p:column>  
            <p:column headerText="Rate" style="width:20%">                     
                <h:outputLabel id="itemRate" value="#{ph.grossRate}"  >
                </h:outputLabel>
            </p:column>  
            <p:column headerText="Value" style="width:20%">                     
                <h:outputLabel id="itemVal" value="#{ph.grossValue}"  >
                </h:outputLabel>
            </p:column>  
             <p:column headerText="Remove" style="width:20%">                     
                 <h:commandButton value="Remove" action="#{saleController.removeItem()}" >
                     <f:setPropertyActionListener target="#{saleController.removingItem}" value="#{ph}" ></f:setPropertyActionListener>
                 </h:commandButton>
            </p:column>  

        </p:dataTable>  
    </p:panel>