你如何访问节点列表中的节点，有时只会出现c# xml

Question

    <OrderFeed>
<Order id="1">
    <BillingInformation>
        <Name>Bruce Ganek</Name>
        <Address>99 Main Street</Address>
        <City>Cranston</City>
        <State>RI</State>
        <ZipCode>02910</ZipCode>
    </BillingInformation>
    <ShippingInformation>
        <Name>Governor Chafee</Name>
        <Address>82 Smith St # 115</Address>
        <City>Providence</City>
        <State>RI</State>
        <ZipCode>02903-1121</ZipCode>
    </ShippingInformation>
    <Items>
        <Item>
            <PartNo>JETSWEATER</PartNo>
            <Description>N.Y. Jets Sweatshirt</Description>
            <UnitPrice>10.50</UnitPrice>
            <Quantity>2</Quantity>
            <TotalCost>21.00</TotalCost>
            <CustomerOptions>
                <Size>M</Size>
                <Color>Green</Color>
            </CustomerOptions>
        </Item>
        <Item>
            <PartNo>JETSWEATER</PartNo>
            <Description>N.Y. Jets Sweatshirt</Description>
            <UnitPrice>7.50</UnitPrice>
            <Quantity>3</Quantity>
            <TotalCost>22.50</TotalCost>

            <CustomerOptions>
                <Size>S</Size>
                <Color>White</Color>
            </CustomerOptions>
        </Item>
        <Item>
            <PartNo>JETSFLASHLIGHT</PartNo>
            <Description>N.Y. Jets Flashlight</Description>
            <UnitPrice>5.00</UnitPrice>
            <Quantity>1</Quantity>
            <TotalCost>5.00</TotalCost>

            <CustomerOptions/>

        </Item>

    </Items>
</Order>
<Order id="2">
    <BillingInformation>
        <Name>Walt Disney</Name>
        <Address>DisneyWorld Hotel</Address>
        <City>Orlando</City>
        <State>FL</State>
        <ZipCode>32801</ZipCode>
    </BillingInformation>
    <ShippingInformation>
        <Name>Walt Disney</Name>
        <Address>DisneyWorld Hotel</Address>
        <City>Orlando</City>
        <State>FL</State>
        <ZipCode>32801</ZipCode>
    </ShippingInformation>
    <Items>
        <Item>
            <PartNo>JETSWEATER</PartNo>
            <Description>N.Y. Jets Sweatshirt</Description>
            <UnitPrice>10.50</UnitPrice>
            <Quantity>2</Quantity>
            <TotalCost>21.00</TotalCost>
            <CustomerOptions>
                <Size>M</Size>
                <Color>Green</Color>
            </CustomerOptions>
        </Item>
        <Item>
            <PartNo>JETSWEATER</PartNo>
            <Description>N.Y. Jets Sweatshirt</Description>
            <UnitPrice>7.50</UnitPrice>
            <Quantity>3</Quantity>
            <TotalCost>22.50</TotalCost>

            <CustomerOptions>
                <Size>S</Size>
                <Color>White</Color>
            </CustomerOptions>
        </Item>
        <Item>
            <PartNo>JETSFLAG</PartNo>
            <Description>N.Y. Jets Flag for display</Description>
            <UnitPrice>5.00</UnitPrice>
            <Quantity>1</Quantity>
            <TotalCost>5.00</TotalCost>

            <CustomerOptions/>

        </Item>

    </Items>
</Order>
<Order id="3">
    <BillingInformation>
        <Name>Tom Brady</Name>
        <Address>One Patriot Place</Address>
        <City>Foxboro</City>
        <State>MA</State>
        <ZipCode>02035</ZipCode>
    </BillingInformation>
    <ShippingInformation>
        <Name>Tom Brady</Name>
        <Address>2121 George Halas Drive</Address>
        <City>Canton</City>
        <State>OH</State>
        <ZipCode>44708</ZipCode>
    </ShippingInformation>
    <Items>
        <Item>
            <PartNo>JETPANTS</PartNo>
            <Description>N.Y. Jets Sweatpants</Description>
            <UnitPrice>10.50</UnitPrice>
            <Quantity>3</Quantity>
            <TotalCost>31.50</TotalCost>
            <CustomerOptions>
                <Size>M</Size>
                <Color>Green</Color>
            </CustomerOptions>
        </Item>
        <Item>
            <PartNo>JETSWEATER</PartNo>
            <Description>N.Y. Jets Sweatshirt</Description>
            <UnitPrice>7.50</UnitPrice>
            <Quantity>1</Quantity>
            <TotalCost>7.50</TotalCost>

            <CustomerOptions>
                <Size>S</Size>
                <Color>White</Color>
            </CustomerOptions>
        </Item>
        <Item>
            <PartNo>JETSFLAG</PartNo>
            <Description>N.Y. Jets Flag for display</Description>
            <UnitPrice>5.00</UnitPrice>
            <Quantity>1</Quantity>
            <TotalCost>5.00</TotalCost>

            <CustomerOptions/>

        </Item>

    </Items>
</Order>
</OrderFeed>

我正在尝试访问 asp.net Web 服务应用程序中的客户选项。我不知道如何使用 XPath 表达式通过 Item 节点集来获取所有 Items，包括 Customer Options 节点集。我想要 PartNo、Description、UnitPrice、Quantity、TotalCost 和 customeroptions（如果有的话）。棘手的部分是我得到了一个例外，因为显然我最终会尝试将未为客户选项列出的数据存储到我制作的结构中。这就是我的网络服务功能。

[WebMethod]
    public lab3 GetItemListForOrder(int OrderID)
    {

        string strFileName = Server.MapPath("~\\XML_OrderInfo_Lab3.xml");
        XPathDocument xDoc = new XPathDocument(strFileName);
        //XPathNodeIterator NodeIter;
        XPathNavigator nav;
        XPathNodeIterator NodeIter;

        nav = xDoc.CreateNavigator();
        string searchstring = "//OrderFeed/Order[ " + OrderID + "]/Items//Item";

        NodeIter = nav.Select(searchstring);
        StringBuilder sb = new StringBuilder();

        while (NodeIter.MoveNext())
        {
            lab3 lab = new lab3();
            XPathNavigator Items = NodeIter.Current;
            lab.PartNO = Items.SelectSingleNode("PartNo").ToString();
            lab.Description = Items.SelectSingleNode("Description").ToString();
            lab.UnitPrice = Items.SelectSingleNode("UnitPrice").ToString();
            lab.TotalCost = Items.SelectSingleNode("TotalCost").ToString();

            lab.Size = Items.SelectSingleNode("Size").ToString();
            sb.Append(Items.SelectSingleNode("Color").ToString() + Environment.NewLine);
            return lab;
        }
    }

实验室之间。 TotalCost line 和 lab.Size，应该是某种检查，看看是否有可用的 customeroption。我只是想不通它以及之后如何使其正确显示。

Answer 1

您需要检查 CustomOptions

while (NodeIter.MoveNext())
        {
            lab3 lab = new lab3();
            XPathNavigator Items = NodeIter.Current;
            lab.PartNO = Items.SelectSingleNode("PartNo").ToString();
            lab.Description = Items.SelectSingleNode("Description").ToString();
            lab.UnitPrice = Items.SelectSingleNode("UnitPrice").ToString();
            lab.TotalCost = Items.SelectSingleNode("TotalCost").ToString();

          var CustomoptionNode = Items.Select("/CustomerOptions");
          string Color = string.Empty;
           if(CustomoptionNode != null)
       {
            lab.Size = CustomoptionNode .SelectSingleNode("Size").ToString();
            Color = CustomoptionNode .SelectSingleNode("Color").ToString();

      }


   sb.Append(Color  + Environment.NewLine);

            return lab;
   }