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「Linqtoxml」に頭を悩ませようとしているので、すぐにジャンプしましょう。私はこのxmlを持っています：

<?xml version="1.0"?>
<PurchaseOrders>
  <PurchaseOrder PurchaseOrderNumber="99503" OrderDate="1999-10-20">
    <Address Type="Shipping">
      <Name>Ellen Adams</Name>
      <Street>123 Maple Street</Street>
      <City>Mill Valley</City>
      <State>CA</State>
      <Zip>10999</Zip>
      <Country>USA</Country>
    </Address>
    <Address Type="Billing">
      <Name>Tai Yee</Name>
      <Street>8 Oak Avenue</Street>
      <City>Old Town</City>
      <State>PA</State>
      <Zip>95819</Zip>
      <Country>USA</Country>
    </Address>
    <DeliveryNotes>Please leave packages in shed by driveway.</DeliveryNotes>
    <Items>
      <Item PartNumber="872-AA">
        <ProductName>Lawnmower</ProductName>
        <Quantity>1</Quantity>
        <USPrice>148.95</USPrice>
        <Comment>Confirm this is electric</Comment>
      </Item>
      <Item PartNumber="926-AA">
        <ProductName>Baby Monitor</ProductName>
        <Quantity>2</Quantity>
        <USPrice>39.98</USPrice>
        <ShipDate>1999-05-21</ShipDate>
      </Item>
    </Items>
  </PurchaseOrder>
</PurchaseOrders>

そして、私はいくつかの単純なオブジェクトを作成しました：

public class PurchaseOrder
{
    public string PurchaseOrderNumber { get; set; }
    public string OrderDate { get; set; }
    public Address BillingAddress { get; set; }
    public Address ShippingAddress { get; set; }
    public string DeliveryNotes { get; set; }
    public List<Item> Items { get; set; }
}

public class Address
{
    public string Type { get; set; }
    public string Name  { get; set; }
    public string Street { get; set; }
    public string City { get; set; }
    public string State { get; set; }
    public string Zip { get; set; }
    public string Country { get; set; }
}

public class Item
{
    public string PartNumber { get; set; }
    public string ProductName { get; set; }
    public string Quantity { get; set; }
    public string USPrice { get; set; }
    public string Comment { get; set; }
}

それから私は先に進んで私のlinqを作ります：

    var orders = (from order in XDocument.Load(Server.MapPath("/App_Data/Order.xml")).Descendants("PurchaseOrder")
select new PurchaseOrder
{
    PurchaseOrderNumber = order.Attribute("PurchaseOrderNumber").Value,
    OrderDate = order.Attribute("OrderDate").Value,
    BillingAddress = new Address
    {
        City = order.Descendants("Address").Where(a => a.Attribute("Type").Value == "Billing").Single().Element("City").Value,
        Country = order.Descendants("Address").Where(a => a.Attribute("Type").Value == "Billing").Single().Element("Country").Value,
        Name = order.Descendants("Address").Where(a => a.Attribute("Type").Value == "Billing").Single().Element("Name").Value,
        State = order.Descendants("Address").Where(a => a.Attribute("Type").Value == "Billing").Single().Element("State").Value,
        Street = order.Descendants("Address").Where(a => a.Attribute("Type").Value == "Billing").Single().Element("Street").Value,
        Type = "Billing",
        Zip = order.Descendants("Address").Where(a => a.Attribute("Type").Value == "Billing").Single().Element("Zip").Value
    },
    ShippingAddress = new Address
    {
        City = order.Descendants("Address").Where(a => a.Attribute("Type").Value == "Shipping").Single().Element("City").Value,
        Country = order.Descendants("Address").Where(a => a.Attribute("Type").Value == "Shipping").Single().Element("Country").Value,
        Name = order.Descendants("Address").Where(a => a.Attribute("Type").Value == "Shipping").Single().Element("Name").Value,
        State = order.Descendants("Address").Where(a => a.Attribute("Type").Value == "Shipping").Single().Element("State").Value,
        Street = order.Descendants("Address").Where(a => a.Attribute("Type").Value == "Shipping").Single().Element("Street").Value,
        Type = "Shipping",
        Zip = order.Descendants("Address").Where(a => a.Attribute("Type").Value == "Shipping").Single().Element("Zip").Value
    },
    DeliveryNotes = order.Element("DeliveryNotes").Value,
    Items = null
});

まず、「order.Element（ "DeliveryNotes"）。Value」が出力xmlに存在せず、「オブジェクト参照がオブジェクトのインスタンスに設定されていない」とスローされるのはなぜですか？

次に、アドレスの「タイプ」（属性）を取得するにはどうすればよいですか？

第三に、アイテムのリストを「Items = null」にして、完全に機能するオブジェクトを操作するにはどうすればよいですか？

そして最後に、linqの残りの部分がsomチューニングを必要とする場合は、先に進んで正しい方向に私を導きます; o）

4

1 に答える 1

1

UPDATEvalueコードを書き直したので、現在プロパティ を使用していません。また、Itemsリストにデータを入力する必要があります。

このトピックは非常に便利です。

LINQtoXMLオプション要素クエリ

Linq To XmlのNull参照例外をどのように保護しますか？

var doc = XDocument.Load(@"C:\Temp\stackoverflow.xml");

var ordersTemp = 
    (from order in doc.Descendants("PurchaseOrder") select 
            new {
                order,
                BillingAddress = order.Descendants("Address").Where(a => a.Attribute("Type").Value == "Billing").Single(),
                ShippingAddress = order.Descendants("Address").Where(a => a.Attribute("Type").Value == "Shipping").Single(),
                Items = order.Descendants("Items").Descendants("Item")
            });

var orders = (from order in ordersTemp select  
    new PurchaseOrder
    {
        PurchaseOrderNumber = (string)order.order.Attribute("PurchaseOrderNumber"),
        OrderDate = (string)order.order.Attribute("OrderDate"),
        BillingAddress = new Address
        {
            City = (string)order.BillingAddress.Element("City"),
            Country = (string)order.BillingAddress.Element("Country"),
            Name = (string)order.BillingAddress.Element("Name"),
            State = (string)order.BillingAddress.Element("State"),
            Street = (string)order.BillingAddress.Element("Street"),
            Type = "Billing",
            Zip = (string)order.BillingAddress.Element("Zip")
        },
        ShippingAddress = new Address
        {
            City = (string)order.ShippingAddress.Element("City"),
            Country = (string)order.ShippingAddress.Element("Country"),
            Name = (string)order.ShippingAddress.Element("Name"),
            State = (string)order.ShippingAddress.Element("State"),
            Street = (string)order.ShippingAddress.Element("Street"),
            Type = "Shipping",
            Zip = (string)order.ShippingAddress.Element("Zip")
        },
        DeliveryNotes = (string)order.order.Element("DeliveryNotes"),
        Items = (from item in order.Items select new Item
        {
            PartNumber = (string)item.Attribute("PartNumber"),
            ProductName = (string)item.Element("ProductName"),
            Quantity = (string)item.Element("Quantity"),
            USPrice = (string)item.Element("USPrice"),
            Comment = (string)item.Element("Comment")
        }).ToList()
    });
于 2012-11-01T07:34:34.960 に答える