C#LINQ to XML:如何联接XML数据

本文关键字：XML 何联接 数据 to C#LINQ | 更新日期: 2023-09-27 18:06:53

给定如下两个XML文件：

<Customers>
  <Customer CustomerID="alc">Alice</Customer>
</Customer>

和

<Orders>
  <Order OrderID="001" CID="alc">apple</Order>
</Orders>

现在我需要连接这两个XML文件，并使用内部连接创建一个新文件：

<Result>
  <Join>
     <Customer CustomerID="alc">Alice</Customer>
     <Order OrderID="001" CID="alc">apple</Order>
  </Join>
</Result>

我有这个问题：

var result = new XElement("Result",
     from customer in XElement.Load("Customers.xml").Elements("Customer")
        join order in XElement.Load("Orders.xml").Elements("Order")
        on
            (string)customer.Attribute("CustomerID")
        equals
            (string)order.Attribute("CID")
        select new XElement("Join",
               new XElement("Customer", (string)customer.Element("Customer"),
               new XAttribute("CustomerID", (string)customer.Attribute("CustomerID"))),
               new XElement("Order", (string)order.Element("Order"),
               new XAttribute("OrderID", (string)order.Attribute("OrderID")),
               new XAttribute("CID", (string)order.Attribute("CID")))));
result.Save("result.xml");

有了这个，我就无法获得"爱丽丝"answers"苹果"的数据。结果是这样的：

<Result>
  <Join>
    <Customer CustomerID="alc" />
    <Order OrderID="001" CID="alc" />
  </Join>
</Result>

我想(string)customer.Element("Customer")和(string)order.Element("Order")可能有一些问题，我不知道如何修改这些问题。

C#LINQ to XML:如何联接XML数据

您只需将元素强制转换为string即可获得其文本值：

    select new XElement("Join",
           new XElement("Customer", (string)customer,
           new XAttribute("CustomerID", (string)customer.Attribute("CustomerID"))),
           new XElement("Order", (string)order,
           new XAttribute("OrderID", (string)order.Attribute("OrderID")),
           new XAttribute("CID", (string)order.Attribute("CID")))));

您可以在创建Join元素时简单地传递customer和order变量，而不是为相同的元素创建新的XElement：

select new XElement("Join", customer, order);

工作演示示例：

var customersxml = @"<Customers>
  <Customer CustomerID='alc'>Alice</Customer>
</Customers>";
var ordersxml = @"<Orders>
<Order OrderID='001' CID='alc'>apple</Order>
</Orders>";
var result = new XElement("Result",
                          from customer in XElement.Parse(customersxml).Elements("Customer")
                          join order in XElement.Parse(ordersxml).Elements("Order")
                          on (string)customer.Attribute("CustomerID") equals (string)order.Attribute("CID")
                          select new XElement("Join", customer, order));
Console.WriteLine(result.ToString());

输出：

<Result>
  <Join>
    <Customer CustomerID="alc">Alice</Customer>
    <Order OrderID="001" CID="alc">apple</Order>
  </Join>
</Result>
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