使用LINQ to XML将XML文件插入到现有XML文件中

Question

使用一些example code I found here on SO，我编写了一些代码来打开一个现有的XML数据库，打开另一个要插入到第一个XML中的XML文件，获取该文件中根节点的后代，并将它们附加到database.xml文件中所选节点的基础上，然后将结果文件保存到一个新的XML文件中。下面的代码在VS2010中编译和运行没有错误，但是没有将actionID.xml文件中的XML添加到database.xml文件中，我不知道我错过了什么。

下面是C#代码：

using System;
using System.Collections.Generic;
using System.Linq;
using System.Xml.Linq;

class pcbdbUpdate
{
static void Main( )
    {
        //open database & load into memory
        XDocument PCBDB = XDocument.Load("C:\\database.xml");
        //open Activity Log file & load into memory
        XDocument addAction = XDocument.Load("C:\\actionID.xml");
        //get descendant node(s) below PCBDBActivityLog root node
        var actionXML = addAction.Root.Descendants("PCBDBActivityLog");
        /*supposed to write out child nodes, but not very useful, just tells me
        it's a:  System.Xml.Linq.XContainer+<GetDescendants>d__a*/
        Console.WriteLine(actionXML.ToString());
        //enumerate database for SBE_PCB_Data nodes
        IEnumerable<XElement> SBE_PCB_Data = PCBDB.Element("PCBDatabase").Elements("SBE_PCB_Data");
        //look for specific node with PCBID of "00001" and select it
        XElement newAction = SBE_PCB_Data.Where(p => p.Attribute("PCBID").Value == "00001").FirstOrDefault();
        //write descendants from Activity Log to base of node
        newAction.Add(actionXML);
        //save the resultant file
        PCBDB.Save("C:\\newDatabase.xml");
    }
}

下面是database.xml：

<?xml version="1.0" encoding="utf-8"?>
<PCBDatabase>
  <SBE_PCB_Data PCBID="00001">
    <Creation ActionID="0002" User="DELLIOTTG:192.168.1.69" Date="2012-10-31T14:35:58" PCBID="00001">
      <PCBDrawing>00001a</PCBDrawing>
      <AssemblyDrawing>00001b</AssemblyDrawing>
      <Vendor>SBE</Vendor>
      <PONumber>00000</PONumber>
    </Creation>
    <Assignment ActionID="1295" User="RHO:192.168.1.6" Date="2012-12-13T08:59:31" PCBID="00001">
      <PCBDrawing>00002a</PCBDrawing>
      <AssemblyDrawing>00001c</AssemblyDrawing>
      <Vendor>SBE</Vendor>
      <PONumber>00001</PONumber>
    </Assignment>   
  </SBE_PCB_Data>
  <SBE_PCB_Data PCBID="00002">
    <Assignment ActionID="630c" User="DMUELLER:192.168.1.152" Date="2010-03-15T13:14:21" PCBID="00002">
      <SBEJobNumber>57380</SBEJobNumber>
    </Assignment>
  </SBE_PCB_Data>
</PCBDatabase>

下面是actionID.xml：

<?xml version="1.0"?>
<PCBDBActivityLog>
    <Assignment ActionID='8353' User='DMUELLER:192.168.1.134' Date='2011-01-27T15:38:25' PCBID='00001'>
        <SBEPN>41528E</SBEPN>
    </Assignment>
</PCBDBActivityLog>

生成的文件应如下所示：

<?xml version="1.0" encoding="utf-8"?>
<PCBDatabase>
  <SBE_PCB_Data PCBID="00001">
    <Creation ActionID="0002" User="DELLIOTTG:192.168.1.69" Date="2012-10-31T14:35:58" PCBID="00001">
      <PCBDrawing>00001a</PCBDrawing>
      <AssemblyDrawing>00001b</AssemblyDrawing>
      <Vendor>SBE</Vendor>
      <PONumber>00000</PONumber>
    </Creation>
    <Assignment ActionID="1295" User="RHO:192.168.1.6" Date="2012-12-13T08:59:31" PCBID="00001">
      <PCBDrawing>00002a</PCBDrawing>
      <AssemblyDrawing>00001c</AssemblyDrawing>
      <Vendor>SBE</Vendor>
      <PONumber>00001</PONumber>
    </Assignment>
    <Assignment ActionID='8353' User='DMUELLER:192.168.1.134' Date='2011-01-27T15:38:25' PCBID='00001'>
        <SBEPN>41528E</SBEPN>
    </Assignment>
  </SBE_PCB_Data>
  <SBE_PCB_Data PCBID="00002">
    <Assignment ActionID="630c" User="DMUELLER:192.168.1.152" Date="2010-03-15T13:14:21" PCBID="00002">
      <SBEJobNumber>57380</SBEJobNumber>
    </Assignment>
  </SBE_PCB_Data>
</PCBDatabase>

我遗漏了什么或做错了什么？

Answer 1

错误在这里：

var actionXML = addAction.Root.Descendants("PCBDBActivityLog")` 

您正在尝试在文档根目录下查找<PCBDBActivityLog>元素。但是这将不会返回任何内容，因为<PCBDBActivityLog>元素是一个actionID.xml文档的根。将此行替换为

var actionXML = addAction.Descendants("PCBDBActivityLog");

或

var actionXML = addAction.Root;