如何更新元素中的xml文件元素值

Question

我有以下XML文件：

<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
<masterController>   <uuid>bcbd01ac-78ff-4656-997b-d4ccc72882d1</uuid>  
<channels>
    <channel>
      <nodeGroups>
        <nodeGroup>
          <analogNode>
            <typeCode>8</typeCode>
            <id>1</id>
            <sdos>
              <sdo>
                <description>Host ID</description>
                <compareLevel>Ignore</compareLevel>
                <datafield>
                  <description>Host ID</description>
                  <compareLevel>Ignore</compareLevel>
                  <offset>2</offset>
                  <size>1</size>
                  <readonly>true</readonly>
                  <isMappedToPdo>false</isMappedToPdo>
                  <ownerNodeSerial>12102904</ownerNodeSerial>
                  <ownerSdoIndex>3</ownerSdoIndex>
                  <data>
                    <value>2</value>
                    <unit></unit>
                    <min>1</min>
                    <max>15</max>
                  </data>
                  <intValue>2</intValue>
                </datafield>
                <index>3</index>
                <totalbytes>3</totalbytes>
              </sdo>
              <sdo>
                <description>Host ID</description>
                <compareLevel>Ignore</compareLevel>
                <datafield>
                  <description>Host ID</description>
                  <compareLevel>Ignore</compareLevel>
                  <offset>2</offset>
                  <size>1</size>
                  <readonly>true</readonly>
                  <isMappedToPdo>false</isMappedToPdo>
                  <ownerNodeSerial>12102905</ownerNodeSerial>
                  <ownerSdoIndex>4</ownerSdoIndex>
                  <data>
                    <value>16</value>
                    <unit></unit>
                    <min>1</min>
                    <max>15</max>
                  </data>
                  <intValue>2</intValue>
                </datafield>
                <index>3</index>
                <totalbytes>3</totalbytes>
              </sdo>
            </sdos>
            <sdos>
              <sdo>
                <description>Host ID</description>
                <compareLevel>Ignore</compareLevel>
                <datafield>
                  <description>Host ID</description>
                  <compareLevel>Ignore</compareLevel>
                  <offset>2</offset>
                  <size>1</size>
                  <readonly>true</readonly>
                  <isMappedToPdo>false</isMappedToPdo>
                  <ownerNodeSerial>12102907</ownerNodeSerial>
                  <ownerSdoIndex>3</ownerSdoIndex>
                  <data>
                    <value>ty</value>
                    <unit></unit>
                    <min>1</min>
                    <max>15</max>
                  </data>
                  <intValue>2</intValue>
                </datafield>
                <index>3</index>
                <totalbytes>3</totalbytes>
              </sdo>
              <sdo>
                <description>Host ID</description>
                <compareLevel>Ignore</compareLevel>
                <datafield>
                  <description>Host ID</description>
                  <compareLevel>Ignore</compareLevel>
                  <offset>2</offset>
                  <size>1</size>
                  <readonly>true</readonly>
                  <isMappedToPdo>false</isMappedToPdo>
                  <ownerNodeSerial>12102906</ownerNodeSerial>
                  <ownerSdoIndex>4</ownerSdoIndex>
                  <data>
                    <value>1.2</value>
                    <unit></unit>
                    <min>1</min>
                    <max>15</max>
                  </data>
                  <intValue>2</intValue>
                </datafield>
                <index>3</index>
                <totalbytes>3</totalbytes>
              </sdo>
            </sdos>
          </analogNode>
        </nodeGroup>
      </nodeGroups>
    </channel>   </channels> </masterController>

我創建了下面的代碼以更新上面的XML文件中的值。 但是，我的代碼不起作用。 誰能告訴我代碼有什么問題嗎？

public void updateXml()
        {
            XElement root = XElement.Load(Server.MapPath("Sample.xml"));
            var value = root.Descendants("datafield")
                .Where(x => (string)x.Element("ownerNodeSerial") == TextBox1.Text.ToString() &&
                            (string)x.Element("ownerSdoIndex") == TextBox2.Text.ToString())
                .Select(x => (string)x.Element("data").Element("value")).FirstOrDefault();


            root.SetElementValue(value, "505");



            root.Save("Sample.xml");

            Process.Start("Sample.xml");

        }
        void UpdateBcName(XElement query, object newValue)
        {
            query.Element("value").SetValue(newValue);
        }

        IEnumerable<XElement> LoadElementWhereReqNameEquals(XElement root, string reqName)
        {
            IEnumerable<XElement> queries = from el in root.Descendants("sdo")
                                            where (from add in el.Elements("datafield")
                                                   where
                                                       (string)add.Element("ownerNodeSerial") == TextBox1.Text &&
                                                       (string)add.Element("ownerSdoIndex") == TextBox2.Text
                                                   select add).Any()
                                            select el;

            return queries;
        }

任何幫助將不勝感激。

Answer 1

您實際使用的不是XElement.SetElementValue 。 您已經找到了第一個value元素的字符串值（例如“ 2”），然后將其用作要更新的元素的名稱 。 我懷疑您實際上想要的是：

var valueElement = root.Descendants("datafield")
    .Where(x => (string)x.Element("ownerNodeSerial") == TextBox1.Text &&
                (string)x.Element("ownerSdoIndex") == TextBox2.Text)
    .Select(x => x.Element("data").Element("value"))
    .FirstOrDefault();

valueElement.Value = 505;

請注意，我將其設置為int而不是字符串，因為我強烈懷疑它在邏輯上應為整數-讓LINQ to XML將其轉換為字符串表示形式。 同樣，我從TextBox1.Text和TextBox2.Text刪除了ToString調用。 我實際上建議將TextBox1.Text和TextBox2.Text解析為int值（或long或任何其他值），然后進行比較：

// TODO: Use int.TryParse instead, to handle invalid input cleanly
int ownerNodeSerial = int.Parse(TextBox1.Text);
int ownerSdoIndex = int.Parse(TextBox2.Text);

var valueElement = root.Descendants("datafield")
    .Where(x => (int)x.Element("ownerNodeSerial") == ownerSdoIndex &&
                (int)x.Element("ownerSdoIndex") == ownerNodeSerial)
    .Select(x => x.Element("data").Element("value"))
    .FirstOrDefault();
...