使用C＃解析XML，获取属性值

Question

I have the following (simplified) notepad file, which from what I understand is XML text:

<?xml version="1.0" encoding="utf-8"?>
  <appSettings>
        <add key="Active_01" value="1">
        </add>
  </appSettings>

I am trying to parse it using C#.

So far I have the following:

public class RFIDScanner
{
    public void GetScannerConfigFile()
    {
        string File = ConfigurationManager.AppSettings["RFIDScannerConfiguration"];

        XmlDocument doc = new XmlDocument();
        doc.Load(File);

        XmlNode node = doc.DocumentElement.SelectSingleNode("/appSettings");

        String nodename = node.Name;

    }
}

So far I know this is all correct, as:

nodename = appSettings

Which is as it should be.

My problem is, how do I retrieve the value "1" from the field "Active_01".

I now know that the node "add" is a child of the node "appSettings", and a trying to work out how to get the value stored in it.

Answer 1

There are many ways, one is to use the XPath using the function you use above:

var value = doc.DocumentElement.SelectSingleNode("/appSettings/add/@value");

Another option is to use xml serialization :

You'd define classes as follows:

public class add
{
    [XmlAttribute]
    public string key;
    [XmlAttribute]
    public int value;
}

public class appSettings
{
    public add add;
}

And then deserialize as follows:

var ser = new XmlSerializer(typeof(appSettings));
var xmlReader = new XmlTextReader(new StringReader(s));
appSettings settings = (appSettings) ser.Deserialize(xmlReader);
xmlReader.Close();

You can then get the values from settings

Answer 2

Not sure if you wish to parse the '1' from the key Active_01 , or get the 1 from the value. In Any case, you can use the following code:

    public void GetScannerConfigFile()
    {
        string File = ConfigurationManager.AppSettings["RFIDScannerConfiguration"];

        XmlDocument doc = new XmlDocument();
        doc.Load(File);

        var yourFile = doc.DocumentElement;
        if (yourFile == null) return;

        // Here you'll get the attribute key: key = Active_01 - which can be simply parsed for getting only the "1"
        string key = yourFile.ChildNodes[0].Attributes["key"].Value;

        // Here you'll get the number "1" from the value attribute.
        string value = yourFile.ChildNodes[0].Attributes["value"].Value;
    }

Answer 3

I have used this way in my code to add values to xml may be it will help

var surveyTypeList = new XElement("SurveyTypes");
            foreach (var item in modelData.SurveyTypeList)
            {
                if (item.IsSelected)
                {
                    var surveyType = new XElement("SurveyType");
                    var id = new XElement("Id");
                    id.Add(item.Value);
                  //  **var i= id.Value**
                    surveyType.Add(id);
                    surveyTypeList.Add(surveyType);
                }
            }

you can get value by var i= id.Value in your code;