Using XmlTextReader

问题:

I am a beginner programmer starting off with C#, and web services.

In the Service.cs file of my web service, I create a ReadXMLFile() method where I am trying to read an existing XML file, take the data from it and place it to the corresponding properties (DataMembers) that I created in the IService.cs file.

My problem is that my code is basically not doing anything. I've tried looking for web sites and tutorials on this but there really isn't much out there, especially for a beginner like myself. Anyone have any idea how I should go about this, because what I've been trying so far is obviously wrong.

Below is my ReadXMLFile() method.

void ReadXMLFile()
{
    XmlTextReader reader = new XmlTextReader("ClassRoll.xml");
    reader.Read();
    while (reader.Read())
    {
        if (reader.Name == "id")
        {
            id = reader.ReadString();
        }
        else if (reader.Name == "firstname")
        {
            link = reader.ReadString();
        }
        else if (reader.Name == "lastname")
        {
            description = reader.ReadString();
        }
        else if (reader.Name == "count")
        {
            description = reader.ReadString();
        }
        else if (reader.Name == "testscore")
        {
            description = reader.ReadString();
        }
    }
}

this is an example of my xml file

<classroll>
  <student>
    <id>101010</id>
    <lastname>Smith</lastname>
    <firstname>Joe</firstname>
    <testscores count="5">
      <score>65</score>
      <score>77</score>
      <score>67</score>
      <score>64</score>
      <score>80</score>
    </testscores>
  </student>
</classroll>

回答1:

You're probably missing IsStartElement() condition in your while loop:

while (reader.Read())
{
    if (reader.IsStartElement())
    {
       if (reader.Name == "id")
       {
           id = reader.ReadString();
       }
...
}

Also, it would be easier to use XPath or LINQ to XML to read your XML, of course it depends on the file. Here are some examples: XPath and LINQ.

EDIT: after seeing XML file details

You should update your logic to keep track of current student and its testscores. Also, note that count is an attribute. It can get messy pretty soon, I suggest you take a look at the samples mentioned above.

回答2:

I think, that you get best result using XmlDocument

public void ReadXML()
{
    XmlDocument xmlDoc = new XmlDocument();
    xmlDoc.Load("<name file>.xml");
    xmlEntities = new List<XmlEntity>();

    foreach(XmlNode item in xmlDoc.ChildNodes)
    {
        GetChildren(item);
    }
}

private void GetChildren(XmlNode node)
{
    if (node.LocalName == "Строка")
    {
       //<you get the element here and work with it>
    }
    else
    {
       foreach (XmlNode item in node.ChildNodes)
       {
             GetChildren(item);
       }
    }
}

回答3:

The reason its not working because, example: when reader.Name == "firstname" is true but its not true with its elements value. What it exactly means is reader object reads next Nodetype, which is XmlNodeType.Element. So in this case looking at your XML file, using reader.Read(); function again reads next node, which is XmlNodeType.Text, and its value is then Joe. Im givin you example of working version.

void ReadXMLFile()
{
XmlTextReader reader = new XmlTextReader("ClassRoll.xml");
reader.Read();
while (reader.Read())
{
    if (reader.Name == "id")
    {
         reader.Read();
         if(reader.NodeType == XmlNodeType.Text)
         {
           id = reader.Value;
           reader.Read();
         }

    }
 }

}