Reading Specific elements using XMLReader and adding values to a generic List

Question

I am reading a huge XML file (250 MB) using XMLReader and add only specific elements to a generic List . I am unable to add values to the list correctly.I am getting null values in the List.I'll appreciate your help Below is the class I am using :

public class SomeInfo
    {
       public string Item1 { get; set; }

       public string Item2 { get; set; }

    }

My code to read XML is as below :

using (XmlReader reader = XmlReader.Create(file)
                )
            {
                List<SomeInfo> test = new List<SomeInfo>();

                while (reader.Read())
                {
                    var testObject = new SomeInfo();
                    if (reader.NodeType == XmlNodeType.Element)
                    {

                        string name = reader.Name;
                        switch (name)
                        {
                            case "Item1":
                                reader.Read();
                                testObject.item1= reader.Value;
                                break;
                            case "Item2":
                                reader.Read();
                                testObject.item2= reader.Value;
                                break;
                        }
            test.Add(testObject);
                    }

                    }

Sample XML : This is huge xml file and I only need to read some elements and add to the list .In my code above, I am only reading Item1 and Item2 and do not care about Xitem,Bitem and Citem tags

<mainItem>
<Item>
      <Xitem>125</Xitem>
      <Item1>ab41gh80020gh140f6</Item1>
      <BItem>42ae3de3</BItem>
      <Item2>7549tt80384</Item2>
      <Citem>c7dggf66e4</Citem>
</Item>
<Item>
      <Xitem>865</Xitem>
      <Item1>ab41gh80020gh140f6</Item1>
      <BItem>42aejj3de3</BItem>
      <Item2>7549kljj80384</Item2>
      <Citem>c7df6kk6e4</Citem>
</Item>
<Item>
      <Xitem>895</Xitem>
      <Item1>ab41gjgjgh80020gh140f6</Item1>
      <BItem>42aehkh3de3</BItem>
      <Item2>754980384</Item2>
      <Citem>c7dfjj66e4</Citem>
</Item>
    </mainItem>

reader.Read() reads the next node from the stream. In your algorithm, for each node like mainItem,XItem, Item1 you are creating an instance of SomeInfo class. So your list will have 19 elements instead of 3. I would suggest you to try deserialize xml — Mechanical Object

Damith Damith · Accepted Answer · 2013-07-25T05:02:23

change as below

private List<SomeInfo> ProcessItems(XmlTextReader reader)
{
    List<SomeInfo> test = new List<SomeInfo>();
    while (reader.Read())
    {
        if (reader.Name.Equals("Item"))
        {
            var testObject = new SomeInfo();
            while (reader.Read())
            {
                if (reader.NodeType == XmlNodeType.EndElement && reader.Name.Equals("Item"))
                {
                    break;
                }
                if (reader.NodeType == XmlNodeType.Element)
                {
                    switch (reader.Name)
                    {
                        case "Item1":
                            testObject.Item1 = reader.ReadString();
                            break;
                        case "Item2":
                            testObject.Item2 = reader.ReadString();
                            break;
                    }
                }
            }
            test.Add(testObject);

        }
    }
    return test;

}

Usage :

XmlTextReader reader = new XmlTextReader(filepath));
List<SomeInfo> result = ProcessItems(reader);

Reading Specific elements using XMLReader and adding values to a generic List

2 Answers