Read nodes of a xml file in C#

Question

How can I read the following xml file into a List:

Partial XML file (data.log)

<ApplicationLogEventObject>
    <EventType>Message</EventType>
    <DateStamp>10/13/2016 11:15:00 AM</DateStamp>
    <ShortDescription>N/A</ShortDescription>
    <LongDescription>Sending 'required orders' email.</LongDescription>
</ApplicationLogEventObject>
<ApplicationLogEventObject>
    <EventType>Message</EventType>
    <DateStamp>10/13/2016 11:15:10 AM</DateStamp>
    <ShortDescription>N/A</ShortDescription>
    <LongDescription>Branches Not Placed Orders - 1018</LongDescription>
</ApplicationLogEventObject>
<ApplicationLogEventObject>
    <EventType>Message</EventType>
    <DateStamp>10/13/2016 11:15:10 AM</DateStamp>
    <ShortDescription>N/A</ShortDescription>
    <LongDescription>Branches Not Placed Orders - 1019</LongDescription>
</ApplicationLogEventObject>
...

And here is the data access layer (DAL):

public List<FLM.DataTypes.ApplicationLogEventObject> Get()
    {
        try
        {
            XmlTextReader xmlTextReader = new XmlTextReader(@"C:\data.log");
        List<FLM.DataTypes.ApplicationLogEventObject> recordSet = new List<ApplicationLogEventObject>();

        xmlTextReader.Read();

        while (xmlTextReader.Read())
        {
            xmlTextReader.MoveToElement();
            FLM.DataTypes.ApplicationLogEventObject record = new ApplicationLogEventObject();

            record.EventType = xmlTextReader.GetAttribute("EventType").ToString();
            record.DateStamp = Convert.ToDateTime(xmlTextReader.GetAttribute("DateStamp"));
            record.ShortDescription = xmlTextReader.GetAttribute("ShortDescription").ToString()                    
            record.LongDescription = xmlTextReader.GetAttribute("LongDescription").ToString();

            recordSet.Add(record);
        }
        return recordSet;
    }
    catch (Exception ex)
    {
        throw ex;
    }
}

And the Data Types which will hold the child elements from the XML file:

public class ApplicationLogEventObject
{
    public string EventType { get; set; }
    public DateTime DateStamp { get; set; }
    public string ShortDescription { get; set; }
    public string LongDescription { get; set; }
}

After I've read the child nodes into a List I would then like to return it and display it in a DataGridView.

Any help regarding this question will be much appreciated.

Answer 1

Your log file is not an XML document. Since an XML document must have one and only one root element, it's a series of XML documents concatenated together. Such a series of documents can be read by XmlReader by setting XmlReaderSettings.ConformanceLevel == ConformanceLevel.Fragment. Having done so, you can read through the file and deserialize each root element individually using XmlSerializer as follows:

static List<ApplicationLogEventObject> ReadEvents(string fileName)
{
    return ReadObjects<ApplicationLogEventObject>(fileName);
}

static List<T> ReadObjects<T>(string fileName)
{
    var list = new List<T>();

    var serializer = new XmlSerializer(typeof(T));
    var settings = new XmlReaderSettings { ConformanceLevel = ConformanceLevel.Fragment };
    using (var textReader = new StreamReader(fileName))
    using (var xmlTextReader = XmlReader.Create(textReader, settings))
    {
        while (xmlTextReader.Read())
        {   // Skip whitespace
            if (xmlTextReader.NodeType == XmlNodeType.Element) 
            {
                using (var subReader = xmlTextReader.ReadSubtree())
                {
                    var logEvent = (T)serializer.Deserialize(subReader);
                    list.Add(logEvent);
                }
            }
        }
    }

    return list;            
}

Using the following version of ApplicationLogEventObject:

public class ApplicationLogEventObject
{
    public string EventType { get; set; }

    [XmlElement("DateStamp")]
    public string DateStampString { 
        get
        {
            // Replace with culturally invariant desired formatting.
            return DateStamp.ToString(CultureInfo.InvariantCulture);
        }
        set
        {
            DateStamp = Convert.ToDateTime(value, CultureInfo.InvariantCulture);
        }
    }

    [XmlIgnore]
    public DateTime DateStamp { get; set; }

    public string ShortDescription { get; set; }
    public string LongDescription { get; set; }
}

Sample .Net fiddle.

Notes:

• The <DateStamp> element values 10/13/2016 11:15:00 AM are not in the correct format for dates and times in XML, which is ISO 8601. Thus I introduced a surrogate string DateStampString property to manually handle the conversion from and to your desired format, and then marked the original DateTime property with XmlIgnore.

• Using ReadSubtree() prevents the possibility of reading past the end of each root element when the XML is not indented.

• According to the documentation for XmlTextReader:

  Starting with the .NET Framework 2.0, we recommend that you use the System.Xml.XmlReader class instead.

  Thus I recommend replacing use of that type with XmlReader.

• The child nodes of your <ApplicationLogEventObject> are elements not attributes, so XmlReader.GetAttribute() was not an appropriate method to use to read them.

• Given that your log files are not formatting their times in ISO 8601, you should at least make sure they are formatted in a culturally invariant format so that log files can be exchanged between computers with different regional settings. Doing your conversions using CultureInfo.InvariantCulture ensures this.