LINQ: How to Read XML PARAMETER Attributes

Hello everyone,

This is my first time to learn LINQ and I need to be able to query data quickly and store the information in an object. Not sure which thread to post this to, but I think C-Sharp Programming should be the correct thread.

Anyway, I have the following string :

Code:

---

theString = @"

<MgmtSystemInfo>
<LocalFixeDisk>
<Disks Drive="C:">
<Param Description="Local Fixed Disk" TimeStamp="4/26/2010 2:20:11 AM" />
<Param Compressed="No" TimeStamp="4/26/2010 2:20:11 AM" />
<Param FileSystem="NTFS" TimeStamp="4/26/2010 2:20:11 AM" />
<Param TotalSpace="149.05GB (160039239680bytes)" TimeStamp="4/26/2010 2:20:11 AM" />
<Param AvailableSpace="140.47GB (150827999232bytes)" TimeStamp="4/26/2010 2:20:11 AM" />
<Param PercentageAvaliable="94.24%" TimeStamp="4/26/2010 2:20:11 AM" />
<Param VolumeName="OS" TimeStamp="4/26/2010 2:20:11 AM" />
<Param VolumeSerialNumber="9C3F9B31" TimeStamp="4/26/2010 2:20:11 AM" />
</Disks>
</LocalFixeDisk>
<SystemInfo>
<Param OSName="Microsoft Windows XP Professional" TimeStamp="4/26/2010 2:20:11 AM" />
<Param Version="5.1.2600 Service Pck 2 Build 2600" TimeStamps="4/26/2010 2:20:11 AM" />
<Param OSManufacturer="Microsoft Corporation" TimeStamps="4/26/2010 2:20:11 AM" />
<Param SN=" 1234567" TimeStamps="4/26/2010 2:20:11 AM" /
<Param WindowsDirectory="C:\WINDOWS" TimeStamps="4/26/2010 2:20:11 AM" />
</SystemInfo>
<MgmtSystemInfo>"

---

I need to be able to read each Param attribute from say, the <Disks> </Disks> section of this XML string.

For instance, i want to be able to read the Description attribute in this section of the above XML :

Code:

---

<Param Description="Local Fixed Disk" TimeStamp="4/26/2010 2:20:11 AM" />

---

and then programatically read the rest of the attributes in each PARAM section, say, the Compressed and FileSystem attributes, etc.

<

Code:

---

Param Compressed="No" TimeStamp="4/26/2010 2:20:11 AM" />
<Param FileSystem="NTFS" TimeStamp="4/26/2010 2:20:11 AM" />

---

and so on...


How do I do this ?

I tried this snippet as an example but it does not work ( I get an exception when I added the commented out lines below )

Code:

---

class Param
{
public string Description { get; set; }
public string Compressed { get; set; }
public string FileSystem { get; set; }
public string TotalSpace { get; set; }
public string AvailableSpace { get; set; }
public string PercentageAvailable { get; set; }
public string Volumename { get; set; }
public string VolumeSerialNum { get; set; }
};

public class DiskDrives
{
public string Drive { get; set; }
}

XDocument xdoc = Xdocument.Parse(theString);


List<DiskDrives> LocalDisks =
(from drives in xdoc.Descendants("Disks")
select new DiskDrives
{
Drive = drives.Attribute("Drive").Value,
}).ToList<DiskDrives>();

int cnt = 0;

foreach (var drives in LocalDisks)
{
Console.WriteLine("Drive: " + drives.Drive.ToString());
var Parameters = from theparam in xdoc.Descendants("Disks")
where (theparam.Attribute("Drive").Value == drives.Drive)
select new Param
{
Description = theparam.Element("Param").Attribute("Description").Value,

// Note, I had to comment the next two lines out as they were causing exceptions.
// My intent is to capture the rest of the attributes in the above XML string

// Compressed = theparam.Element("Param").Attribute("Compressed").Value,
//FileSystem = theparam.Element("Param").Attribute("FileSystem").Value,
};

foreach (var item in Parameters)
{
Console.WriteLine("Item: " + item.Description); // I get the correct value here "Local Fixed Disk"
Console.WriteLine("Item: " + item.Compressed); // The value should be "No"
Console.WriteLine("Item: " + item.FileSystem); // The value should be "NTFS"
}
}

---

In the above code, the commented out lines cause exceptions.

I am able to get the Description attribute of the first <PARAM />
section, but do not know how I can get the other attributes programatically ( e.g., the Compressed and FileSystem attributes ).

Your help/advise regarding this matter will be highly appreciated.

DISCLAIMER: the linq use in this example is gratuitous for demonstration purposes.

This example will work for any number of <Disk> elements, containing any number of <Param> elements. I leave it to you to implement the same functionality for the <SystemInfo> element(s).

Code:

---



using System;
using System.Text;
using System.Linq;
using System.Xml.Linq;
using System.Reflection;
using System.Collections.Generic;

namespace XElementParsing
{
    class Program
    {
        static void Main(string[] args)
        {
            XDocument xDocument = XDocument.Parse(
            "<MgmtSystemInfo>" +
                "<LocalFixeDisk>" +
                    "<Disks Drive=\"C:\">" +
                        "<Param Description=\"Local Fixed Disk\" TimeStamp=\"4/26/2010 2:20:11 AM\" />" +
                        "<Param Compressed=\"No\" TimeStamp=\"4/26/2010 2:20:11 AM\" />" +
                        "<Param FileSystem=\"NTFS\" TimeStamp=\"4/26/2010 2:20:11 AM\" />" +
                        "<Param TotalSpace=\"149.05GB (160039239680bytes)\" TimeStamp=\"4/26/2010 2:20:11 AM\" />" +
                        "<Param AvailableSpace=\"140.47GB (150827999232bytes)\" TimeStamp=\"4/26/2010 2:20:11 AM\" />" +
                        "<Param PercentageAvailable=\"94.24%\" TimeStamp=\"4/26/2010 2:20:11 AM\" />" +
                        "<Param VolumeName=\"OS\" TimeStamp=\"4/26/2010 2:20:11 AM\" />" +
                        "<Param VolumeSerialNumber=\"9C3F9B31\" TimeStamp=\"4/26/2010 2:20:11 AM\" />" +
                        "<Param TestParam=\"Testing...\" />" +
                    "</Disks>" +
                "</LocalFixeDisk>" +
                "<SystemInfo>" +
                    "<Param OSName=\"Microsoft Windows XP Professional\" TimeStamp=\"4/26/2010 2:20:11 AM\" />" +
                    "<Param Version=\"5.1.2600 Service Pck 2 Build 2600\" TimeStamps=\"4/26/2010 2:20:11 AM\" />" +
                    "<Param OSManufacturer=\"Microsoft Corporation\" TimeStamps=\"4/26/2010 2:20:11 AM\" />" +
                    "<Param SN=\" 1234567\" TimeStamps=\"4/26/2010 2:20:11 AM\" />" +
                    "<Param WindowsDirectory=\"C:\\WINDOWS\" TimeStamps=\"4/26/2010 2:20:11 AM\" />" +
                "</SystemInfo>" +
            "</MgmtSystemInfo>");

            List<Disk> disks = GetDisks(xDocument).ToList();
            foreach( Disk disk in disks ) { Console.WriteLine(disk.ToString()); }
        }

       


        public static IEnumerable<Disk> GetDisks(XDocument xDocument)
        {
            var disks =
                xDocument.Descendants("Disks")
              .Select(d => new Disk()
              {
                  Drive = d.Attribute("Drive").Value,
                  Parameters = GetDiskParameters(d)

              });

            return disks;
        }

     


        public static DiskParameters GetDiskParameters(XElement xElement)
        {
            DiskParameters parameters = new DiskParameters();

            string[] propertyNames = parameters.GetType().GetProperties()
                                        .Select(p => p.Name)
                                        .ToArray();

            foreach( XElement xParam in xElement.Elements("Param") )
            {
                if( propertyNames.Contains(xParam.FirstAttribute.Name.ToString()) )
                {
                    PropertyInfo property = parameters.GetType().GetProperty(xParam
                                          .FirstAttribute.Name
                                          .ToString());

                    property.SetValue(parameters, xParam.FirstAttribute.Value, null);
                }
            }

            return parameters;
        }
    }

   


    public class Disk
    {
        public string Drive { get; set; }
        public DiskParameters Parameters { get; set; }

        public override string ToString()
        {
            StringBuilder sb = new StringBuilder();
            sb.Append(string.Format("Drive = {0}\n", Drive));

            foreach( PropertyInfo property in Parameters.GetType().GetProperties() )
            {
                sb.Append(string.Format(
                    "{0} = {1}\n",
                    property.Name,
                    (string)property.GetValue(Parameters, null)
                ));
            }

            return sb.ToString();
        }
    }

 


    public class DiskParameters
    {
        public string Description { get; set; }
        public string Compressed { get; set; }
        public string FileSystem { get; set; }
        public string TotalSpace { get; set; }
        public string AvailableSpace { get; set; }
        public string PercentageAvailable { get; set; }
        public string VolumeName { get; set; }
        public string VolumeSerialNumber { get; set; }
    }
}

---

Alternatively, we could have populated the Disk Parameters like

Code:

---



var disks =
                xDocument.Descendants("Disks")
              .Select(d => new Disk()
              {
                  Drive = d.Attribute("Drive").Value,
                  Parameters = new DiskParameters()
                  {
                      Description = d.Elements("Param").ElementAt(0).Attribute("Description").Value,
                      Compressed = d.Elements("Param").ElementAt(0).Attribute("Description").Value,
                      //...
                  }
              });

---

but then if the number of <Param> elements in the XML changes unexpectedly, an exception will be thrown, so I use reflection (bcuz I'm a lazy typer) plus a test to see if the <Param>'s attribute is a known property.

This means the only place I need to add code if the XML changes, is in the Disk Parameter's implementation. I'd simply add another property to accomodate.

(BTW: I added an extra <Param> tag (has attribute: "TestParam="Testing...") to show that this example won't fail just because the number of <Param>s changes)

StainedBlue,

Thanks for your helpful response. Much appreciated.

In fact, your solution is safer and a better catch all solution than the one I just thought of ( see below ):

I also thought about the problem and thought about this solution :

I would like to share with all in this forum for your future reference ( critiques are welcome of course ).

Again the XML string is :

Code:

---

<MgmtSystemInfo>
  <LocalFixeDisk>
    <Disks Drive="C:">
      <Param Description="Local Fixed Disk" TimeStamp="4/26/2010 2:20:11 AM" />
      <Param Compressed="No" TimeStamp="4/26/2010 2:20:11 AM" />
      <Param FileSystem="NTFS" TimeStamp="4/26/2010 2:20:11 AM" />
      <Param TotalSpace="149.05GB (160039239680bytes)" TimeStamp="4/26/2010 2:20:11 AM" />
      <Param AvailableSpace="140.47GB (150827999232bytes)" TimeStamp="4/26/2010 2:20:11 AM" />
      <Param PercentageAvaliable="94.24%" TimeStamp="4/26/2010 2:20:11 AM" />
      <Param VolumeName="OS" TimeStamp="4/26/2010 2:20:11 AM" />
      <Param VolumeSerialNumber="9C3F9B31" TimeStamp="4/26/2010 2:20:11 AM" />
    </Disks>
  </LocalFixeDisk>
  <SystemInfo>
    <Param OSName="Microsoft Windows XP Professional" TimeStamp="4/26/2010 2:20:11 AM" />
    <Param Version="5.1.2600 Service Pck 2 Build 2600" TimeStamps="4/26/2010 2:20:11 AM" />
    <Param OSManufacturer="Microsoft Corporation" TimeStamps="4/26/2010 2:20:11 AM" />
    <Param SN=" 1234567" TimeStamps="4/26/2010 2:20:11 AM" />
    <Param WindowsDirectory="C:\WINDOWS" TimeStamps="4/26/2010 2:20:11 AM" />
  </SystemInfo>
  </MgmtSystemInfo>

---

I looked at the XML string again and I did notice that the Param sections consist of Key/Value pairs that need to be captured in some sort of Key/Val data structure ( for instance, Description is a key and "Local Fixed Disk" is the value ).

Hence, I modified the code to look like this ( modified the class to capture the XML data ):

---------------------------------------------------------------------------------------------

Code:

---

public class DiskDrives
{
  public string DriveName { get; set; }
  public SortedList<string, string> DiskParams; // Intended to be Key/Val pair
} // End class DiskDrivesI

---

I then modified the LINQ code as follows :

---------------------------------------------------------------------------------------------

Code:

---

XDocument xdoc = XDocument.Parse(Properties.Resources.TheString);

// Get Data for the LocalFixeDisk section --- Drive and corresponding Parameters

ListWksDrives =
(from drives in xdoc.Descendants("Disks")
select new DiskDrives{
  DriveName = drives.Attribute("Drive").Value,
}).ToList<DiskDrives>();

// From hereon, we get the Param key/val pairs

int cnt = ListWksDrives.Count();

foreach (var drives in ListWksDrives)
{
  // Console.WriteLine("Drive: " + drives.DriveName.ToString());
  drives.DiskParams = new SortedList<string, string>(cnt);
   
  foreach (XElement elem in xdoc.Descendants("Disks"))
  {
      var MyParams = elem.Elements("Param");
      foreach (XElement elem1 in MyParams)
      {
          Console.WriteLine(" Key/Val : " + elem1.FirstAttribute.Name + "/" +
                                            elem1.FirstAttribute.Value);
          if (elem.Attribute("Drive").Value.ToString() == drives.DriveName){
        drives.DiskParams.Add(elem1.FirstAttribute.Name.ToString(),
                                                    elem1.FirstAttribute.Value.ToString());
        }
  }
}
}// End foreach (var drives in ListWksDrives)

Console.WriteLine("************ DISK INFO *****************");
Console.WriteLine();

for (int i=0; i < ListWksDrives.Count; i++)
{
    Console.WriteLine("Disk Drive: " + ListWksDrives[i].DriveName);
   
    foreach (KeyValuePair<string, string> keyValPair in ListWksDrives[i].DiskParams)
    {
          Console.WriteLine("Key:" + keyValPair.Key + " Value: " + keyValPair.Value);
    }
}

---