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); 
    } 
}