XML - xDoc.XPathSelectElements

Question

XML - xDoc.XPathSelectElements

Markus Freitag 3,791

Hello!

I am reading in the XML file and cannot cast to my list.
Why not.
With the var type it works. Then I have to copy everything again? What can be the cause? What is the solution?

<REASONS_STOP_BEFORE_TARGET>
    <REASON value="No Material"/>
    <REASON value="Changed operator"/>
    <REASON value="End of shift"/>
</REASONS_STOP_BEFORE_TARGET>

public class REASONS_STOP_BEFORE_TARGET : List<REASON>
{
 public REASONS_STOP_BEFORE_TARGET()
 {

 }

 //....
public class REASON
 {
 public string Value { set; get; }


 var result = (from e in xDoc.XPathSelectElements("//REASON")
   select new REASON
   {
   Value = e.Attribute("value").Value
   }).ToList();

// ** Works with var type  


// *** That works not, why?
REASONS_STOP_BEFORE_TARGET result = (from e in xDoc.XPathSelectElements("//REASON")
   select new REASON
   {
   Value = e.Attribute("value").Value
   }).ToList();

// ** Not work, why? Casting problem?

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Answer 1

Viorel 127K

If you decided to derive REASONS_STOP_BEFORE_TARGET from List and to use LINQ, then check this code:

public class REASONS_STOP_BEFORE_TARGET : List<REASON>
{
   public REASONS_STOP_BEFORE_TARGET( IEnumerable<REASON> collection ) : base( collection )
   {
   }
}

. . .

REASONS_STOP_BEFORE_TARGET result =
   new REASONS_STOP_BEFORE_TARGET( from e in xDoc.XPathSelectElements( "/*/REASON" )
                                   select new REASON
                                   {
                                      Value = e.Attribute( "value" ).Value
                                   } );

Markus Freitag 3,791

Hello,
works. Yes.

   ReasonsForStop = new REASONS_STOP_BEFORE_TARGET((from e in xDoc.XPathSelectElements("//REASON")
                          select new REASON
                          {
                              Value = e.Attribute("value").Value
                          }).ToList());

ReasonsForStop
The list is already there, now I have to add elements from a file. Can I merge them?

// Presettings are in the list.

ReasonsForStop = new REASONS_STOP_BEFORE_TARGET();

 REASON varReason;
            varReason = new REASON() { Value = "PreSetting1" } ;
            ReasonsForStop.Add(varReason);

Viorel 127K

If the list object already exists and you want to append data, then you can write something like this:

ReasonsForStop.AddRange( from e in xDoc.XPathSelectElements( "//REASON" )
                         select new REASON
                         {
                            Value = e.Attribute( "value" ).Value
                         } );

Markus Freitag 3,791 Reputation points

2021-07-16T19:26:02.373+00:00

Question answered, thank you very much.

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XML - xDoc.XPathSelectElements

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