LINQ to XML的条款

Question

The following code should return all barcodes that are in the filter. however it seems to excecute the filter only on the first newrecord.

the xml contains 5 newrecords with a barcode subelement ranging 1-5. if the filter contains 1,3 and 4 it returns 1 and if the filter contains 2,3 and 4 it returns a no records.

Also the current setup (rpa.XMLData.Elements("NEWFILE").Elements("NEWRECORD") ) returns 5 rows. i have tried seeing what happens if i change this to comeback in a single row (rpa.XMLData.Elements("NEWFILE")) but this does the same in giving me back 1 result being the first hit, ignoring 3 and 4.

is there a way to change this LINQ Statement to actually look through all the barcodes?

edit: the information comes from a test atm so sorry if it looks a bit weird. i added info on the xml and the filter.

also, i have found something extra on the problem if the

filter contains 1,2,3 it works. filter contains 1,2,4 it will return 1 and 2 not 4.

it seems to be breaking once it can't find a solution.

String string2Stream = String.Concat("2", Environment.NewLine, "3", Environment.NewLine, "4", Environment.NewLine, "End");
        Stream reader = new MemoryStream(ASCIIEncoding.Default.GetBytes(string2Stream));
   StreamReader read = new StreamReader( reader );
   var filter = Enumerable.Where(StreamReaderToSeq(read), x => { int temp; return int.TryParse(x, out temp); });


   var query = from p in rpa.XMLData.Elements("NEWFILE").Elements("NEWRECORD") 
               where filter.Contains(p.Element("BAR_CODE").Value)
               select new { p.Element("BAR_CODE").Value };   

Underneath the xml i deleted alot of extra stuff that shouldn't be related.

<?xml version=\"1.0\"?>
<NEWFILE>

<NEWRECORD num=\"1\"><MAILSORT></MAILSORT><BAR_CODE>1</BAR_CODE>
 </NEWRECORD> 

<NEWRECORD num=\"2\"><MAILSORT></MAILSORT><BAR_CODE>2</BAR_CODE>  
</NEWRECORD>

<NEWRECORD num=\"3\"><MAILSORT></MAILSORT><BAR_CODE>3</BAR_CODE>  
</NEWRECORD>

<NEWRECORD num=\"4\"><MAILSORT></MAILSORT><BAR_CODE>4</BAR_CODE>  
</NEWRECORD>

<NEWRECORD num=\"5\"><MAILSORT></MAILSORT><BAR_CODE>5</BAR_CODE>  
</NEWRECORD>

</NEWFILE>

Answer 1

var filter = new List<string> {"1", "2", "4"};

var query = from p in barcode.Descendants("BAR_CODE")
            where filter.Contains(p.Value)
            select p.Value;

I wasn't sure where you were going with the filter you created but I think this is a pretty safe query. It's handy because it works even if BAR_CODE is empty.

Answer 2

As an alternative answer, This shows how to make it work without contains but keeping the stream.

converted to my code it works too.

BUT why does the Contains seem to break if one fails while it works ok if you replace the stream with a List or if you replace the Contains with a JOIN. anyone kniow the answer to that?

      var query = from p in rpa.XMLData.Elements("NEWFILE").Elements("NEWRECORD") 
                join f in filter on
                    p.Element("BAR_CODE").Value equals f.ToString()                    
                select p; 

or

       var projectsMemberWorkedOn =
                    rpa.XMLData.Elements("NEWFILE").Elements("NEWRECORD")
                    .Join(filter, p => p.Element("BAR_CODE").Value, f => f.ToString(), 
                        ( p, f ) => new { p, f } ) 
                        .Select(@t => @t.p );