How to validate a duplicate value in the list object using C#?

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I want to validate a duplicate value in the list object using c#. i am parsing xml string with multiple nodes and setting to a list object
I am looping through the list object after assigning the xml node values.
while doing so i need to show validation message if a Ref No is duplicated based on the row count
I am always getting reference no: duplicate message.

What I have tried:

My xml node is as below:

XML

<OriginatorRegistrationRequest>
    <HEADER>
        <Contract_Ref_No>4092</Contract_Ref_No>
        <Source>UTIL</Source>
    </HEADER>
    <BODY>
        <OriginatorDetails>
            <Ref_No>14492</Ref_No>
          </OriginatorDetails>
         <OriginatorDetails>
            <Ref_No>14492</Ref_No>
          </OriginatorDetails>
     </BODY>
</OriginatorRegistrationRequest>

Code tried is as below:

C#

public List<OUT_200_DETAIL> objOUT_200_DETAIL { get; set; }
foreach (OUT_200_DETAIL objOUT_200_DETAIL in objOUT_200_CONTROL.objOUT_200_DETAIL)
{
    if (objOUT_200_CONTROL.objOUT_200_DETAIL[index].RefNo.Contains(objOUT_200_DETAIL.RefNo.Trim()))
    {
        Error += Environment.NewLine + "Row " + Count + "-Reference No: already exists";
    }
}

Posted 9-Sep-21 23:47pm

ranio

Updated 10-Sep-21 3:43am

PIEBALDconsult

v5

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Comments

CHill60 10-Sep-21 5:50am

You forgot to put any code in your loop

Richard MacCutchan 10-Sep-21 5:57am

FOREACH item in XML_NODES
BEGIN
    IF LIST contains item.refno
        PRINT "validation message
    ELSE
        ADD item.refno to LIST
END

PIEBALDconsult 10-Sep-21 9:44am

Aren't you matching each node to itself? Or always matching against the first?

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OriginalGriff · Answer 1 · 2021-09-10T02:35:00

Why not just use Linq methods?

C#

public class MyClass
    {
    public int Id { get; set; }
    public string Name { get; set; }
    public override string ToString()
        {
        return $"ID: {Id}, Name: \"{Name}\"";
        }
    }

C#

List<MyClass> items = new List<MyClass>();
items.Add(new MyClass() { Id = 1, Name = "One" });
items.Add(new MyClass() { Id = 2, Name = "Two" });
items.Add(new MyClass() { Id = 2, Name = "Two Again" });
items.Add(new MyClass() { Id = 1, Name = "One Again" });
items.Add(new MyClass() { Id = 3, Name = "Three" });
var duplicates = items.GroupBy(x => x.Id).SelectMany(g => g.Skip(1));
Console.WriteLine($"Duplicates exist:\n   {string.Join("\n   ", duplicates)}");

Run that, and you get a list of duplicates:

Duplicates exist:
   ID: 1, Name: "One Again"
   ID: 2, Name: "Two Again"