How To Delete Duplicate Records From Two Lists ?

Question

1.00/5 (2 votes)

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Class-->

C#

public class DocumentsLists
   {
       public int DocumentId { get; set; }
       public string DocumentName { get; set; }
   }

List-->

C#

var ChkDocumentData = new List<documentslists>();
var AppDocData = new List<documentslists>();

Contents of two list-->

ChkDocumentData contains:

C#

 {
   {DocumentId = 42, DocumentName ="Passport"},
   {DocumentId = 44, DocumentName ="Adhar Card"},
   {DocumentId = 45, DocumentName ="Driving License"},
   {DocumentId = 46, DocumentName ="Voter ICard"}
};

AppDocData contains :

C#

{DocumentId = 44, DocumentName ="Adhar Card"};

I want a list Contains :

C#

{
   {DocumentId = 42, DocumentName ="Passport"},
   {DocumentId = 45, DocumentName ="Driving License"},
   {DocumentId = 46, DocumentName ="Voter ICard"}
};

Thanks in advance

Posted 29-Oct-15 20:48pm

ARYA JAGANNATH

Updated 29-Oct-15 21:05pm

Maciej Los

v4

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Comments

Sergey Alexandrovich Kryukov 30-Oct-15 2:57am

Why not preventing duplicates in first place, when you add data?
—SA

phil.o 30-Oct-15 3:10am

Your DocumentsLists class obviously represents a single document. So why naming it with a List suffix, and why the plural?
Semantically, that is plain wrong, and error prone.

4 solutions

Solution 1

See this : https://msdn.microsoft.com/en-us/library/vstudio/bb300779(v=vs.100).aspx[^]

Another way

C#

var result = ChkDocumentData.Where(x => !AppDocData.Any(y => x.DocumentId == y.DocumentId));

Reference : http://stackoverflow.com/a/5636511[^]

Regards..

Posted 29-Oct-15 20:53pm

Thanks7872

Updated 29-Oct-15 21:24pm

v3

Comments

Maciej Los 30-Oct-15 3:02am

5ed!

Thanks7872 30-Oct-15 3:11am

Thnaks Maciej.

ARYA JAGANNATH 30-Oct-15 3:05am

I Used
IEnumerable<documentslists> onlyInFirstSet = ChkDocumentData.Except(AppDocData);

But Still It Returns
{
{DocumentId = 42, DocumentName ="Passport"},
{DocumentId = 44, DocumentName ="Adhar Card"},
{DocumentId = 45, DocumentName ="Driving License"},
{DocumentId = 46, DocumentName ="Voter ICard"}
};

Thanks7872 30-Oct-15 3:23am

See updated solution for code block.

Solution 4

As Rohan Leuva[^] mentioned, the simplest way is to use Except method:

C#

var resultList = ChkDocumentData.Except(AppDocData);

As Sergey Alexandrovich Kryukov[^] suggests in the comment to the question, you can use Contains[^] method to avoid duplicates during the process of adding data to the list.

C#

if(!ChkDocumentData.Contains(SomeDocument))
{
    ChkDocumentData.Add(SomeDocument);
}

But the best way is to create custom class collection and provide Add method which can handle such of functionality (avoiding duplicates). See: Walkthrough: Creating Your Own Collection Class[^]

C#

public class DocumentsCollection : CollectionBase
{
   public void Add(DocumentList dl)
    {
        if (!List.Contains(dl))
        {
             List.Add(dl);
        }
    }
}

Posted 29-Oct-15 21:20pm

Maciej Los

v2

Comments

Thanks7872 30-Oct-15 3:25am

Well explained. +5!

Maciej Los 30-Oct-15 3:33am

Thank you, Rohan.

Solution 5

IEnumerable<int> documentIds = ChkDocumentData.Select(c => c.DocumentId).Except(AppDocData.Select(c => c.DocumentId));
IEnumerable<documentslists> result = ChkDocumentData.Where(c => documentIds.Contains(c.DocumentId));

Posted 29-Oct-15 23:20pm

Manoj Panja

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Krunal Rohit · Accepted Answer · 2015-10-29T21:10:00

Solution 3

Try this,

C#

var result = ChkDocumentData.Where(c => !AppDocData.Any(a => a.DocumentId == c.DocumentId)).ToList();

-KR

Posted 29-Oct-15 21:10pm

Krunal Rohit

Comments

ARYA JAGANNATH 30-Oct-15 3:15am

Many Many Thanks !

Krunal Rohit 30-Oct-15 3:31am

Did it solve your issue ?

-KR