Remove duplicate record in list

6y1kLearn iOS Programming

I have get record by id. It's API run successfully. But i have face issue same record get multiple time

public SupplementResponse GetSupplementsList(SupplemetParam obj_parameter)
{
SupplementResponse obj_result = new SupplementResponse();
List lst = new List();
var PDFURL = new ConfigurationBuilder().AddJsonFile("appsettings.json").Build().GetSection("AppSettings")["SupplementUrl"];
try
{
var matchingdata = (from c in _context.TblSupplementDetail
join sc in _context.SupplementMaster on c.SupplementId equals sc.SupplementId
where c.UserId == obj_parameter.UserId
select new
{
sc.SupplementId,
sc.SupplementType,
sc.SupplementPdf,
c.SupplementStatus
}).ToList();
if (matchingdata.Count > 0)
{
foreach (var item in matchingdata)
{
SupplementListDetail obj_supplement = new SupplementListDetail();
obj_supplement.SupplementsId = item.SupplementId;
obj_supplement.SupplementType = item.SupplementType;
obj_supplement.SupplementPDF = PDFURL + "" + item.SupplementPdf;
obj_supplement.SupplementStatus = Convert.ToInt32(item.SupplementStatus);
lst.Add(obj_supplement);
}
}
var Supplement_List = _context.SupplementMaster.ToList();
{
if(Supplement_List .Count >0)
{
foreach (var item in Supplement_List)
{
if(item.SupplementStatus==false)
{
SupplementListDetail obj_supplement = new SupplementListDetail();
obj_supplement.SupplementsId = item.SupplementId;
obj_supplement.SupplementType = item.SupplementType;
obj_supplement.SupplementPDF = PDFURL + "" + item.SupplementPdf;
obj_supplement.SupplementStatus = Convert.ToInt32(item.SupplementStatus);
lst.Add(obj_supplement);
}
}
}
}
obj_result.Response = 1;
obj_result.ErrorMessage = "No Error Found";
List uniqueLst = lst.Distinct().ToList(); //i have use this here.
obj_result.lst_Supplement = uniqueLst;
It's me classes.
public class SupplemetParam
{
public int UserId { get; set; }
}
public class SupplementResponse
{
public int Response { get; set; }
public string ErrorMessage { get; set; }
public IEnumerable lst_Supplement { get; set; }
}
public class SupplementListDetail
{
public int SupplementsId { get; set; }
public string SupplementType { get; set; }
public string SupplementPDF { get; set; }
public int SupplementStatus { get; set; }
}

10 Replies

Know the answer? Post it — somebody with the same question will find it here.

Jenith Thakkar6y ago
Accepted answer
Okay let me change it as per your code
class DistinctItemComparer : IEqualityComparer {

    public bool Equals(SupplementListDetail x, SupplementListDetail y) {
        return x.SupplementsId  == y.SupplementsId &&
            x.SupplementType == y.SupplementType &&
            x.SupplementPDF == y.SupplementPDF &&
            x.SupplementStatus == y.SupplementStatus;
    }

    public int GetHashCode(SupplementListDetail obj) {
        return obj.SupplementsId.GetHashCode() ^
            obj.SupplementType.GetHashCode() ^
            obj.SupplementPDF.GetHashCode() ^
            obj.SupplementStatus.GetHashCode();
    }
}
Add above class
List uniqueLst = lst.Distinct(new DistinctItemComparer()).ToList();
Use it like this
+5
Hamid Khan6y ago
Hi Sourabh,

You could use ConcurrentDictionary

Please follow this link for more details:

https://docs.microsoft.com/en-us/dotnet/standard/collections/thread-safe/how-to-add-and-remove-items#:~:text=ConcurrentDictionary%20is,same%20key%20a%20new%20value.
+1
Laxmidhar Sahoo6y ago
Hi

Have you try
Insted of List lst = new List();
Try the bellow HasSet
HashSet lst = new HashSet();
+1
6y ago
what is item here .
+1
6y ago
Jenith Thakkar please implement this code my code.Please it's most important for me.
+1
Jenith Thakkar6y ago
Hi Sourabh
Still you're looking for the answer? or have you find it

If you still looking for then you can do it like this way
Create a custom class of distinct
class DistinctItemComparer : IEqualityComparer {

    public bool Equals(Item x, Item y) {
        return x.Id == y.Id &&
            x.Name == y.Name &&
            x.Code == y.Code &&
            x.Price == y.Price;
    }

    public int GetHashCode(Item obj) {
        return obj.Id.GetHashCode() ^
            obj.Name.GetHashCode() ^
            obj.Code.GetHashCode() ^
            obj.Price.GetHashCode();
    }
}
In place of this (Id, Name, Code, Price you take your field names
var distinctItems = items.Distinct(new DistinctItemComparer());
Then you can use it like these way so it will provide you perfect result
Thank you
+1
Laxmidhar Sahoo6y ago
hi

Instead of List use

HashSet myhash1 = new HashSet();

This not allow duplicates

Thanks and regards
+1
Dhruval Dave6y ago
Its a solution. I am not getting what exactly you want ?
+1
6y ago
Sir please prorper solution provide this.
+1
Dhruval Dave6y ago
Hey Sourabh,

According to me you can try with creating an extension method based on the respective property to remove the duplicates. For example please check below method:
public static IEnumerable DistinctBy
(this IEnumerable source, Func keySelector)
{
HashSet seenKeys = new HashSet();
foreach (TSource element in source)
{
if (seenKeys.Add(keySelector(element)))
{
yield return element;
}
}
}

And later you can use this extension method like:

var query = lst.DistinctBy(p => p.Id);
var query = lst.DistinctBy(p => p.Id);

Also, If you are not interested to introduce an another set of overhead with this extension method, You can also check that respective ID is exist in your list or not. If an item with specific ID is exists then simply dont add it to your list.

foreach (var item in matchingdata)
{
SupplementListDetail obj_supplement = new SupplementListDetail();
obj_supplement.SupplementsId = item.SupplementId;
obj_supplement.SupplementType = item.SupplementType;
obj_supplement.SupplementPDF = PDFURL + "" + item.SupplementPdf;
obj_supplement.SupplementStatus = Convert.ToInt32(item.SupplementStatus);

//Check here if specific ID is exists in your lst,
//If Yes then do nothing
//else add item to your list
  -- lst.Add(obj_supplement);
}
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