Remove duplicate record in list

Question

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 ; } }

Jenith Thakkar · 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

Hamid Khan · Answer

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.

Laxmidhar Sahoo · Answer

Hi Have you try Insted of List lst = new List (); Try the bellow HasSet HashSet lst = new HashSet ();

Guest User · Answer

what is item here .

Guest User · Answer

Jenith Thakkar please implement this code my code.Please it's most important for me.

Jenith Thakkar · Answer

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

Laxmidhar Sahoo · Answer

hi Instead of List use HashSet myhash1 = new HashSet (); This not allow duplicates Thanks and regards

Dhruval Dave · Answer

Its a solution. I am not getting what exactly you want ?

Guest User · Answer

Sir please prorper solution provide this.

Dhruval Dave · Answer

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); }