I have 2 classes

 public class Product
    {
        public DateTime Date { get; set; }
        public string Name { get; set; }
        public int Amount { get; set; }
    }


public class Campaign
    {
        public long CampaignId { get; set; }
        public string CampaignName { get; set; }            
        public List<Product> Products { get; set; }
    }

var campaign = new Campaign();
                campaign.CampaignId = Item.CampaignId;
                campaign.CampaignId = Item.CampaignId;
                campaign.CampaignName = Item.CampaignName;                    
                campaign.Products = productList;


                campaignList.Add(campaign);

                productList.Clear();

When I productList.Clear() my "campaign" deletes it's "campaign.Products"

how can I preserve it?

CodePudding user response：

campaign.Products = new List<Product>(productList);

CodePudding user response：

because campaign.Products is the same reference of productList
they are both pointing to the same list , any action on one will be reflected in the other varialbe
you need to clone (make another copy of the list) by different ways as follwoing

campaign.Products = productList.GetClone();

or

campaign.Products = productList.ToList();  

or

campaign.Products.AddRange(productList);

check the following url

https://www.techiedelight.com/clone-list-in-csharp/