senrecep/csharpessentials/csharpessentials-clone

dotnet add package CSharpEssentials.Clone

using CSharpEssentials.Clone;

public class Product : ICloneable<Product>
{
    public int Id       { get; init; }
    public string Name  { get; init; } = "";
    public List<Tag> Tags { get; init; } = new();
 
    public Product Clone() => new()
    {
        Id   = Id,
        Name = Name,
        Tags = Tags.Select(t => t.Clone()).ToList()  // deep-copy child collections too
    };
}
 
public class Tag : ICloneable<Tag>
{
    public string Value { get; init; } = "";
    public Tag Clone() => new() { Value = Value };
}

List<Product> products = [new() { Id = 1, Name = "Pen" }];
 
// IEnumerable<T> where T : ICloneable<T>: lazily clones each element
IEnumerable<Product> copies = products.Clone();
 
// IQueryable<T> where T : ICloneable<T>: clones in memory, not translated to SQL
IQueryable<Product> projected = products.AsQueryable().Clone();

List<Product> snapshot = await db.Products
    .Where(p => p.Name.StartsWith("P"))
    .ToListAsync();
 
List<Product> working = snapshot.Clone().ToList();  // independent deep copies; mutations don't affect EF tracking