In EF6 we could do the following:
context.Set<TEntity>().Attach(entity); context.Entry(entity).Collection("NavigationProperty").Load(); Since EF Core is going "100% strictly typed", they have removed the Collection function. What should we use instead?
How do I load navigation properties for an ATTACHED entity? That is, do I have a way to invoke something like .Include() and .ThenInclude(), on an entity I have already retrieved?
Explicit Loading was added in Entity Framework Core v1.1. See Microsoft Docs
From the docs:
using (var context = new BloggingContext()) { var blog = context.Blogs .Single(b => b.BlogId == 1); context.Entry(blog) .Collection(b => b.Posts) .Load(); context.Entry(blog) .Reference(b => b.Owner) .Load(); } You have 3 methods:
1. Eager loading
e.g.
var blogs = context.Blogs .Include(blog => blog.Posts) .ToList(); 2. Explicit loading
e.g.
var blog = context.Blogs .Single(b => b.BlogId == 1); context.Posts .Where(p => p.BlogId == blog.BlogId) .Load(); 3. Lazy loading (as of EF Core 2.1)
protected override void OnConfiguring(DbContextOptionsBuilder optionsBuilder) => optionsBuilder .UseLazyLoadingProxies() .UseSqlServer(myConnectionString); You can read more about it here : Loading Related Data
Update :
You can use TrackGraph API for that use case.Here is the link : graph behavior of Add/Attach
Another link : DbSet.Add/Attach and graph behavior
See below Code,
I'm inserting data in UserRef table as well another table which we have many 2 many relationships.
public void AddUser(User user, IEnumerable<UserSecurityQuestion> securityQuestion, string password) { var userModel = _mapper.Map<User, UserRef>(user); userModel.CreateTime = DateTime.Now; userModel.UserNewsLetterMaps.ToList().ForEach(u => this._context.UserNewsLetterMaps.Add(u)); this._context.RoleRefs.Attach(new RoleRef() { RoleId = (int)user.UserRole, UserRefs = new List<UserRef> { userModel } }); userModel.ResidenceStatusRefs.ToList().ForEach(u => this._context.ResidenceStatusRefs.Attach(u)); this._context.UserRefs.Add(userModel); this.Save(); } 