Cannot SaveChanges() with DbContext Entity Framework Core

Question

I am relatively new to EF core, so bare with me.

I am trying to create an application using the database-first approach (as code first did not work either) using Entity Framework Core. I have reverse engineered all the models using EF Core successfully, but upon trying to add new items to the database using my DbContext, I get a view nested exception message. My application utilizes two many to many relationships.

I am able to add singular items into the database, the problem arises with adding items into junction tables

The error occurs after

ctx.Usergorups.Add(newusergroup)

at

ctx.SaveChanges();

and all following Add() statements:

Microsoft.EntityFrameworkCore.Infrastructure.IInfrastructure<System.IServiceProvider>.Instance '((Microsoft.EntityFrameworkCore.Infrastructure.IInfrastructure<System.IServiceProvider>)ctx.Usergroups).Instance' threw an exception of type 'System.NotImplementedException' System.IServiceProvider {System.NotImplementedException}

Spot where error occurs:

private void Create_Group(object sender, RoutedEventArgs e)
{
    string groupname = this.namebox.Text;

    if (groupname.Equals("Enter user friendly name") || (groupname.Equals("")))
    {
        MessageBox.Show("The group name cannot be the default. Enter something something descriptive");
        return;
    }
    else
    {
        try
        {
            List<UserUserGroup> usergroups = new List<UserUserGroup>();
            List<AccessGroupUserGroup> Accessgroupers = new List<AccessGroupUserGroup>();
            Usergroups newusergroup = new Usergroups()
                {
                    Name = groupname
                };

            var ctx = new FMS_SIRContext();

            ctx.Usergroups.Add(newusergroup);
            ctx.SaveChanges();

            foreach (Users u in this.members.Where(u => u != null))
            {
                usergroups.Add(new UserUserGroup()
                    {
                        UserId = u.Id,
                        User = u,
                        UserGroupId = newusergroup.Id,
                        UserGroup = newusergroup
                    });
            }

            ctx.UserUserGroup.AddRange(usergroups);

            foreach (Accessgroups a in this.acceessGroups.Where(a => a != null))
            {
                Accessgroupers.Add(new AccessGroupUserGroup()
                    {
                        AccessGroup = a,
                        AccessGroupId = a.Id,
                        UserGroup = newusergroup,
                        UserGroupId = newusergroup.Id
                    });
            }

            ctx.AccessGroupUserGroup.AddRange(Accessgroupers);
            ctx.SaveChanges();

            this.Close();
        }
        catch (Exception s)
        {
            MessageBox.Show(s.Data.ToString());
        }
    }
}

My DbContext class:

public partial class FMS_SIRContext : DbContext
{
    public FMS_SIRContext()
    {
    }

    public FMS_SIRContext(DbContextOptions<FMS_SIRContext> options)
        : base(options)
    {
        this.ChangeTracker.LazyLoadingEnabled = false;
    }

    public virtual DbSet<AccessGroupUserGroup> AccessGroupUserGroup { get; set; }
    public virtual DbSet<Accessgroups> Accessgroups { get; set; }
    public virtual DbSet<UserUserGroup> UserUserGroup { get; set; }
    public virtual DbSet<Usergroups> Usergroups { get; set; }
    public virtual DbSet<Users> Users { get; set; }

    protected override void OnConfiguring(DbContextOptionsBuilder optionsBuilder)
    {
        if (!optionsBuilder.IsConfigured)
        {
            optionsBuilder.UseSqlServer("Data Source=az18w7413;Initial Catalog=****;Persist Security Info=True;User ID=******;Password=******;");
        }
    }

    protected override void OnModelCreating(ModelBuilder modelBuilder)
    {
        modelBuilder.Entity<AccessGroupUserGroup>(entity =>
        {
            entity.HasKey(e => new { e.AccessGroupId, e.UserGroupId });

            entity.ToTable("AccessGroupUserGroup", "asps");
            entity.HasIndex(e => e.UserGroupId);

            entity.Property(e => e.AccessGroupId).HasColumnName("AccessGroupID");
            entity.Property(e => e.UserGroupId).HasColumnName("UserGroupID");

            entity.HasOne(d => d.AccessGroup)
                .WithMany(p => p.AccessGroupUserGroup)
                .HasForeignKey(d => d.AccessGroupId);

            entity.HasOne(d => d.UserGroup)
                .WithMany(p => p.AccessGroupUserGroup)
                .HasForeignKey(d => d.UserGroupId);
        });

        modelBuilder.Entity<Accessgroups>(entity =>
        {
            entity.ToTable("accessgroups", "asps");

            entity.Property(e => e.Id).HasColumnName("ID");
            entity.Property(e => e.Itname).HasColumnName("ITNAME");
            entity.Property(e => e.Name).HasColumnName("NAME");
            entity.Property(e => e.Permission).HasColumnName("PERMISSION");
        });

        modelBuilder.Entity<UserUserGroup>(entity =>
        {
            entity.HasKey(e => new { e.UserId, e.UserGroupId });

            entity.ToTable("UserUserGroup", "asps");
            entity.HasIndex(e => e.UserGroupId);

            entity.Property(e => e.UserId).HasColumnName("UserID");
            entity.Property(e => e.UserGroupId).HasColumnName("UserGroupID");

            entity.HasOne(d => d.UserGroup)
                .WithMany(p => p.UserUserGroup)
                .HasForeignKey(d => d.UserGroupId);

            entity.HasOne(d => d.User)
                .WithMany(p => p.UserUserGroup)
                .HasForeignKey(d => d.UserId)
                .OnDelete(DeleteBehavior.ClientSetNull)
                .HasConstraintName("FK_UserUserGroup_User");
        });

        modelBuilder.Entity<Usergroups>(entity =>
        {
            entity.ToTable("usergroups", "asps");

            entity.Property(e => e.Id).HasColumnName("ID");
            entity.Property(e => e.Name).HasColumnName("NAME");
        });

        modelBuilder.Entity<Users>(entity =>
        {
            entity.ToTable("Users", "asps");

            entity.HasIndex(e => e.Eid)
                .HasName("IX_EID")
                .IsUnique();

            entity.HasIndex(e => e.Id)
                .HasName("IX_ID");

            entity.Property(e => e.Id).HasColumnName("ID");
            entity.Property(e => e.Eid)
                .HasColumnName("EID")
                .HasMaxLength(50);
            entity.Property(e => e.FirstName).HasMaxLength(100);
            entity.Property(e => e.LastName).HasMaxLength(100);
            entity.Property(e => e.LocationId).HasColumnName("LocationID");
            entity.Property(e => e.Mail).HasMaxLength(200);
        });

        OnModelCreatingPartial(modelBuilder);
    }

    partial void OnModelCreatingPartial(ModelBuilder modelBuilder);
}

Answer 1

I got a very similar error when I was working on a DbContext in EF Core and it was because I did not save my context after adding related data and not saving, which had a domino effect. I had updated two tables and since one was dependent on the other, the save failed. When you have dependent data, you need to add the dependency, save changes, and then add the new dependent data.

Answer 2

I finally figured it out (8 hours later). It was not a dependency injection problem, but rather a ID assignment error. I assigned the ID of user, usergroup, accessgroup, and usergroup as well as assigned the objects, therefor making the ids 0 from the default constructor.

private void Create_Group(object sender, RoutedEventArgs e)
        {
            string groupname = this.namebox.Text;
            if (groupname.Equals("Enter user friendly name") || (groupname.Equals("")))
            {
                MessageBox.Show("The group name cannot be the default. Enter something something descriptive");
                return;
            }
            else
            {
                try
                {
                    List<UserUserGroup> usergroups = new List<UserUserGroup>();
                    List<AccessGroupUserGroup> Accessgroupers = new List<AccessGroupUserGroup>();
                    Usergroups newusergroup = new Usergroups()
                    {
                        Name = groupname
                    };
                    FMS_SIRContext ctx = new FMS_SIRContext();
                    ctx.Usergroups.Add(newusergroup);
                    ctx.SaveChanges();
                    foreach (Users u in members.Where(u => u != null))
                    {
                        usergroups.Add(new UserUserGroup()
                        {
                           UserId = u.Id,
                            //User = u,
                            UserGroupId = newusergroup.Id,
                            //UserGroup = newusergroup
                        });
                    }
                    //ctx.Usergroups.Add(newusergroup);
                    ctx.AddRange(usergroups);
                    foreach (Accessgroups a in this.acceessGroups.Where(a => a != null))
                    {
                        Accessgroupers.Add(new AccessGroupUserGroup()
                        {
                            //AccessGroup = a,
                            AccessGroupId = a.Id,
                            //UserGroup = newusergroup,
                            UserGroupId = newusergroup.Id
                        });
                    }
                    ctx.AddRange(Accessgroupers);
                    ctx.SaveChanges();
                    this.Close();
                }
                catch (Exception s)
                {
                    MessageBox.Show(s.Data.ToString());
                }
            }

        }