I have a simple ExternalAccount entity:

namespace Domain
{
    public class ExternalAccount
    {
        public Guid Id { get; set; }

        public string APIKey { get; set; }
    }
}

and an AppUser entity that has a one-to-many relationship with the ExternalAccount

using Microsoft.AspNetCore.Identity;

namespace Domain
{
    public class AppUser : IdentityUser
    {
        public ICollection<ExternalAccount> ExternalAccounts { get; set; } = new List<ExternalAccount>();
    }
}

My DataContext class is also pretty straightforward:

using Domain;
using Microsoft.AspNetCore.Identity.EntityFrameworkCore;
using Microsoft.EntityFrameworkCore;

namespace Persistence
{
    public class DataContext : IdentityDbContext<AppUser>
    {
        public DataContext(DbContextOptions options) : base(options)
        {

        }

        public DbSet<ExternalAccount> ExternalAccounts { get; set; }
    }
}

Now for simplicity I have a method that contains the following:

var user = await _context.Users.Include(p => p.ExternalAccounts).FirstOrDefaultAsync(x => x.UserName == "Bob");

if (user == null) return null;

ExternalAccount account = new ExternalAccount
{
    Id = "08186b29-e603-4cc8-9575-47b237775274",
    APIKey = "some long text here",
};

user.ExternalAccounts.Add(account);

var result = await _context.SaveChangesAsync() > 0;

After hitting the last line I'm getting a

"statusCode": 500,
"message": "The database operation was expected to affect 1 row(s), but actually affected 0 row(s); data may have been modified or deleted since entities were loaded. See http://go.microsoft.com/fwlink/?LinkId=527962 for information on understanding and handling optimistic concurrency exceptions.",

While debugging if I hover over user.ExternalAccounts.Add(account); it looks like the account has been added.

Any idea what could be the problem here?

CodePudding user response：

Before saving your changes in your dbcontext, you need to update the users table:

await _context.Users.Update(user);

Call the above-mentioned piece before SaveChangesAsync() attempt.

CodePudding user response：

Your class ExternalAccount might need a reference to the AppUser class:

namespace Domain
{
    public class ExternalAccount
    {
        public Guid Id { get; set; }

        public string APIKey { get; set; }
        
        public int UserId { get; set; }
   
        public virtual AppUser User { get; set; }

    }
}

Then you can map it inside your dbcontext:

modelBuilder.Entity<ExternalAccount>(entity =>
        {
            entity.HasOne(ea => ea.User)
               .WithMany(u => u.ExternalAccount)
               .HasForeignKey(ea => ea.UserId);
        });