SaveChanges抛出System.Data.Entity.Core.EntityException

Question

I'm having an issue trying to update the AspNetUsers database in MVC 5 with ASP.NET.

I'm trying to change a value in the user, Credits, which is stored in the database defined as Models.UserDB2.AspNetUsers .

However, when I attempt this, I get thrown this error.

A first chance exception of type 'System.Data.Entity.Core.EntityException' occurred in EntityFramework.SqlServer.dll FATAL ERROR: An error occurred while starting a transaction on the provider connection. See the inner exception for details.`

Inner exception:

A first chance exception of type 'System.Data.Entity.Core.EntityException' occurred in EntityFramework.SqlServer.dll is the inner exception

This is the code causing the error.

if(player != null) {
    foreach(Models.Item item in itemDB.Items) {
        if(item.UserAssetOptionId == id) {
            if(!item.Owner.ToLower().Equals(username.ToLower())) {
                return Content("false");
            } else {
                item.Owner = "HomeguardDev";
                item.InMarket = true;
                player.Credits += item.Value / 10;
                try {
                    itemDB.SaveChanges();
                    userDB2.SaveChanges();
                    return Content("true");
                } catch(Exception e) {
                    Debug.WriteLine("FATAL ERROR: " + e.Message);
                    return Content("false");
                }
            }
        }
    }
}

The database updates fine if I only update the itemDB database, but I need to update the Credits value as well!

The model is updated with the latest schema with the database, so no problems there.

Anyone know what's up?

Answer 1

The problem is that you're trying to save the changes to itemDB while you're still iterating itemDB.Items , try to change your code to:

if (player != null) {
    foreach(Models.Item item in itemDB.Items) {
        if (item.UserAssetOptionId == id) {
            if (!item.Owner.ToLower().Equals(username.ToLower())) {
                return Content("false");
            } else {
                item.Owner = "HomeguardDev";
                item.InMarket = true;
                player.Credits += item.Value / 10;
                break;
            }
        }
    }
    try {
        itemDB.SaveChanges();
        userDB2.SaveChanges();
        return Content("true");
    } catch (Exception e) {
        Debug.WriteLine("FATAL ERROR: " + e.Message);
        return Content("false");
    }
}

As long as you're in the foreach , you can't start a second transaction.