Why does FirstOrDefault call SaveChanges? - winforms

Question

In the following code ConfigSetting is an entity and Db is my Context.
When I step into the following line in my debugger
ConfigSetting config = this.Db.ConfigSettings.FirstOrDefault(o => o.Name == kSiteGuid);
I find I am in the context SaveChanges event.
The database already exists so EF should not be trying to seed it.
The call stack is
SBD.Syrius.DataLayer.dll!SBD.Syrius.DataLayer.Context.SaveChanges() Line 338 C#
EntityFramework.dll!System.Data.Entity.Migrations.DbMigrator.SeedDatabase() + 0x9e bytes
EntityFramework.dll!System.Data.Entity.Migrations.Infrastructure.MigratorBase.SeedDatabase() + 0x40 bytes
EntityFramework.dll!System.Data.Entity.Migrations.DbMigrator.Upgrade(System.Collections.Generic.IEnumerable pendingMigrations, string targetMigrationId, string lastMigrationId) + 0x38c bytes
EntityFramework.dll!System.Data.Entity.Migrations.Infrastructure.MigratorBase.Upgrade(System.Collections.Generic.IEnumerable pendingMigrations, string targetMigrationId, string lastMigrationId) + 0x5e bytes
EntityFramework.dll!System.Data.Entity.Migrations.DbMigrator.Update(string targetMigration) + 0x547 bytes
EntityFramework.dll!System.Data.Entity.Migrations.Infrastructure.MigratorBase.Update() + 0x34 bytes
EntityFramework.dll!System.Data.Entity.MigrateDatabaseToLatestVersion.InitializeDatabase(SBD.Syrius.DataLayer.Context context) + 0xa3 bytes
EntityFramework.dll!System.Data.Entity.Database.SetInitializerInternal.AnonymousMethod_0(System.Data.Entity.DbContext c) + 0xd0 bytes
EntityFramework.dll!System.Data.Entity.Internal.InternalContext.PerformDatabaseInitialization.AnonymousMethod_6() + 0x55 bytes
EntityFramework.dll!System.Data.Entity.Internal.InternalContext.PerformInitializationAction(System.Action action) + 0x74 bytes
EntityFramework.dll!System.Data.Entity.Internal.InternalContext.PerformDatabaseInitialization() + 0x17d bytes
EntityFramework.dll!System.Data.Entity.Internal.LazyInternalContext.InitializeDatabase.AnonymousMethod__4(System.Data.Entity.Internal.InternalContext c) + 0x30 bytes
EntityFramework.dll!System.Data.Entity.Internal.RetryAction.PerformAction(System.Data.Entity.Internal.InternalContext input) + 0xa2 bytes
EntityFramework.dll!System.Data.Entity.Internal.LazyInternalContext.InitializeDatabaseAction(System.Action action) + 0x181 bytes
EntityFramework.dll!System.Data.Entity.Internal.LazyInternalContext.InitializeDatabase() + 0xa5 bytes
EntityFramework.dll!System.Data.Entity.Internal.InternalContext.Initialize() + 0x46 bytes
EntityFramework.dll!System.Data.Entity.Internal.InternalContext.GetEntitySetAndBaseTypeForType(System.Type entityType) + 0x2d bytes
EntityFramework.dll!System.Data.Entity.Internal.Linq.InternalSet.Initialize() + 0x97 bytes
EntityFramework.dll!System.Data.Entity.Internal.Linq.InternalSet.InternalContext.get() + 0x32 bytes
EntityFramework.dll!System.Data.Entity.Infrastructure.DbQuery.System.Linq.IQueryable.Provider.get() + 0x8c bytes
System.Core.dll!System.Linq.Queryable.FirstOrDefault(System.Linq.IQueryable source, System.Linq.Expressions.Expression> predicate) + 0x55 bytes
SBD.Syrius.DataLayer.dll!SBD.Syrius.DataLayer.DataHelper.FindOrCreateSite() Line 262 + 0x1d6 bytes C#
SBD.Syrius.UI.exe!SBD.Syrius.UI.Program.Main(string[] args) Line 34 + 0x24 bytes C#
[Native to Managed Transition]
[Managed to Native Transition]
mscorlib.dll!System.Runtime.Hosting.ApplicationActivator.CreateInstance(System.ActivationContext activationContext, string[] activationCustomData) + 0x66 bytes
Microsoft.VisualStudio.HostingProcess.Utilities.dll!Microsoft.VisualStudio.HostingProcess.HostProc.RunUsersAssemblyDebugInZone() + 0x8d bytes
mscorlib.dll!System.Threading.ExecutionContext.RunInternal(System.Threading.ExecutionContext executionContext, System.Threading.ContextCallback callback, object state, bool preserveSyncCtx) + 0x285 bytes
mscorlib.dll!System.Threading.ExecutionContext.Run(System.Threading.ExecutionContext executionContext, System.Threading.ContextCallback callback, object state, bool preserveSyncCtx) + 0x9 bytes
mscorlib.dll!System.Threading.ExecutionContext.Run(System.Threading.ExecutionContext executionContext, System.Threading.ContextCallback callback, object state) + 0x57 bytes
mscorlib.dll!System.Threading.ThreadHelper.ThreadStart() + 0x51 bytes
[Native to Managed Transition]
The Debugger shows
'SBD.Syrius.UI.vshost.exe' (Managed (v4.0.30319)): Loaded 'E:\EShared\Syrius6\syrius_syrius\SBD.Syrius.UI\bin\Debug\SBD.Syrius.Synchronisation.dll', Symbols loaded.
A first chance exception of type 'System.Data.SqlClient.SqlException' occurred in System.Data.dll
A first chance exception of type 'System.Data.SqlClient.SqlException' occurred in System.Data.dll
A first chance exception of type 'System.Data.SqlClient.SqlException' occurred in System.Data.dll
A first chance exception of type 'System.Data.EntityCommandExecutionException' occurred in System.Data.Entity.dll
A first chance exception of type 'System.Data.EntityCommandExecutionException' occurred in System.Data.Entity.dll
A first chance exception of type 'System.Data.EntityCommandExecutionException' occurred in System.Data.Entity.dll
Step into: Stepping over method without symbols 'System.Data.Entity.Infrastructure.DbContextInfo.CreateActivator.AnonymousMethod__0'
Step into: Stepping over method without symbols 'System.Data.Entity.Infrastructure.DbContextInfo.CreateInstance'
Step into: Stepping over method without symbols 'System.Data.Entity.Migrations.DbMigrator.SeedDatabase'
[update]
Information about the initializer
private static string _connectionString;
public Context()
: base(_connectionString )
{
Database.SetInitializer(new MigrateDatabaseToLatestVersion<Context, Configuration>());
}
public Context(string connString)
: base(connString)
{
_connectionString = connString;
Database.SetInitializer(new MigrateDatabaseToLatestVersion<Context, Configuration>());
}
public Context(string connString )
: base(connString)
{
_connectionString = connString;
}
For the Configuration class
namespace SBD.Syrius.DataLayer.Migrations
{
using System.Data.Entity.Migrations;
public sealed class Configuration : DbMigrationsConfiguration<SBD.Syrius.DataLayer.Context>
{
public Configuration()
{
AutomaticMigrationsEnabled = false;
}
protected override void Seed(SBD.Syrius.DataLayer.Context context)
{
}
}
}

Answer 1

If you look at the call stack, you can see that it's going through a database migration. This is the process that occurs when you make a change to your model, and the database structure needs to be updated.
After the migration occurs, EF then calls SeedDatabase, which allows you to add default values. At the end of SeedDatabase, it calls SaveChanges to save those changes.

Answer 2

This exception was called in the GenericRepository.cs for my UnitOfWork when I tried to create a new entity.
public virtual void Insert(TEntity entity)
{
dbSet.Add(entity);
}
Easy Fix
In the Package Manager Console. Add a new migration Add-Migration SomeMeaninglessName and updated the database Update-Database.