How can I have custom data annotation attribute alter the Target of a migration?

Question

I want to create custom data annotation attributes in order to alter the database accordingly.
To have this custom attribute apply, I want to create a
custom MigrationOperation/SqlServerMigrationSqlGenerator in order to execute the database related changes.
Now I need to get the migration Target (SQL Server: [__MigrationHistory table].[Target]) altered so that a manual/automatic migration will recognize the custom attribute and apply the custom MigrationOperation (and its inverse operation).
How can I achieve this?
I guess custom model based conventions may have to do something with this, but I'm not sure, though.
Still people out there alive using the keyboard?
Working with SQL Server/Visual Studio/Office/Windows and their poor keyboard support they seem extinct...

Answer 1

Hello,
>>Very strange... I've altered my Configuration file according to your amendments, but still no exception is thrown. Why doesn't it throw at my machine? I don't get it ...
I am wondering if the order of the steps makes difference, my steps are follow:
With your project, I comment out the TestMigrationConfiguration and replace it with a manual generated one and register the TestSqlGenerator in it.
Then it throws the exception. I merge all separate classes to one as below which could generate the error, please have a try:
using System;
using System.Collections.Generic;
using System.Data.Entity;
using System.Data.Entity.Infrastructure.Annotations;
using System.Data.Entity.Migrations;
using System.Data.Entity.Migrations.Model;
using System.Data.Entity.Migrations.Utilities;
using System.Data.Entity.ModelConfiguration.Conventions;
using System.Data.Entity.SqlServer;
using System.Globalization;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.ComponentModel.DataAnnotations;
namespace P200150121
class Program
static void Main(string[] args)
using (MyContext ctx = new MyContext())
ctx.t1.Add(new T1() { Name = "Test" });
ctx.SaveChanges();
public class T1
public int ID { get; set; }
[Required]
[MaxLength(100)]
[Test("de-DE")]
public string Name { get; set; }
[Required]
public bool IsConfirmed { get; set; }
public class MyContext : DbContext
public DbSet<T1> t1 { get; set; }
static MyContext()
Database.SetInitializer<MyContext>(new MigrateDatabaseToLatestVersion<MyContext, Configuration>());
protected override void OnModelCreating(DbModelBuilder modelBuilder)
modelBuilder.Conventions.Add(new AttributeToColumnAnnotationConvention<TestAttribute, string>("TestAnnotation", (property, attributes) => attributes[0].CultureInfo.Name));
//internal abstract class TestMigrationConfiguration : DbConfiguration
// public TestMigrationConfiguration()
// SetMigrationSqlGenerator("System.Data.SqlClient", () => new TestSqlGenerator());
internal sealed class Configuration : DbMigrationsConfiguration<MyContext>
public Configuration()
AutomaticMigrationsEnabled = true;
SetSqlGenerator("System.Data.SqlClient", new TestSqlGenerator());
protected override void Seed(P200150121.MyContext context)
// This method will be called after migrating to the latest version.
// You can use the DbSet<T>.AddOrUpdate() helper extension method
// to avoid creating duplicate seed data. E.g.
// context.People.AddOrUpdate(
// p => p.FullName,
// new Person { FullName = "Andrew Peters" },
// new Person { FullName = "Brice Lambson" },
// new Person { FullName = "Rowan Miller" }
internal class TestSqlGenerator : SqlServerMigrationSqlGenerator
protected override void Generate(ColumnModel column, IndentedTextWriter writer)
try
AnnotationValues values = null;
System.IO.File.AppendAllText("New Text Document.txt", column.Name + " Is GetValue : " + column.Annotations.TryGetValue("TestAnnotation", out values) + "\r\n");
if (values != null)
throw new Exception(string.Format("oldValue1='{0}', newValue1='{1}'", values.OldValue, values.NewValue));
values = column.Annotations["TestAnnotation"];
throw new Exception(string.Format("oldValue1='{0}', newValue1='{1}'", values.OldValue, values.NewValue));
catch (KeyNotFoundException)
base.Generate(column, writer);
[AttributeUsage(AttributeTargets.Property)]
public class TestAttribute : Attribute
private CultureInfo _cultureInfo = CultureInfo.CurrentCulture;
public CultureInfo CultureInfo { get { return _cultureInfo; } }
public TestAttribute()
public TestAttribute(string cultureName)
_cultureInfo = new CultureInfo(cultureName);
public TestAttribute(int lcid)
_cultureInfo = new CultureInfo(lcid);
Regards.
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