EF 4.3.1 Migration Exception - AlterColumn defaultValueSql creates same default constraint name for different tables

Question

I have a DB that I created using the OOB database initializer, and I am using Code First with EF 4.3.1.

I wanted to take advantage of the new \"IgnoreChanges\" flag

Answer 1

Ok, based on nemesv's answer (accepted), here's how I ended up fixing the problem for now, until a fix is officially issued:

internal class MyFixedSqlServerMigrationSqlGenerator : SqlServerMigrationSqlGenerator
{
    protected override void Generate(AlterColumnOperation alterColumnOperation)
    {
        if (alterColumnOperation == null)
            throw new ApplicationException("alterColumnOperation != null");

        ColumnModel column = alterColumnOperation.Column;
        if ((column.DefaultValue != null) || !string.IsNullOrWhiteSpace(column.DefaultValueSql))
        {
            using (IndentedTextWriter writer = Writer())
            {
                writer.Write("ALTER TABLE ");
                writer.Write(this.Name(alterColumnOperation.Table));
                writer.Write(" ADD CONSTRAINT DF_");
                writer.Write(alterColumnOperation.Table + "_"); //   <== THIS IS THE LINE THAT FIXES THE PROBLEM
                writer.Write(column.Name);
                writer.Write(" DEFAULT ");
                writer.Write(column.DefaultValue != null ? base.Generate(column.DefaultValue) : column.DefaultValueSql);
                writer.Write(" FOR ");
                writer.Write(this.Quote(column.Name));
                this.Statement(writer);
            }
        }
        using (IndentedTextWriter writer2 = Writer())
        {
            writer2.Write("ALTER TABLE ");
            writer2.Write(this.Name(alterColumnOperation.Table));
            writer2.Write(" ALTER COLUMN ");
            writer2.Write(this.Quote(column.Name));
            writer2.Write(" ");
            writer2.Write(this.BuildColumnType(column));
            if (column.IsNullable.HasValue && !column.IsNullable.Value)
            {
                writer2.Write(" NOT NULL");
            }
            this.Statement(writer2);
        }
    }
}


internal sealed class Configuration : DbMigrationsConfiguration
{
    public Configuration()
    {
        AutomaticMigrationsEnabled = true;

        SetSqlGenerator("System.Data.SqlClient", new MyFixedSqlServerMigrationSqlGenerator());
    }
    ...
}