public MigrationGenerator(NHibernate.Cfg.Configuration configuration, Encoding encoding)
{
this.Encoding = encoding;
Configuration = configuration;
Configuration.BuildMappings(); // necessary to complete columns creation (foreign keys...)
var mapping = Configuration.CreateMappings(new GenericDialect());
// extract the tables scheme
CurrentScheme = new MigrationScheme(mapping.IterateTables.Select(t => new MigrationTable(t)));
UpdateForeignKeys();
PreviousSnapshotFileName = string.Format("{0}\\previous.snapshot",Directory.GetCurrentDirectory());
}
public IEnumerable<Migration> CompareScheme(MigrationScheme previous, MigrationScheme current)
{
// detect new tables
foreach (var table in current.Tables)
{
if (!previous.HasTable(table.Name))
{
yield return new CreateTableMigration(table);
}
else // table still exists
{
var previous_table = previous[table.Name];
foreach (var column in table.Columns)
{
var previous_column = previous_table.Columns.FirstOrDefault(c => c.Name == column.Name);
if (previous_column == null) //detect new columns
{
yield return new CreateColumnMigration(column);
}
else
{
// column alteration
if (!previous_column.IsSimilarTo(column))
yield return new AlterColumnMigration(previous_column, column);
}
}
// delect deleted columns
foreach (var previous_column in previous_table.Columns)
{
var column = table.Columns.FirstOrDefault(c => c.Name == previous_column.Name);
if (column == null)
{ // column was deleted
yield return new DeleteColumnMigration(previous_column);
}
}
}
}
// detect droped tables
foreach (var table in previous.Tables)
{
if (!current.HasTable(table.Name))
{
yield return new DropTableMigration(table);
}
}
}
