public void GenerateOpertions(DatabaseChanges dbChanges)
{
this._operations.Clear();
switch (dbChanges.ChangeType)
{
case ChangeType.Added:
this.CreateDatabase(dbChanges);
break;
case ChangeType.Removed:
this.DropDatabase(dbChanges);
break;
case ChangeType.Modified:
//为了保证外键的变化与表的变化不冲突，按照以下顺序生成操作：添加的表、修改的表（外键）、删除的表。
foreach (var item in dbChanges.TablesChanged.Where(t => t.ChangeType == ChangeType.Added))
{
this.GenerateOpertions(item);
}
foreach (var item in dbChanges.TablesChanged.Where(t => t.ChangeType == ChangeType.Modified))
{
this.GenerateOpertions(item);
}
foreach (var item in dbChanges.TablesChanged.Where(t => t.ChangeType == ChangeType.Removed))
{
this.GenerateOpertions(item);
}
break;
default:
break;
}
foreach (var action in this._relationActions) { action(); }
this._relationActions.Clear();
}
private Result AutoMigrate(DatabaseChanges changeSet, DateTime? maxTime = null)
{
//生成所有自动迁移操作
var auto = new AutomationMigration() { Context = this };
auto.GenerateOpertions(changeSet);
var autoMigrations = auto.Operations;
if (autoMigrations.Count > 0)
{
this.GenerateTimeId(autoMigrations, maxTime);
return this.MigrateUpBatch(autoMigrations);
}
return true;
}
private void DropDatabase(DatabaseChanges dbChanges)
{
//反向按表间的引用关系删除表。
var tables = dbChanges.OldDatabase.Tables;
for (int i = tables.Count - 1; i >= 0; i--)
{
if (!dbChanges.NewDatabase.IsIgnored(tables[i].Name))
{
this.RemoveTable(tables[i]);
}
}
//当版本号嵌入到当前数据库中时，也不支持自动 DropDatabase。
if (!Context.DbVersionProvider.IsEmbaded())
{
this.AddOperation(new DropDatabase { Database = dbChanges.OldDatabase.Name });
}
}
private void CreateDatabase(DatabaseChanges dbChanges)
{
this.AddOperation(new CreateDatabase { Database = dbChanges.NewDatabase.Name });
foreach (var table in dbChanges.NewDatabase.Tables)
{
if (!dbChanges.NewDatabase.IsIgnored(table.Name))
{
this.AddTable(table);
}
}
}