private async Task <IEnumerable <OperationsMigration> > LoadMirationsAsync(IDataMigration instance, int version)
{
var type = instance.GetType();
var migration = instance as DataMigration;
if (migration != null)
{
InitDataMigration(migration);
}
var dbMigration = await _reposority.FindMigrationAsync(type.FullName);
if ((dbMigration == null && version == -1) || //卸载
(dbMigration != null && dbMigration.Version == version)) //版本已经是设置的版本
{
return(null);
}
if (version == 0) //安装版本设为最大值
{
version = int.MaxValue;
}
if (dbMigration == null || version > dbMigration.Version)
{
return(Upgrade(migration, dbMigration, version));
}
if (dbMigration.Version > version)
{
return(Downgrade(migration, dbMigration, version));
}
return(null);
}