entity-framework - 如何首先在实体框架代码中使用 MigratorScriptingDecorator？

Question

我在使用MigratorScriptingDecorator.ScriptUpdateEntity Framework 4.3.1 时遇到问题。

当指定 sourceMigration 和 targetMigration 时，只有我的初始迁移被写入，其余的迁移变为空。

我在 Microsoft Connect 上输入了包含重现代码的错误报告。 https://connect.microsoft.com/VisualStudio/feedback/details/731111/migratorscriptingdecorator-in-entity-framework-migrations-does-not-respect-sourcemigration-and-targetmigration

我希望MigratorScriptingDecorator.ScriptUpdate("from", "to")行为与相应的 PM 命令完全相同

PM> Update-Database -Script -SourceMigration from -TargetMigration to

ScriptUpdate 是否应该等同于Update-Database -Script？
还有其他从代码生成更新脚本的方法吗？

Answer 1

正如在链接的 Microsoft Connect 问题上所指出的那样，问题是DbMigrator在几个MigratorScriptingDecorators 上重复使用相同的问题。

原始代码是

DbMigrator efMigrator = new DbMigrator(new Configuration());
var pendingMigrations = efMigrator.GetLocalMigrations().ToList();
pendingMigrations.Insert(0, "0");
foreach (var migration in pendingMigrations.Zip(pendingMigrations.Skip(1), Tuple.Create))
{
    var sql = new MigratorScriptingDecorator(efMigrator).ScriptUpdate(migration.Item1, migration.Item2); // <-- problem here, the efMigrator is reused several times
    Console.WriteLine("Migration from " + (migration.Item1 ?? "<null> ") + " to " + (migration.Item2 ?? "<null> "));
    Console.WriteLine(sql);
    Console.WriteLine("-------------------------------------");
}

MigratorScriptingDecorator应该像这样在循环外实例化：

DbMigrator efMigrator = new DbMigrator(new Configuration());
var pendingMigrations = efMigrator.GetLocalMigrations().ToList();
pendingMigrations.Insert(0, "0");
var scriptMigrator = new MigratorScriptingDecorator(efMigrator); // <-- now only one MigratorScriptingDecorator is created for the DbMigrator
foreach (var migration in pendingMigrations.Zip(pendingMigrations.Skip(1), Tuple.Create))
{
    var sql = scriptMigrator.ScriptUpdate(migration.Item1, migration.Item2);
    Console.WriteLine("Migration from " + (migration.Item1 ?? "<null> ") + " to " + (migration.Item2 ?? "<null> "));
    Console.WriteLine(sql);
    Console.WriteLine("-------------------------------------");
}