我有两个表Factorys和Products，每个Factory可以有大量的Products，所以lazy = dynamic已被应用。
<?php
return [
/*
|--------------------------------------------------------------------------
| Default Session Driver
|--------------------------------------------------------------------------
|
| This option controls the default session "driver" that will be used on
| requests. By default, we will use the lightweight native driver but
| you may specify any of the other wonderful drivers provided here.
|
| Supported: "file", "cookie", "database", "apc",
| "memcached", "redis", "array"
|
*/
'driver' => env('SESSION_DRIVER', 'file'),
/*
|--------------------------------------------------------------------------
| Session Lifetime
|--------------------------------------------------------------------------
|
| Here you may specify the number of minutes that you wish the session
| to be allowed to remain idle before it expires. If you want them
| to immediately expire on the browser closing, set that option.
|
*/
'lifetime' => 45,
'expire_on_close' => true,
/*
|--------------------------------------------------------------------------
| Session Encryption
|--------------------------------------------------------------------------
|
| This option allows you to easily specify that all of your session data
| should be encrypted before it is stored. All encryption will be run
| automatically by Laravel and you can use the Session like normal.
|
*/
'encrypt' => false,
/*
|--------------------------------------------------------------------------
| Session File Location
|--------------------------------------------------------------------------
|
| When using the native session driver, we need a location where session
| files may be stored. A default has been set for you but a different
| location may be specified. This is only needed for file sessions.
|
*/
'files' => storage_path('framework/sessions'),
/*
|--------------------------------------------------------------------------
| Session Database Connection
|--------------------------------------------------------------------------
|
| When using the "database" or "redis" session drivers, you may specify a
| connection that should be used to manage these sessions. This should
| correspond to a connection in your database configuration options.
|
*/
'connection' => null,
/*
|--------------------------------------------------------------------------
| Session Database Table
|--------------------------------------------------------------------------
|
| When using the "database" session driver, you may specify the table we
| should use to manage the sessions. Of course, a sensible default is
| provided for you; however, you are free to change this as needed.
|
*/
'table' => 'sessions',
/*
|--------------------------------------------------------------------------
| Session Sweeping Lottery
|--------------------------------------------------------------------------
|
| Some session drivers must manually sweep their storage location to get
| rid of old sessions from storage. Here are the chances that it will
| happen on a given request. By default, the odds are 2 out of 100.
|
*/
'lottery' => [2, 100],
/*
|--------------------------------------------------------------------------
| Session Cookie Name
|--------------------------------------------------------------------------
|
| Here you may change the name of the cookie used to identify a session
| instance by ID. The name specified here will get used every time a
| new session cookie is created by the framework for every driver.
|
*/
'cookie' => 'geeksquad_form_session',
/*
|--------------------------------------------------------------------------
| Session Cookie Path
|--------------------------------------------------------------------------
|
| The session cookie path determines the path for which the cookie will
| be regarded as available. Typically, this will be the root path of
| your application but you are free to change this when necessary.
|
*/
'path' => '/',
/*
|--------------------------------------------------------------------------
| Session Cookie Domain
|--------------------------------------------------------------------------
|
| Here you may change the domain of the cookie used to identify a session
| in your application. This will determine which domains the cookie is
| available to in your application. A sensible default has been set.
|
*/
'domain' => '.'.config('app.domain'),
/*
|--------------------------------------------------------------------------
| HTTPS Only Cookies
|--------------------------------------------------------------------------
|
| By setting this option to true, session cookies will only be sent back
| to the server if the browser has a HTTPS connection. This will keep
| the cookie from being sent to you if it can not be done securely.
|
*/
'secure' => false,
];
如果需要工厂的所有产品：
class Factory(Base):
__tablename__ = 'factorys'
ID = Column(Integer, primary_key=True)
products = relationship("Product",lazy='dynamic' )
class Product(Base):
__tablename__ = 'products'
ID = Column(Integer, primary_key=True)
factory_id = Column(Integer, ForeignKey('factorys.ID'))
Name = Column(Text)
应该适用。但是由于工厂已经在这个时间点装载，因此在工厂和产品之间进行加速的加载会更加高效。 但是，由于产品的大量收集，两个表之间的联合关系使得整体性能变差，并且例如在将产品附加到工厂时不需要。 是否可以在两个表之间定义不同的关系，但仅在特定情况下使用它们？例如，在工厂类的方法中，例如：
factory.products.all()
如何以高效的方式获得工厂的所有产品，而不是在向工厂添加产品时失去性能？ 任何提示将不胜感激。
答案 0 :(得分：1)
我遇到了同样的问题，很难找到答案。
你提出的返回关系的建议不会起作用，因为SQLAlchemy必须知道属于该表的关系，但是这样做：
class Factory(Base):
__tablename__ = 'factorys'
ID = Column(Integer, primary_key=True)
products_dyn = relationship("Product",lazy='dynamic', viewonly=True)
products = relationship("Product",lazy='joined' )
应该有效。注意viewonly属性，它非常重要，因为没有它，SQLAlchemy可能会在您将产品添加到工厂时尝试使用这两种关系，并且在特定情况下可能会产生重复的条目（例如使用关系的辅助表）。
通过这种方式，您既可以使用热切的产品，也可以使用连接执行优化查询，同时使用表声明隐藏它。
希望有所帮助！