Identity Map and Request Context
MikroORM
uses identity map in background so you will always get the same instance of
one entity.
If you want to clear this identity map cache, you can do so via EntityManager.clear()
method:
You should always keep unique identity map per each request. This basically means that you need to clone entity manager and use the clone in request context. There are two ways to achieve this:
#
Forking Entity ManagerWith fork()
method you can simply get clean entity manager with its own context and identity map:
RequestContext helper for DI containers#
If you use dependency injection container like inversify
or the one in nestjs
framework, it
can be hard to achieve this, because you usually want to access your repositories via DI container,
but it will always provide you with the same instance, rather than new one for each request.
To solve this, you can use RequestContext
helper, that will use node
's Domain API in the
background to isolate the request context. MikroORM will always use request specific (forked)
entity manager if available, so all you need to do is to create new request context preferably
in middle:
You should register this middleware as the last one just before request handlers and before
any of your custom middleware that is using the ORM. There might be issues when you register
it before request processing middleware like queryParser
or bodyParser
, so definitely
register the context after them.