feat(core): allow setting default schema on EntityManager

[EmmEm]

Hi,

I want to start with thanking you all for this great ORM that is so actively maintained and offer so many great features. One thing that really catches my eye is the per request (shell)EntityManager that I think will make this ORM a winner when it comes to multi tenancy. Almost all of the other big ORM libraries are based on a global concept.

My aim with this PR is to make a shoot at implementing schema based multi tenancy support with help of the per request EntityManager. With this PR it's possible to set a schema when forking the EntityManager. That schema will be applied as a default schema if no other schema is present. It makes use of the schema options introduced in: #2296

If this seems like an approach to pursue there is some more work to do:

• Add a hook in the other packages like Nestjs to allow for setting schema / request
• Documentation
• More extensive tests

Some questions

• Should the number of this.context() calls be reduced?
• When .fork() an existing fork with schema, should schema be inherited and should it be possible to clear schema?

[B4nan]

i like the idea, but the implementation can simplified

[codecov]

Codecov Report

Patch coverage is 100.00% of modified lines.

❗ Current head 960fcbc differs from pull request most recent head 828f117. Consider uploading reports for the commit 828f117 to get more accurate results

Files Changed	Coverage
packages/core/src/EntityManager.ts	100.00%
packages/core/src/unit-of-work/UnitOfWork.ts	100.00%
packages/core/src/utils/RequestContext.ts	100.00%

📢 Thoughts on this report? Let us know!.

[B4nan]

So I guess the last missing thing is to document this somewhere? We should also come up with a better commit message as this is a bit too generic for what this PR is actually doing.

[EmmEm]

I've tested some more with request context and found an issue. I think we need to change this._schema for this.schema otherwise it wont work when using request context. this._schema will refer to the global EntityManager instance which will be wrong.

[B4nan]

I don't follow, change it where?

[B4nan]

Unless you plan to make more changes, we can merge.

[B4nan]

Thanks!