feat(): support typeorm ^0.3.0 version

[kamilmysliwiec]

PR Checklist

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• The commit message follows our guidelines: https://github.com/nestjs/nest/blob/master/CONTRIBUTING.md
• Tests for the changes have been added (for bug fixes / features)
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PR Type

What kind of change does this PR introduce?

• Bugfix
• Feature
• Code style update (formatting, local variables)
• Refactoring (no functional changes, no api changes)
• Build related changes
• CI related changes
• Other... Please describe: Upgrade

What is the current behavior?

Issue Number: N/A

What is the new behavior?

Does this PR introduce a breaking change?

• Yes
• No

Other information

[lovetodream]

Looks great!

[zbarbuto]

Not sure what the current requirement for Nest is but worth noting that TypeORM 0.3.x also drops support for node < 14:

compilation target now is es2020. This requires Node.JS version 14+

[dsbert]

Will this change be considered a breaking change for nestjs? If so, does that mean it will be deferred until version 9? There are some features we are hoping to utilize from the latest TypeORM, so I'm just wondering what the potential timeline could be and if we need to look at alternative solutions in the interim.

[kamilmysliwiec]

@dsbert we won't wait till v9

[Rainson12]

this PR is extremely useful since it allows bigger applications to load related entities using multiple queries instead of doing everything in one query with plenty of leftjoins which leads to a cartesian explosion/very long loading times.

[kamilmysliwiec]

This has been published under the next tag (npm i @nestjs/typeorm@next)

[dsbert]

What is the new recommended way of creating and injecting custom repositories? I understand using the extend function now on a normal repository, but is there an example of how that should work with the DI system?

[DEG-CD]

any idea of arrival time to stable branch?

[anchan828]

@dsbert I don't know if this is the recommended approach, but at least for my application the transition was very smooth.

https://gist.github.com/anchan828/9e569f076e7bc18daf21c652f7c3d012