Improve param decorators

[andrew-yustyk]

This PR fixes 2 bugs in ConfigParam() and Configurable() decorator

1. ConfigParam() decorator set metadata to the target: Reflect.defineMetadata(CONFIG_PARAMS, existingParameters, target), but always retrieved it from target's property: Reflect.getMetadata(CONFIG_PARAMS, target, propertyKey). So previous metadata was deleted if decorator was called 2 times or more on the same method.

2. Utility applyParamsMetadataDecorator() set config param to the argument only if the argument exists and it's an object (some unsafe condition as for me). So ConfigParam() decorator worked only the ConfigService() was injected on the argument's place.

But it's a fact that ConfigService may be not injected in all required places (check additional tests).
So I also added improvements to the applyParamsMetadataDecorator() utility.

P.S. Probably it is't a question to the nestjs-config and not a topic of this PR, but when Configurable() decorator applied to the controller method and it was placed to top of order - it breaks other decorators.

  @Configurable()
  @Get('cats')
  @UseInterceptors(MyInterceptor)
  public getMostLikedPosts(@ConfigParam('key') key):  {
    return [];
  }

I think it's because it replaces original method with own function.
It will be nice to have some note in the Readme that Configurable() decorator must be the last.

[coveralls]

Pull Request Test Coverage Report for Build 97

• 11 of 11 (100.0%) changed or added relevant lines in 2 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage increased (+3.04%) to 95.135%

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Totals
Change from base Build 84:	3.04%
Covered Lines:	133
Relevant Lines:	133

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💛 - Coveralls

[bashleigh]

Could you add a note to the readme about the @Configurable decorator underneath the decorator code example please :) https://github.com/nestjs-community/nestjs-config#decorators
Is this only happening in your PR though? If not we'll investigate!

Other than that it looks pretty cool! Thanks :)

[andrew-yustyk]

Readme is updated with the description and examples.
Also I've created an issue on nextjs repository for this behavior - nestjs/nest#1180

[andrew-yustyk]

Is this only happening in your PR though?

No, this is behavior of the current nestjs-config version (1.2.4) and also it reproduces in the PR.
Unfortunately I could not fix it

[shekohex]

Thank you 😃

Another side note, can you just add a good tip in the ReadMe file that as a good practice, one should make the injected @ConfigParam(...) parameter in the method to be optional.
So that if he is trying to call it manually, not have to add a null or make it's type of any.

Thank you again 😃.

[shekohex]

As a side note, to get rid of null, null
You could make the parameters optional ?
So you don't have to to pass it to the method.

[shekohex]

Nice, bravoo 👏

[andrew-yustyk]

PR updated.

@shekohex , I've updates parameter types in the tests and Readme as you asked.
Also I've added more strict checking and some comments to applyParamsMetadataDecorator util.
Additional test were added.

[shekohex]

Well done 😃