Fix for @Param() decorator

[gregmagolan]

I was trying out the @param() decorator with the latest code @nestjs/core@4.1.3 and found it wasn't working. Its not mentioned in your documentation at https://docs.nestjs.com/components but there is a reference to it in cats.controller.ts in the 01-cats-app example:

  @Get(':id')
  findOne(@Param('id', new ParseIntPipe()) id) {
    // logic
  }

In any case, I tracked the issue down to code in router-execution-context.ts and router-explorer.ts where callback.name was not defined for the follow two ReflectMetadata calls:

return Reflect.getMetadata(ROUTE_ARGS_METADATA, instance, callback.name);

and

return Reflect.getMetadata(PARAMTYPES_METADATA, instance, callback.name);.

This PR fixes it by passing the methodName from router-explorer.ts to the create function in router-execution-context.ts and down to these two calls which now look like:

return Reflect.getMetadata(ROUTE_ARGS_METADATA, instance, methodName);

and

return Reflect.getMetadata(PARAMTYPES_METADATA, instance, methodName);

This fixes the issue and my code which looks like the following now gets the :id parameter string from the route:

@Controller('foo')
export class FooController {
  @Get('get/:id')
  get(@Param('id') id: string): any {
    console.log(id);
    return null;
  }
}

[gregmagolan]

In short, when my code is transpiled down to .js, the typescript function

get(@Param('id') id: string): any {
    console.log(id);
    return null;
  }

ends up a nameless function (function() {...}) so callback.name doesn't work in this case.

[coveralls]

Coverage remained the same at 93.951% when pulling aae4dc3 on gregmagolan:bugfix/fix-for-param-decorator into dc7869b on nestjs:master.

[gregmagolan]

@kamilmysliwiec Any chance this can make it into the next version of @nestjs/core? Right now I'm using a custom dist for my project.

#221 reproduces the issue this PR fixes. Its happens when transpiling down to es5 (as I do in my project and I'm building with Bazel and it targets es5 by default and can't be changed easily). In anycase, it's good to have nest work with both ES6 and ES6.

[kamilmysliwiec]

Hi @gregmagolan,
Fantastic job, thanks! However, transpiling down to es5 may cause any other unexpected issues. For example, the class-based middlewares might not work correctly. I have already pulled your repo and tested your changes, so they'll available in the incoming update, but still, you should consider (if it's possible!) to move to es6.

[lock]

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