title: Is it possible to validate single route parameter?
body: <p>Let's say I have following route:</p>
  
  <pre><code>companies/{companyId}/departments/{departmentId}/employees
  </code></pre>
  
  <p>Is it possible to validate both resources ids (<code>companyId</code>, <code>departmentId</code>) separately? I've tried following but it's not working.</p>
  
  <pre><code>class ResourceId {
    @IsNumberString()
    @StringNumberRange(...) // my custom validator
    id: number;
  }
  
  @Get(':companyId/departments/:departmentId/employees')
  getEmployees(
    @Param('companyId') companyId: ResourceId,
    @Param('departmentId') departmentId: ResourceId,
  ) {}
  </code></pre>
  
  <p>I have multiple cases when there is more than one parameter in the single route. I would not like to create separate validation class for every route. Is there a way to handle this problem in a different way?</p>