在构造函数中创建具有属性的类时出错

Question

I have created this class:

export class ModelTransformer {
  constructor(private readonly hostelTransformer: HostelTransformer) {}

  static transform(hostel: Hostel): Hotel {
    return hostelTransformer.transform(hostel);
  }
}

But when I compile it I have this compilation error:

error TS2304: Cannot find name 'hostelTransformer'.

I also tried

 static transform(hostel: Hostel): Hotel {
        return this.hostelTransformer.transform(hostel);
      }

but then I have the error:

error TS2339: Property 'hostelTransformer' does not exist on type 'typeof ModelTransformer'.

Answer 1

You can't access the instance properties inside static methods.

When you use private readonly hostelTransformer: HostelTransformer in the constructor, it goes on the instance of the ModelTransformer class. Like this

constructor(hostelTransformer) {
  this.hostelTransformer = hostelTransformer;
}

You can't use return this.hostelTransformer.transform(hostel) because transform is a static method. When you call ModelTransformer.transform() , this will be ModelTransformer and not the instance of the class.

If you want to use that property, you need to make the method non-static