无法在Typescript中的函数内调用函数

Question

basically what i have is an Angular Web Page that uploads a file to the server through a POST which my NodeJS app receives.

My problem comes when i am trying to receive the file path through subirArchivo() and sending it through a function called InsertaPersonas(). I have tried several methods but it always results in the function being called undefined, it doesn't even enter the function once.

Here is my code:

     subirArchivo(req: Request, res: Response) {
    var form = new IncomingForm();
    let readStream;
    var self = this;
    this.insertaPersonas('a'); // function undefined

    form.parse(req);
    form.on('file', (field: any, file: any) => {
      // Do something with the file
      // e.g. save it to the database
      // you can access it using file.path
      console.log('file', file.name); //this works
      readStream = fs.createReadStream(file.path); // this works
      // console.log(file.path); //this works
      self.insertaPersonas(file.path); //function undefined
    });
    form.on('end', () => {
      res.json();
    });
  }

Here it is my whole class: https://pastebin.com/b8a2E3EZ

Answer 1

It looks like a typical bind issue;

class MyClass {
  other () {
    console.log('enter')
  }
  fn () {
    this.other()
  }
}

const instance = Class()
instance.fn() // works

Promise.resolve()
  .then(instance.fn.bind(instance)) // works

Promise.resolve()
  .then(instance.fn) // fails: this.other is undefined, not a function

You could try finding from where you call your subirArchivo function, and make sure it is called like myInstance.subirArchivo() , or bind the instance first, either where you reference it myInstance.subirArchivo.bind(myInstance) , or in the constructor:

class UploadController {

  constructor () {
    this.subirArchivo = this.subirArchivo.bind(this)
  }

  insertaPersonas (...) { ... }
  subirArchivo () { ... this.insertaPersonas(...) ... }

}

For more, see Use of the JavaScript 'bind' method

Answer 2

Your problem is probably the self reference. That self=this is also unneeded because of the arrow function.

Who is calling subirArchivo ?

I would guess that self in that scope is not your uploadController class.