Can't call a function inside a function in Typescript

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

Can you paste the rest of the code from that file? – Ion Jul 14 '19 at 15:04 — Ion, Jul 14 '19 at 15:04
The whole class is here: https://pastebin.com/b8a2E3EZ – bojackhorseman99 Jul 14 '19 at 15:25 — bojackhorseman99, Jul 14 '19 at 15:25

score 2 · Answer 1 · answered Jul 14 '19 at 15:16

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

score 1 · Accepted Answer · answered Jul 14 '19 at 15:09

1

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.

answered Jul 14 '19 at 15:09

Ion

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This is the class that calls subirArchivo: https://pastebin.com/pKnNUW3U – bojackhorseman99 Jul 14 '19 at 15:28
1

add a uploadController.subirArchivo.bind(uploadController) – Ion Jul 14 '19 at 15:29

Can't call a function inside a function in Typescript

2 Answers2