Typescript inheritance

Question

I have some questions about typescript/javascript inheritance. I have the following base class (express controller router):

abstract class BaseCtrl {
  abstract model;

  // Get all
  getAll = (req, res) => {
    this.model.find({}, (err, docs) => {
      if (err) { return console.error(err); }
      res.json(docs);
    });
  };
export default BaseCtrl;

And the following class that implements that base:

import BaseCtrl from './base';
import Card from '../models/card';

export default class CardCtrl extends BaseCtrl {
  model = Card;

  getAll = (req, res) => {
    super.getAll(req, res);
  }

}

This code gives me the error:

Only public and protected methods of the base class are accessible via the super keyword

I would like to know how to call the super method. Can anyone help me?

Matias Cicero · Accepted Answer · 2017-06-30 18:43:53Z

2

You need to define getAll as a proper method:

abstract class BaseCtrl {
    abstract model;

    // Get all
    getAll(req, res) {
        this.model.find({}, (err, docs) => {
            if (err) { return console.error(err); }
            res.json(docs);
        });
    }
};
export default BaseCtrl;

Then, you can override it:

import BaseCtrl from './base';
import Card from '../models/card';

export default class CardCtrl extends BaseCtrl {
     model = Card;

     getAll(req, res) {
       super.getAll(req, res);
     }
}

answered Jun 30, 2017 at 18:43

Matias Cicero

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1 Comment

Guilherme Chiara Over a year ago

Hi Matias! Thanks for you answer! Do you know how can I get this code working with the routes.route: router.route('/cards').get(passport.authenticate('login', {session: false}), cardCtrl.getAll); If I transform like you said, this code gets broken, because getAll is not more a property with function.

Mouneer · Accepted Answer · 2017-07-01 02:17:20Z

0

Working DEMO

You're defining getAll as a member property but you need to define it as a normal member method

Typescript overriding features works properly with member methods and not properties.

abstract class BaseCtrl {
    abstract model;    
    // Get all
    getAll (req, res) {
        this.model.find({}, (err, docs) => {
            if (err) { return console.error(err); }
            res.json(docs);
        });
    };
}

export class CardCtrl extends BaseCtrl {   
  getAll (req, res) {
    super.getAll(req, res);
  }

}

Propably, you may need to use getAll as a reference when passing to the router,So you may need to bind the scope like this cardCtrl.getAll.bind(cardCtrl);

edited Jul 1, 2017 at 2:17

answered Jun 30, 2017 at 18:44

Mouneer

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3 Comments

Guilherme Chiara Over a year ago

Hi Mouneer. Have you ever faced the problem that "this" is undefined in the base class, using this code? I'm getting this error and I don't know why!

Mouneer Over a year ago

check my edit. Instead of using it as cardCtrl.getAll bind the scope. Got it?

Guilherme Chiara Over a year ago

Great! Thank you so much Mouneer! :)

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