Deprecate Application Controller Router Properties

Summary

This RFC proposes the deprecation of ApplicationController#currentPath and ApplicationController#currentRouteName.

Motivation

These APIs are no longer needed as the RouterService now has RouterService#currentPath and RouterService#currentRouteName. These fields are only ever present on the application controller which is a weird special casing that we would like to remove. Additionally, it's likely that there are very few if any consumers of this API as it is not documented.

Transition Path

If you are reliant on ApplicationController#currentPath and ApplicationController#currentRouteName you can get the same functionality from the RouterService to migrate, inject the RouterService and read the currentRouteName or currentPath off of it.

Before:

// app/controllers/application.js
import Controller from '@ember/controller';
import fetch from 'fetch';

export default Controller.extend({
  store: service('store'),

  actions: {
    sendPayload() {
      fetch('/endpoint', {
        method: 'POST',
        body: JSON.stringify({
          route: this.currentRouteName
        })
      });
    }
  }
})

After:

// app/controllers/application.js
import Controller from '@ember/controller';
import fetch from 'fetch';

export default Controller.extend({
  store: service('store'),
  router: service('router'),

  actions: {
    sendPayload() {
      fetch('/endpoint', {
        method: 'POST',
        body: JSON.stringify({
          route: this.router.currentRouteName
        })
      });
    }
  }
})

How We Teach This

There is likely very few consumers of this functionality and migration path is covered by existing documentation.

Drawbacks

This may introduce churn that we are not aware of.

Alternatives

No real alternative other than keep setting the properties.

Unresolved questions

Optional, but suggested for first drafts. What parts of the design are still TBD?