New Twiddle

controllers.application.js

import Ember from 'ember';

export default Ember.Controller.extend({
  appName: 'Ember Twiddle',
  _membersMaleCount: 1,
  membersCount: 5,
  membersMaleCount: Ember.computed('_membersMaleCount', {
    get() {
      return this.get('_membersMaleCount')
    },
    set(key, value) {
      let total = this.get('membersCount')

      if(value < 0) {
        value = 0
      } else if(value > total) {
        value = total
      }

      this.set('_membersMaleCount', value)

      return value
    }
  }),
});

routes.application.js

import Ember from 'ember';

export default Ember.Route.extend({
  model() {
    return {
      membersCount: 5,
      membersMaleCount: 1
    };
  }
});

templates.application.hbs

<h1>Welcome to {{appName}}</h1>
<br>
<br>
{{outlet}}
{{input type="number" max=model.membersCount                                                             
          min="0" step="1"
          value=membersMaleCount        
          class="form-control form_gender"}}
          
{{membersMaleCount}}

{{appName}}
<br>
<br>

twiddle.json

{
  "version": "0.10.2",
  "EmberENV": {
    "FEATURES": {}
  },
  "options": {
    "use_pods": false,
    "enable-testing": false
  },
  "dependencies": {
    "jquery": "https://cdnjs.cloudflare.com/ajax/libs/jquery/1.11.3/jquery.js",
    "ember": "2.7.0",
    "ember-data": "2.7.0",
    "ember-template-compiler": "2.7.0"
  },
  "addons": {}
}