limiting properties

application.controller.js

import Ember from 'ember';

export default Ember.Controller.extend({
  appName: 'Ember Twiddle',
  queryParams: {
    'number': '_number'
  },
  _number: 1,
  totalPages: 5,
  number: Ember.computed('_number', {
    get(key) {
      return this.get('_number');
    },
    set(key, value) {
      console.log('Setting', key, value);
      const totalPages = this.get('totalPages');
      
      if(value > totalPages) {
        return totalPages;
      }
      
      if(!value || this.get('_number') < 1) {
        return 1;
      }
      
      return value;
    }
  }),
  actions: {
    increment() {
      this.incrementProperty('number');
    },
    decrement() {
      this.decrementProperty('number');
    }
  }
});

application.template.hbs

<h1>Welcome to {{appName}}</h1>
<br>
<br>
{{outlet}}
{{#my-component number=number totalPages=totalPages}}{{/my-component}}

<button {{action "increment"}}>Increment</button>
<button {{action "decrement"}}>Decrement</button>
<br>
<br>

my-component.component.js

import Ember from 'ember';

export default Ember.Component.extend({
  totalPages: 0,
  number: 0
});

my-component.template.hbs

<p>Total Pages: {{totalPages}}</p>
<p>The number is: {{number}}</p>

twiddle.json

{
  "version": "0.6.5",
  "EmberENV": {
    "FEATURES": {}
  },
  "options": {
    "enable-testing": false
  },
  "dependencies": {
    "jquery": "https://cdnjs.cloudflare.com/ajax/libs/jquery/1.11.3/jquery.js",
    "ember": "https://cdnjs.cloudflare.com/ajax/libs/ember.js/2.4.3/ember.debug.js",
    "ember-data": "https://cdnjs.cloudflare.com/ajax/libs/ember-data.js/2.4.0/ember-data.js",
    "ember-template-compiler": "https://cdnjs.cloudflare.com/ajax/libs/ember.js/2.4.3/ember-template-compiler.js"
  }
}