form validation

controllers.application.js

import Ember from 'ember';

export default Ember.Controller.extend({
  appName: 'Ember Twiddle',
  firstName: ''
});

first-name.component.js

import Ember from 'ember';
import DS from 'ember-data';

const { Errors } = DS;
const { computed, isEmpty } = Ember;

const _checkValidation = (errors, value, labelText) => {
  let label = labelText.camelize();

  errors.remove(label);

  if(isEmpty(value)) {
    errors.add(label, 'Please enter is invalid');
  } else if (value.match(/(\d)+/g) && errors) {
    errors.add(label, 'String only please');
    return value;
  } else if (errors) {
    return value;
  }

}

export default Ember.Component.extend({
  errors: Errors.create(),
  label: 'Label text',
	needsValidation: true,
 
  value: computed('errors', {
    get() { return null; },
    set(_,v) {
      if (this.get('needsValidation') && this.get('startValidating')) {
        let { label, errors } = this.getProperties('errors', 'label');
        return _checkValidation(errors, v, label);
      }
    }
  }),
  
  actions: {
    startValidating() {
      this.set('startValidating', true);
    }
  }
});

first-name.template.hbs

<label>First Name</label>
<br />

{{input value=(mut value) focus-in=(action 'startValidating')}}
<span>{{errors.firstObject.message}}</span>

input-surname.component.js

import Ember from 'ember';

const { computed } = Ember;

export default Ember.Component.extend({
  value: null,
  errors: computed('value', function() {
  	let value = this.get('value');
    console.log(1);
    return [
      {message: 'Please enter the string'}
    ]
  })
});

input-surname.template.hbs

{{yield}}
<label>Surname</label>
<br/>
{{input value=value}}

{{#each errors as |error|}}
	{{log error}}
  <span>{{error.message}}</span>
{{/each}}

router.js

import Ember from 'ember';
import config from './config/environment';

const Router = Ember.Router.extend({
  location: 'none',
  rootURL: config.rootURL
});

Router.map(function() {
});

export default Router;

templates.application.hbs

<h1>Welcome to {{appName}}</h1>
<br>
<br>
hello {{firstName}}
{{first-name value=firstName}}
<br />
{{input-surname errors=errors}}
{{outlet}}
<br>
<br>

twiddle.json

{
  "version": "0.10.4",
  "EmberENV": {
    "FEATURES": {}
  },
  "options": {
    "use_pods": true,
    "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": {}
}