title: Vee-Validate custom date validation
body: <p>I was wondering if there is anyway you can write a custom date validation using vee-validate plugin where the end date cannot be less than the start date? I have looked high and low, and there is nowhere I can find a definite answer to this. </p>
  
  <p>If there is no way to implement this, then I can make do without it, however, right now what I have implemented in my template for my start date is:</p>
  
  <pre><code>&lt;input type="text" id="startDate" name="startDate" class="form-control" v-model="startDate" v-validate="'required|date_format:DD-MM-YYYY'" :class="{'input': true, 'is-danger': errors.has('startDate') }"&gt;
      &lt;label class="mb-0" for="startDate"&gt;Start Date&lt;/label&gt;
          &lt;span v-show="errors.has('startdate')" class="text-danger"&gt;&lt;center&gt;{{ errors.first('startdate') }}&lt;/center&gt;&lt;/span&gt;
  </code></pre>
  
  <p>My script looks like this:</p>
  
  <pre><code>    export default {
      name: 'App',
      data: () =&gt; ({
          task: '',
          startDate: '',
          startTime: '',
          endDate: '',
          endTime: '',
          description: 'test'
      }),
      methods: {
          validateBeforeSubmit() {
              this.$validator.validateAll().then((result) =&gt; {
                  if (result) {
                  // eslint-disable-next-line
                  alert('Form Submitted!');
                  return;
                  }
  
                  alert('Correct them errors!');
              });
          }
      }
  
  };
  </code></pre>
  
  <p>But there is no validation that is showing up. I think I am missing something in my script but I am not sure how to implement the date into there. Any help would be greatly appreciated.</p>