title: Vee validate across multiple fields
body: <p>How can i validate a list of values across fields where at least one single value has to be set (not zero) </p>
  
  <p>I need to validate that at least one field is entered (eg the total is not zero)</p>
  
  <p>The issue I have is that the validator::total_cost does not re-evaluate all the fields under validation when any one of them changes.</p>
  
  <p><em>Typing a correct value in "any" input needs to tell "all" the other inputs to revaluate against the new computed field !</em></p>
  
  <p>Any help would be grateful.</p>
  
  <p>eg (my set is much much larger)</p>
  
  <pre><code> V1  V2  V3  V4  V5          Tot
  [0] [0] [0] [0] [0] -------- [0] (invalid)  
  [0] [0] [0] [0] [1] -------- [1] (valid)
  [1] [0] [0] [0] [1] -------- [2] (valid)
  [0] [0] [1] [0] [1] -------- [3] (valid)
  </code></pre>
  
  <p>The markup i am using </p>
  
  <pre><code>&lt;input type="text" v-model.number="v1" data-vv-as="v1" v-validate="anyValue":name="v1"/&gt;
  
  &lt;input type="text" v-model.number="v1" data-vv-as="v2" v-validate="anyValue":name="v2"/&gt;
  
  &lt;input type="text" v-model.number="v2" data-vv-as="v3" v-validate="anyValue":name="v3"/&gt;
  
  &lt;input type="text" v-model.number="v3" data-vv-as="v4" v-validate="anyValue":name="v4"/&gt;
  
  &lt;input type="text" v-model.number="v4" data-vv-as="v5" v-validate="anyValue":name="v5"/&gt;
  </code></pre>
  
  <p>AnyValue is a computed property</p>
  
  <pre><code> computed: {
      anyValue: function () {
          return {
             // required: true,
              between: [0, 99999999],
              decimal: 2,
              total_cost: this.totalCost /* THIS IS COMPUTED */
          }
      },
      totalCost: function () {
          return this.v1 + this.v2 + this.v3 + this.v4 + this.v5;           
      }
   created: function () {
      this.$validator.extend('total_cost', {
          vTotalCost:0,
          getMessage: function (field) { 
           return 'At least one value must be supplied'; 
          },
          validate: function (value) {
              this.vTotalCost = value;
              console.log("the value is " + this.vTotalCost);
              return this.vTotalCost != 0;                
          }
      });
  },
  </code></pre>