In a data table, I want to display only items, where the property 'display' is 'true'. There is the property 'filter' in the component [v-data-table](https://vuetifyjs.com/en/components/data-tables). But there is no example showing, how to use it.

I have tried several approaches, but without success. The following code snippet is also available at [codepen](https://codepen.io/antoninslejska/pen/qKwBda).

```js
new Vue({
  el: '#app',
  data () {
    return {
      headers: [
        {
          text: 'Dessert (100g serving)',
          align: 'left',
          sortable: false,
          value: 'name'
        },
        { text: 'Calories', value: 'calories' },
        { text: 'Fat (g)', value: 'fat' },
        { text: 'Carbs (g)', value: 'carbs' },
        { text: 'Protein (g)', value: 'protein' },
        { text: 'Iron (%)', value: 'iron' }
      ],
      desserts: [
        {
          value: false,
          name: 'Frozen Yogurt',
          calories: 159,
          fat: 6.0,
          carbs: 24,
          protein: 4.0,
          iron: '1%',
          display: false
        },
        {
          value: false,
          name: 'Ice cream sandwich',
          calories: 237,
          fat: 9.0,
          carbs: 37,
          protein: 4.3,
          iron: '1%',
          display: true
        },
        {
          value: false,
          name: 'Eclair',
          calories: 262,
          fat: 16.0,
          carbs: 23,
          protein: 6.0,
          iron: '7%',
          display: false
        },
        {
          value: false,
          name: 'Cupcake',
          calories: 305,
          fat: 3.7,
          carbs: 67,
          protein: 4.3,
          iron: '8%',
          display: true
        },
        {
          value: false,
          name: 'Gingerbread',
          calories: 356,
          fat: 16.0,
          carbs: 49,
          protein: 3.9,
          iron: '16%',
          display: false
        },
        {
          value: false,
          name: 'Jelly bean',
          calories: 375,
          fat: 0.0,
          carbs: 94,
          protein: 0.0,
          iron: '0%',
          display: true
        },
        {
          value: false,
          name: 'Lollipop',
          calories: 392,
          fat: 0.2,
          carbs: 98,
          protein: 0,
          iron: '2%',
          display: false
        },
        {
          value: false,
          name: 'Honeycomb',
          calories: 408,
          fat: 3.2,
          carbs: 87,
          protein: 6.5,
          iron: '45%',
          display: false
        },
        {
          value: false,
          name: 'Donut',
          calories: 452,
          fat: 25.0,
          carbs: 51,
          protein: 4.9,
          iron: '22%',
          display: false
        },
        {
          value: false,
          name: 'KitKat',
          calories: 518,
          fat: 26.0,
          carbs: 65,
          protein: 7,
          iron: '6%',
          display: false
        }
      ]
    }
  },
  methods: {
    filterItems(val, search) {
      return val.display;
    }
  }
})
```

```html
<!DOCTYPE html>
<html>
<head>
  <link href='https://fonts.googleapis.com/css?family=Roboto:300,400,500,700|Material+Icons' rel="stylesheet">
  <link href="https://unpkg.com/vuetify/dist/vuetify.min.css" rel="stylesheet">
  <meta name="viewport" content="width=device-width, initial-scale=1, maximum-scale=1, user-scalable=no, minimal-ui">
</head>
<body>

<div id="app">
  <v-app id="inspire">
    <v-data-table
      :headers="headers"
      :items="desserts"
      hide-actions
      item-key="name"
      :filter="filterItems"
    >
      <template slot="items" slot-scope="props">
        <tr @click="props.expanded = !props.expanded" :class="[props.expanded && 'expanded']">
          <td>{{ props.item.name }}</td>
          <td class="text-xs-right">{{ props.item.calories }}</td>
          <td class="text-xs-right">{{ props.item.fat }}</td>
          <td class="text-xs-right">{{ props.item.carbs }}</td>
          <td class="text-xs-right">{{ props.item.protein }}</td>
          <td class="text-xs-right">{{ props.item.iron }}</td>
        </tr>
      </template>
      <template slot="expand" slot-scope="props">
        <v-card flat>
          <v-card-text>Peek-a-boo!</v-card-text>
        </v-card>
      </template>
    </v-data-table>
  </v-app>
</div>

  <script src="https://unpkg.com/vue/dist/vue.js"></script>
  <script src="https://unpkg.com/vuetify/dist/vuetify.js"></script>
</body>
</html>
```

The problematic part of the code is:

```
  methods: {
    filterItems(val, search) {
      return ???;
    }
  }

```