add count (.length) each items in option on v-select

I want add count course.length from api each item option on v-select and show data to active based filter
For example, items in v-select: all(count), passed(count) : filter from online.passed, not complete(count) filter from online.complete, etc.

template in vue.js

<template>
  <v-select
    v-model="filter"
    :items="items"
  ></v-select>
  <v-card v-for="online in onlineCourse" :key="online.id">
    <v-card-title>{{online.title}</v-card-title>
    <p v-if="online.complete === 100">{{online.complete}}%</p>
    <p v-else-if="online.complete < 100 && online.complete > 0">{{online.complete}}%</p>
    <p v-else>{{online.complete}}%</p>
  </v-card>
</template>
<script>
  data () {
   return {
     onlineCourse: [],
     filter: 'All',
     items: [
      'All',
      'passed',
      'not complete',
     ],
   }
 }
 method: {
   async getDataOnline () {
    try {
      const request = await Axios.get('v1/courses')
      this.onlineCourse = request.courses
    } catch (error) {
      console.log(error.message);
    }
   }
 }
</script>

.json

 "courses": [
    {
        "id": 1,
        "title": "title1",
        "passed": false,
        "completed": 0
    },
    {
        "id": 2,
        "title": "title2",
        "passed": true,
        "completed": 100
    },
    {
        "id": 3,
        "title": "title3",
        "passed": false,
        "completed": 50
    }
],