title: How to call method in setup of vuejs3 app?
body: <p>In vuejs3 app I retrieve data from db with axios in method, like :</p>
  <pre><code>&lt;script&gt;
    import appMixin from '@/appMixin'
    import app from './../../App.vue' // eslint-disable-line
    import axios from 'axios'
  
    const emitter = mitt()
  
    export default {
      name: 'adminCategoriesList',
      mixins: [appMixin],
      data: function () {
        return {
          categoriesPerPage: 20,
          currentPage: 1,
          categoriesTotalCount: 0,
          categories: []
        }
      },
  
      components: {
      },
      setup () {
        const adminCategoriesListInit = async () =&gt; {
          this.loadCategories() // ERROR HERE
        }
  
        function onSubmit (credentials) {
          alert(JSON.stringify(credentials, null, 2))
          console.log('this::')
          console.log(this)
          console.log('app::')
        }
  
        onMounted(adminCategoriesListInit)
  
        return {
          // schema,
          onSubmit
        }
      }, // setup
  
      methods: {
        loadCategories() {
          ...
        }
  </code></pre>
  <p>and I got error in browser's console :</p>
  <pre><code>Cannot read property 'loadCategories' of undefined
  </code></pre>
  <p>If to remove “this.” in loadCategories call
  I got error :</p>
  <pre><code>'loadCategories' is not defined
  </code></pre>
  <p>I need to make loadCategories as method, as I need to cal;l it from different places.</p>
  <p>Which way is correct ?</p>
  <p>Thanks!</p>