customimagefieldtype.js

const Fieldtype = {
  mixins: [window.Storyblok.plugin],
  template: `
    <div>
      <div class="uk-grid">
        <div class="uk-width-1-5" v-if="has_image">
          <img :src="model.src"/>
        </div>
        <div :class="{ 'uk-width-4-5': has_image, 'uk-width-1-1': !has_image }" >
         <input class="uk-width-1-1" placeholder="Your image URL" v-model="model.src" />
        </div>
      </div>
    <sb-asset-selector :uid="uid" field="src"></sb-asset-selector>
  </div>`,
  computed: {
    has_image() {
      return this.model.src !== ''
    }
  },
  methods: {
    initWith() {
      return {
        plugin: 'imagefieldtest',
        src: ''
      }
    },
    pluginCreated() {
      console.log('plugin:created')
    }
  },
  watch: {
    'model': {
      handler: function (value) {
        this.$emit('changed-model', value);
      },
      deep: true
    }
  }
}