daw/js/guten.js

registerBlockType('my-plugin/event-location', {
  title: 'Media URL',
  category: 'widgets',

  attributes: {
    location: {
      type: 'string',
      source: 'meta',
      meta: 'media_url'
    }
  },

  edit ({ className, attributes, setAttributes }) {
    const { location } = attributes

    function updateContent (e) {
      setAttributes({ location: e.target.value })
    }

    return el(
      'p',
      { className: className },
      el(
        'input',
        { value: location, onChange: updateContent }
      )
    )
  },

  save () {
    return null
  }
})