fix: add support for default field values in editor components (#1616)

packages/netlify-cms-widget-markdown/src/MarkdownControl/VisualEditor.js

@@ -3,7 +3,7 @@ import PropTypes from 'prop-types';
 import ImmutablePropTypes from 'react-immutable-proptypes';
 import styled, { cx } from 'react-emotion';
 import { get, isEmpty, debounce } from 'lodash';
-import { Map } from 'immutable';
+import { List } from 'immutable';
 import { Value, Document, Block, Text } from 'slate';
 import { Editor as Slate } from 'slate-react';
 import { slateToMarkdown, markdownToSlate, htmlToSlate } from '../serializers';
@@ -142,15 +142,24 @@ export default class Editor extends React.Component {
   };
 
   handlePluginAdd = pluginId => {
+    const { getEditorComponents } = this.props;
     const { value } = this.state;
     const nodes = [Text.create('')];
+    const pluginFields = getEditorComponents()
+      .get(pluginId)
+      .get('fields', List());
+    const shortcodeData = pluginFields
+      .map(field => field.get('default'))
+      .filter(val => val)
+      .toMap()
+      .mapKeys((idx, field) => field.get('name'));
     const block = {
       object: 'block',
       type: 'shortcode',
       data: {
         shortcode: pluginId,
         shortcodeNew: true,
-        shortcodeData: Map(),
+        shortcodeData,
       },
       isVoid: true,
       nodes,