This is a plug and play component which uses HTML as I/O and saves it using Formik's setFieldValue()

HTML-based-DraftJS-Plugin-Component-For-Formik.js

import React, { Component } from "react";
import { convertToRaw, convertFromRaw } from "draft-js";
import { convertFromHTML, convertToHTML } from "draft-convert";
import {
	DraftailEditor,
	BLOCK_TYPE,
	INLINE_STYLE,
	ENTITY_TYPE
} from "draftail";
import "draft-js/dist/Draft.css";
import "draftail/dist/draftail.css";

class HTMLEditorComponent extends Component {
	exporterConfig = {
		blockToHTML: block => {
			if (block.type === BLOCK_TYPE.BLOCKQUOTE) {
				return <blockquote />;
			}

			// Discard atomic blocks, as they get converted based on their entity.
			if (block.type === BLOCK_TYPE.ATOMIC) {
				return {
					start: "",
					end: ""
				};
			}

			return null;
		},

		entityToHTML: (entity, originalText) => {
			if (entity.type === ENTITY_TYPE.LINK) {
				return <a href={entity.data.url}>{originalText}</a>;
			}

			if (entity.type === ENTITY_TYPE.IMAGE) {
				return <img src={entity.data.src} alt={entity.data.alt} />;
			}

			if (entity.type === ENTITY_TYPE.HORIZONTAL_RULE) {
				return <hr />;
			}

			return originalText;
		}
	};

	importerConfig = {
		htmlToEntity: (nodeName, node, createEntity) => {
			// a tags will become LINK entities, marked as mutable, with only the URL as data.
			if (nodeName === "a") {
				return createEntity(ENTITY_TYPE.LINK, "MUTABLE", {
					url: node.href
				});
			}

			if (nodeName === "img") {
				return createEntity(ENTITY_TYPE.IMAGE, "IMMUTABLE", {
					src: node.src
				});
			}

			if (nodeName === "hr") {
				return createEntity(
					ENTITY_TYPE.HORIZONTAL_RULE,
					"IMMUTABLE",
					{}
				);
			}

			return null;
		},
		htmlToBlock: nodeName => {
			if (nodeName === "hr" || nodeName === "img") {
				// "atomic" blocks is how Draft.js structures block-level entities.
				return "atomic";
			}

			return null;
		}
	};

	fromHTML = html => convertToRaw(convertFromHTML(this.importerConfig)(html));
	toHTML = raw =>
		raw ? convertToHTML(this.exporterConfig)(convertFromRaw(raw)) : "";

	onSave = content => {
		this.props.handleSave(this.props.fieldName, this.toHTML(content));
	};

	render() {
		return (
			<DraftailEditor
				rawContentState={this.fromHTML(this.props.contentValue) || null}
				onSave={this.onSave}
				blockTypes={[
					{ type: BLOCK_TYPE.ORDERED_LIST_ITEM },
					{ type: BLOCK_TYPE.UNORDERED_LIST_ITEM }
				]}
				inlineStyles={[
					{ type: INLINE_STYLE.BOLD },
					{ type: INLINE_STYLE.ITALIC },
					{ type: INLINE_STYLE.UNDERLINE }
				]}
				// entityTypes={[{ type: ENTITY_TYPE.HORIZONTAL_RULE }]}
			/>
		);
	}
}

export default HTMLEditorComponent;