Isomorphically render html string with Koa - rendering

Question

I'm trying to get Koa to isomorphically render a html string it receives from react-router.
Here's the code I've been trying to make work:
server.js
import koa from 'koa';
import React from "react";
import Router from "react-router";
import routes from "./routes";
const server = koa();
const port = process.env.NODE_ENV || 8000;
server.use(function *() {
try {
yield Router.run(routes, this.request.url, function (Handler) {
var content = React.renderToString(<Handler/>)
this.body = content
})
}
catch (err) {
this.status = err.status || 500;
this.body = err.message;
this.app.emit('error', err, this);
}
})
server.listen(port, function(err) {
if (err) throw err;
console.log("Server running on: http://localhost:"+port)
})
routes.js
import React from "react"
import {Route, DefaultRoute} from "react-router"
import Main from "./components/main"
export default (
<Route path="/">
<DefaultRoute handler={Main} name="main" />
</Route>
)
main.js
import React from "react"
const Main = React.createFactory(React.createClass ({
render () {
return (
<div>HELLO</div>
)
}
}))
export default Main
Getting several errors:
Warning: Component(...): No render method found on the returned
component instance: you may have forgotten to define render in your
component or you may have accidentally tried to render an element
whose type is a function that isn't a React component.
Warning: Don't set the props property of the React element. Instead,
specify the correct value when initially creating the element.
TypeError: Can't add property context, object is not extensible
Warning: Something is calling a React component directly. Use a
factory or JSX instead. See: https://fb.me/react-legacyfactory

Answer 1

for those who needs an answer with this, hope this will help you guys.
server.js
import koa from 'koa';
import React from "react";
import Router from "react-router";
import routes from "./routes";
const server = koa();
let handler;
server.use(function *(next) {
Router.run(routes, this.request.url, (Handler) => {
handler = React.renderToString(<Handler/>);
});
yield next;
});
server.use(function *() {
this.body = handler;
});
export default server;
components/index.js
import React from "react";
const Main = React.createClass ({
render () {
return (
<div>HELLO</div>
);
}
});
export default Main;
i dont see the need to create factory for this one.

Answer 2

I was getting the "calling a React component directly" warning too and fixed it by yielding a promise
function *() {
this.body = yield new Promise(resolve => {
Router.run(routes, this.req.url, Handler => {
resolve(React.renderToString(<Handler/>));
});
});
}