ideomatic-react-formbuilder.jsx

const Input = props => {
  return <input {...props} />;
}

const FormRow = props => {
  return <div className="formRow">{props.children}</div>;
}

const makeBindFn = (formId, formComp) => {
  return inputName => {
    return {
      onChange: (e) => { formComp.handleInputChange(inputName, e.target.value) },
      defaultValue: formComp.state[inputName]
    };
  };
}

class Form extends React.Component {
  constructor(props) {
    super(props);

    this.state = {
      email: "user@user.com"
    };
  }

  handleInputChange(inputName, newVal) {
    this.setState({ [inputName]: newVal });
  }

  render() {
    const bind = makeBindFn("login-form", this);

    return (
      <FormRow>
        <Input {...bind("email")} someProp="someVal" />
        <Input {...bind("password")} someProp="anotherVal" />
        <pre>Form model: {JSON.stringify(this.state)}</pre>
      </FormRow>
    );
  }
}