@bigfishtv/cockpit/src/components/form/AppendButton.js

import PropTypes from 'prop-types'
import React, { Component } from 'react'
import { withFormValue } from '@bigfishtv/react-forms'

import Button from '../button/Button'
import newId from '../../utils/newId'

@withFormValue
export default class AppendButton extends Component {
	static propTypes = {
		item: PropTypes.func,
		onAdd: PropTypes.func,
	}

	addItem = () => {
		const Items = (this.props.formValue.value || []).slice()
		const item = this.props.item ? this.props.item() : {}
		item.id = newId()
		Items.push(item)
		const formValue = this.props.formValue.update(Items)
		this.props.onAdd && this.props.onAdd(formValue.select(Items.length - 1))
	}

	render() {
		const { formValue, item, onAdd, ...props } = this.props
		return <Button {...props} onClick={this.addItem} />
	}
}