CalendarDemo | 仿美团酒店预订日期选择

Your code does not create a new appointment, you only retrieve the Items collection. Assuming the "Schedule" folder is a suborder of the Calendar folder, the code needs to be

• convert every class method func to an inner function (either using function func() {} or using const func = () => {})
• convert every attribute attr in your state to a const [attr, setAttr] = useState() call. Then replace every call to this.state.attr with attr and every call of this.setState({attr: newValue}) with setAttr(newValue)
• Keep your render() function mostly as-is, just remove the outer function, remove every this. prefix when referencing function and replace every reference to this.state as described above
• (Not present in your example): Replace componentDidMount with useEffect
• Replace class CalendarDemo extends Component with function CalendarDemo() (use arrow-syntax, if you like)

I have created a working plunker to demonstrate it should work. It is also working on the PrimeNG demo page, so it has probably something to do with external implementation details of your application.

app.component.ts