setstate

问题 I am using the method in this question to change the body of a Scaffold in flutter: Flutter Drawer Widget - change Scaffold.body content The method described works perfectly. Now I would like just the drawer to automatically close after the users taps on one of the items. I tried using the Navigator.pop() method, but it pops the entire screen, not just the drawer. It leaves me with a totally black screen. Any suggestions? 回答1: Are you using exactly Navigator.of(context).pop() ? I cannot

问题 I am using the method in this question to change the body of a Scaffold in flutter: Flutter Drawer Widget - change Scaffold.body content The method described works perfectly. Now I would like just the drawer to automatically close after the users taps on one of the items. I tried using the Navigator.pop() method, but it pops the entire screen, not just the drawer. It leaves me with a totally black screen. Any suggestions? 回答1: Are you using exactly Navigator.of(context).pop() ? I cannot

问题 How to get data from props and be sure that data arrived properly. My issue is that in my class component I receive alarms from props and then I want to render table with the alarms, props sets asynchronously and I want to be sure that the data arrived and that I will be able to set a state. Below is my not nice try to solve it, but does not work (both console.log shows empty array): componentDidMount() { this.setState({ startDate: moment() .subtract(30, 'days') .startOf('day'), endDate:

问题 How to get data from props and be sure that data arrived properly. My issue is that in my class component I receive alarms from props and then I want to render table with the alarms, props sets asynchronously and I want to be sure that the data arrived and that I will be able to set a state. Below is my not nice try to solve it, but does not work (both console.log shows empty array): componentDidMount() { this.setState({ startDate: moment() .subtract(30, 'days') .startOf('day'), endDate:

问题 My current state has this: state = { items : [{id: 1, text: 'test words'}, {id: 2, text: 'another test'}] Here's my function to remove objects from the array, trying to avoid mutating state. handleRemove(passedInId) { const myItems = this.state.items const newArray = myItems.filter(item => item.id !== passedInId) this.setState(prevState => ({ items: prevState.items = newArray })) console.log('handle remove runned', passedInId, myItems, newArray) } It works perfectly but would like to know if

问题 my function looks like this: this.setState(prevState => ({ time : prevState.time + 1 }), function() { doSomethingWithNewState(this.state.time) }) is it correct to use await in this situation? like this: await this.setState(prevState => ({ time : prevState.time + 1 })); doSomethingWithNewState(this.state.time); 回答1: No this.setState doesn't return a promise. So you can't use await in this case. You need to use the callback. 回答2: As the previous answer mentioned, setState() does not return a

问题 What I did : I have integrated FCM (Firebase Cloud Messaging) in my flutter app. I shared the context and the setState() of each page in static variables with these two lines getting called in all the build functions of my pages : @override Widget build(BuildContext context) { StaticClass.currentContext = context; StaticClass.currentSetState = this.setState; return ... ; } I created a callback to handle the coming notifications when the app is running fcm.configure( onMessage: (){ StaticClass

问题 this.setState(prevState => ({ score: prevState.score + 10, rightAnswers: prevState.rightAnswers + 1, currentQuestion: setTimeout(() => { prevState.currentQuestion + 1 }, 2000) })) } On button click I change the state. My goal is to have a delay in currentQuestion state change, during which I want to show certain status messages, yet I want to update the score right away without delays. What's the proper way to do that? PS: This variant doesn't work, it's for the overall representation of what

问题 I have in flutter day and time page view, when the user click time setState the clicked time to the grey color, and setState the others to the transparent color, in this image you can see the selected date please note that the user can re select again so the old selection setState to the transparent color. 来源： https://stackoverflow.com/questions/60277469/how-to-make-day-and-time-list-horizontal-view-from-api-with-two-button-to-scroll

问题 I'm having issues getting one of my fields to pre-populate with info and be editable. I've tried moving around the code where it sets the field with the data and either it's blank and editable or shows the pre-populated data but the UI prevents me from editing it. The issue I'm having is with the bar field. Putting it in the constructor pre-populates the field with info but the UI is preventing me from editing it. Why? Where should this field be set or how can I fix it? Do I need to call