state

问题 Im having trouble with the following code: My compnent: class Landing extends Component { state = { loginMethod: '', tournamentCode: -1, } } My Const: const Code = () => ( <div className="" style={{marginTop: 20}}> <input className="" style={{lineHeight: 1, height: 30, border:0, paddingLeft: 5}} placeholder="Tournament Code" onChange={e => this.setState({tournamentCode: e.target.value})} /> <Link to="/App"> <button className="" style={{marginLeft: 10, border: 0, outline: 'none', background: '

问题 So I have a parent and children component. Parent passes whatever is typed in the search bar as a prop to the children. then the api fetch should be executed, I see the fetch object in the console. I'm having difficulties setting the children state from the parent. Any tips would be appreciated, thank you and happing coding :D class HelloComponent extends React.Component { render () { return <h1>Github API repositories </h1>; } } class Parent extends React.Component { constructor (props) {

问题 When I run the following code compiled for iOS14 on iOS14 sim or device, the updated @State variable "selection" doesn’t get passed to a view displayed as .sheet(… The exact code runs OK on iOS 13.5 sim or 13.6 device The code runs as expected on iOS 14, if I place somewhere in the view a Text(“”) and display the variable being updated. It seems that only if I display the value, the .sheet get's rendered again updating the MyView(tenum: selection) with the correct value. In the code below

问题 I have a simple grid, that takes more space than the screen real-state, and can be scrolled up and down. Each cell has an onTap() method that changes the cell color. The problem is that once I scroll the changed cell out of view, the state is not kept. Any ideas? class GridWidget extends StatefulWidget { @override _GridWidgetState createState() => new _GridWidgetState(); } class _GridWidgetState extends State<GridWidget> { @override Widget build(BuildContext context) { Color cellColor =

问题 I have an actor in which I mutate the state using context.become: Here is the snippet: def stateMachine(state: State): Receive = { case a => { ... do something context.become(stateMachine(newState)) } case b => { ... do something sender ! state } case c => { ... do something context.become(stateMachine(newState)) } } My IntelliJ says that my stateMachine(...) function is recursive. Is this a problem? Should I be concerned? Is there something fundamentally wrong with my approach in the above

问题 I have CSV files with comments that give column names, where the columns change throughout the file: #c1,c2,c3 a,b,c d,e,f #c4,c5 g,h i,j I want to provide a way to iterate over (only) the data rows of the file as Maps of column names to values (all Strings). So the above would become: Map(c1 -> a, c2 -> b, c3 -> c) Map(c1 -> d, c2 -> e, c3 -> f) Map(c4 -> g, c5 -> h) Map(c4 -> i, c5 -> j) The files are very large, so reading everything into memory is not an option. Right now I have an

问题 I'm making a very simple application where you can click on square divs to change their color from white to black. However, I'm having trouble. I'd like to use the onClick function to allow a user to click on a square to change its color, but it doesn't seem to be working. I've tried using spans and empty p tags, but that doesn't work either. Here is the code in question: var Box = React.createClass({ getInitialState: function() { return { color: 'white' }; }, changeColor: function() { var

问题 I'm making a very simple application where you can click on square divs to change their color from white to black. However, I'm having trouble. I'd like to use the onClick function to allow a user to click on a square to change its color, but it doesn't seem to be working. I've tried using spans and empty p tags, but that doesn't work either. Here is the code in question: var Box = React.createClass({ getInitialState: function() { return { color: 'white' }; }, changeColor: function() { var

问题 I have a problem keeping the state of my buttons - say Button1.setActivated(true) . When orientation is changed this is forgotten and it is not reactivated or shown as activated. I guess I could use IFs to test the status of Button state, store it in a variable and then return it with onSaveInstanceState/onRestoreInstanceState. And then add more checks on each button when it is recreated. But that seems a massive convoluted way of doing things. Surely there will be a better way to do this? I

问题 I'm trying to find the best way to save the state of a simple application. From a DB point-of-view there are 4/5 tables with date fields and relationships off course. Because the app is simple, and I want the user to have the option of moving the data around (usb pen, dropbox, etc), I wanted to put all data in a single file. What is the best way/lib to do this? XML usually is the best format for this (readability & openness), but I haven't found any great lib for this without doing SAX/DOM.