Checkout UI extension line item is not updating properly

Shopify Apps
5

Sooo,
I found the issue and a workaround:

The problem is that it seems they both run in the same step (react hooks) and the update is not set properly this way. My hotfix was to just create a dummy state to handle this:

const cartLines = useCartLines()
const lineChanger = useApplyCartLinesChange()
// we create a dummy State variable to update everything when we want to
const [ useless, setUseless ] = useState(0)
useEffect( () => { // do something with cartLines here }
  , [useless]) // will trigger on any change to the dummy

// for example, this will empty the cart one by one, reloading once inbetween

useEffect( () => {
  lineChanger( { /*change*/ }).then( () => {
    setUseless( (i) => i+1 ) // set the useless State so the component will update
  })
}, [useless] )