SolidJS•2mo ago

changing route with useNavigate() causes onMount() of the child route to be fired twice

Hey, i have a problem that i cant wrap my mind. When i load my Route in a new window/tab or with F5 the onMount() function of one of my children is only fired one. But when i use useNavigate(), then onMount() gets fired twice. Why could that be? I am working on replicating the bug.

1 Reply

Karl•2mo ago

Okay the issue arises because of <Suspense>

// App.tsx
<Router>
        <Route path='/' component={Home}></Route>

        <Route path='/test' component={Test}>
          <Route path='/hallo1' component={Hallo}></Route>
          <Route path='/hallo2' component={Hallo2}></Route>
        </Route>
 </Router>

// App.tsx
<Router>
        <Route path='/' component={Home}></Route>

        <Route path='/test' component={Test}>
          <Route path='/hallo1' component={Hallo}></Route>
          <Route path='/hallo2' component={Hallo2}></Route>
        </Route>
 </Router>

function Test(props: any){

    async function fetchTest(){
        return new Promise(async (resolve, reject) => {
    
            setTimeout(() => {
                resolve('nice')
            }, 2000)
        })
    }

    const [ok, {mutate, refetch}] = createResource<any, any>(fetchTest)

    return(
        <div>
            <Suspense>
                
                <p>{ok()}</p>
                {props.children()}
            </Suspense>
            
        </div>
    )
}

function Test(props: any){

    async function fetchTest(){
        return new Promise(async (resolve, reject) => {
    
            setTimeout(() => {
                resolve('nice')
            }, 2000)
        })
    }

    const [ok, {mutate, refetch}] = createResource<any, any>(fetchTest)

    return(
        <div>
            <Suspense>
                
                <p>{ok()}</p>
                {props.children()}
            </Suspense>
            
        </div>
    )
}

function Hallo(props: any){
    const navigate = useNavigate()

    onMount(() => {
        console.log('hallo1')
    })

    return(
        <div>
            <button
                onclick={(() => {
                    navigate('/test/hallo2')
                })}
            >/hallo2</button>
        </div>
    )
}

function Hallo(props: any){
    const navigate = useNavigate()

    onMount(() => {
        console.log('hallo1')
    })

    return(
        <div>
            <button
                onclick={(() => {
                    navigate('/test/hallo2')
                })}
            >/hallo2</button>
        </div>
    )
}

function Hallo2(props: any){
    const navigate = useNavigate()

    onMount(() => {
        console.log('hallo2')
    })

    return(
        <div>
            <button
                onclick={(() => {
                    navigate('/test/hallo1')
                })}
            >/hallo1</button>
        </div>
    )
}

function Hallo2(props: any){
    const navigate = useNavigate()

    onMount(() => {
        console.log('hallo2')
    })

    return(
        <div>
            <button
                onclick={(() => {
                    navigate('/test/hallo1')
                })}
            >/hallo1</button>
        </div>
    )
}

Now when i click the buttons with onclick -> useNavigate(), the onMount() function of the subroutes gets executed twice. Any idea how to solve this? Okay the problem was solved for me by usind <Show when={!ok.loading}> instead of Suspense. I still cant quite wrap my mind around it. Can someone hint me to resources to understand it?

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changing route with useNavigate() causes onMount() of the child route to be fired twice