I have issue with having keep-alive actually keeping components alive.
Component that is being rendered in router-view have async fetching after component is mounted. My issue is that after the first time component shows up, when I render other component in that very same router, and then go back, then first component rerender as normal instead of keeping fetched data as it was.
I checked hooks and besides activated and deactivated also created hook fires which I suppose shouldn't be the case beyond first render. Also when I switch components destroyed hook fires which also shouldn't happen.
.container-fluid
.row.wrapper
aside.col-12.col-sm-2.p-0
nav.navbar.navbar-light.navbar-expand-sm.align-items-start.flex-sm-column.flex-row.text-uppercase#navbar1
a.navbar-toggler(href='', data-toggle='collapse', data-target='.sidebar')
span.navbar-toggler-icon
.collapse.navbar-collapse.sidebar
ul.flex-column.navbar-nav.w-100.justify-content-between
li.nav-item
router-link.nav-link.pl-0(to='candidates' data-toggle="collapse" data-target=".navbar-collapse.show")
font-awesome-icon.fa-fw.mr-2(:icon="iconTachometer")
| Dashboard
main.col.bg-faded.py-3
.card
.card-body
keep-alive
router-view(:key="$route.fullPath")
Okay, I found the answer - and my apologies because turned out my question wasn't fully informed.
First thing - the component in question was already nested within another router-view so what I was actually doing was nesting one in another.
Therefore, to keep alive that nested/child router-view parent router-view also has to be wrapped with keep-alive.
Based on answer here: https://forum.vuejs.org/t/how-to-use-keep-alive-with-nested-router-component/46813/4
See Special Attributes - key:
It can also be used to force replacement of an element/component
instead of reusing it. This can be useful when you want to:
Properly trigger lifecycle hooks of a component;
Trigger transitions.
If you bind key to $route.fullPath, it will always force a replacement of the <router-view> element / component every time a navigation event occurs. So just remove :key.
Related
I currently have the following problem with nested <router-view>s in my app and I want to know if this is even the right way to do it.
I have a navigation.vue route component with child routes configured in the router.
In this component, I have multiple <router-view>s (in a v-for loop).
Every router-view has its own link and if you click on it, the clicked container which holds the router-view will start a transition and reveal the content (the page.vue component).
To fire the transition before confirming the navigation, I listen for the beforeRouteUpdate() hook.
However, I now want to add other navigation components inside this navigation, so that I have something like that:
<navigation>
<page/>
<page/>
<navigation>
<page/>
<page/>
</navigation>
<page/>
</navigation>
The hook to open the sub-navigation seems to work - but if I try to open a page on the second level, the navigation component can't get the $refs that belong to itself. I see the beforeRouteUpdate() hook of the first level navigation being called. I think that's to be expected because it's still in the background, holding the second level navigation and its pages.
What can I do to only use the functionality of the second level navigation when it's opened?
Should I make some checks in the beforeRouteUpdate() hook, and are they both fired?
I'm probably confused because I don't know if the component is being reused or something - in my understanding it should be a second instance of the component.
I'm also using <keep-alive> around the <router-view>s - so if that's a problem and things work differently with that, I'd also be glad to get a hint.
Thanks!
I’m not sure if this will fix your problem but in this vue school video they talk about the Vue Router not always picking up on changes if the same component is being used. You can handle it by adding a key to the router-view like <router-view :key=“$route.path” />. Then any change to the path will trigger a reload of the component. Maybe you can experiment with adding keys to your nested <router-view>s?
I solved it this way:
Both beforeRouteUpdate() hooks are called, so I had to make sure which of the existing navigations should do the work. The upper level navigations skip the hook.
I also needed some checks to only render the navigation in the <router-view> if it is in the $route.match array of the current route.
I’m using Vue & Vuetify to create my app. With vuetify I’m using v-expansion-panels to create an accordion style display. Each v-expansion-panel itself contains a custom component.
I have noticed these components are not created until the expansion panel is clicked for the first time. After that, using keep-alive allows all reactive properties and methods of the child component to be active (this is my desired behavior).
How can I force the child components to be created when the parent is created? This, any method triggered in the created() lifecycle hook of a child component should fire when the parent is created.
This Codepen is an example of the current behavior. Note: be sure to look at the console when you click the panel.
If you think about it, it actually makes sense to lazy load content of expansion panels since it is useless work if the user never opens them anyway. So probably the thing you try to accomplish has some better approach, but if you still like it then my advice is to find a way of programatically opening / closing the panel (as seen here) and quickly open it and close it when rendering parent component. In this way, you will have your child component created and the UI will remain the same.
A Vuetify solution should be achievable by adding the eager prop to a v-expansion-panel-content element in the Expansion Panel. This should force any components or content contained within the v-expansion-panel-content element to render on mounted.
<v-expansion-panels v-model="panels">
<v-expansion-panel>
<v-expansion-panel-content eager>
<custom-component />
</v-expansion-panel-content>
</v-expansion-panel>
</v-expansion-panels>
I have to code a web application and the most important element is the q-tree. I'm already able to load and show data (passing an array called list), but I want that all nodes are expanded.
The vue.js examples of the official documentation show that you're be able to do this with the 'default-expand-all' attribute but this isn't working for me.
It only shows me the root node with an arrow, where I have to expand the children nodes manually.
<q-tree
:nodes="list"
:selected.sync="selected"
#update:selected="onSelectionChangedNode"
node-key="NodeNr"
label-key="NodeTxt"
default-expand-all
></q-tree>
Taking a cue from the accepted answer, I realised that the dom has already been created with the tree component on first render.
In my use case, I want to update the Tree when data comes back from the server.
So, I had to force it to re-render with the expanded functionality using:
this.$nextTick(function () {
this.$refs.nodes.expandAll();
})
The nextTick function will update the dom in the next window of execution, by which time the nodes will get expanded by calling the expandAll function.
And NB: For those confused by the astericks on the ref attribute or how to add it to the component, here goes:
<q-tree :nodes="list"
:selected.sync="selected"
#update:selected="onSelectionChangedNode"
node-key="NodeNr"
label-key="NodeTxt"
ref="nodes"
>
Solved my problem as following:
I have added a ref attribute to the QTree DOM Element which makes it possible to access predefined methods of QTree API.
<q-tree
:nodes="list"
:selected.sync="selected"
#update:selected="onSelectionChangedNode"
node-key="NodeNr"
label-key="NodeTxt"
**ref="nodes"**
>
The function I have been using is expandAll().
updated() {
this.$refs.nodes.expandAll();
}
The most important thing for me was, I had to find out which lifecycle hook was the right one for me. The update() hook was the one I was looking for.
The reason:
Called after a data change causes the virtual DOM to be re-rendered and
patched.
The component’s DOM will have been updated when this hook is called, so you
can perform DOM-dependent operations here.
The default-expand-all is only applied on the first rendering of that Component.
So if your Component renders when the nodes aren't assigned they wont expand if assigned afterwards.
https://v1.quasar-framework.org/vue-components/tree
You have to work with scoped slots and an expanded attribute if you dont have the nodes on first rendering.
Let's suppose I have a component called FirstPage, which is my default route, now FirstPage triggers an asynchronous call, with the help of an action of the vuex store, to be made each minute to a backend Api (it's triggered when the component is loaded as a route), now let's say I go to an about route that goes to an About component, is FirstPage still making the calls?
Edit:
I'm not developing an app with that yet, so I can't provide examples.
It's on my interest to know the behavior in these cases of the router, because whenever I change the route I would want to stop making the constant calls (as they won't be necessary).
The reason is that Depending on this I'd have to switch tooling for a project I have in mind.
In general, a component's instance will be destroyed when you navigate away from it. However, there are two exceptions to this ..
When you use routes with params. From the Vue Router docs
One thing to note when using routes with params is that when the user navigates from /user/foo to /user/bar, the same component instance will be reused. Since both routes render the same component, this is more efficient than destroying the old instance and then creating a new one. However, this also means that the lifecycle hooks of the component will not be called.
When you wrap your router-view component within a keep-alive element. Since the <router-view> is essentially a dynamic component.
Generally Vue does a very good job of housekeeping and cleaning up after a component's instance when it gets destroyed. But sometimes you'll have to do some manual cleanup, especially if you use some kind of external library. This is usually handled in the beforeDestroy hook of an instance's lifecycle.
In normal conditions, any logic/scripts/etc done at creation inside said component will be "purged" on the on destroy/close hooks (not only pertinent to vue but seen in lots of other tools), if there is a need to persist something then it should be in a higher scope (or other solution)
Any script written for the respective component only runs if the component is rendered in page. Once you go to about component replacing the previous component then previous script wont run.
you can make a parent component with a router-view and load in your page you always want to get loaded, so your FirstPage component, but this component should just have logic behind it, and no html because otherwise you will always see that rendered. Router-view the page you want to display the real html and stuff. I hope you get the idea, if not i could make an example for you. Goodluck.
Let's say I have a <router-view> showing one component (A) and through a <router-link> this component will be replaced by another one (B).
Both components have their own beforeCreate and beforeDestroy hooks. I'd expect that if I navigated from A to B the sequence of events would be:
A.beforeDestroy
B.beforeCreate
But after doing some tests it appears to be the exact opposite: B.beforeCreate is always called before A.beforeDestroy.
Is that correct? And if it's correct, why is it this way? Doesn't make sense to me...
In my case all those hooks interact with some common data, so I'm facing race conditions here... Any suggestion on how to deal with that? I need to get some things done before creating B that cannot be started before destroying A...
Before the previous component is destroyed, the next component will be created first.
The purpose is obviously to avoid flickering as the view transitions from the previous component to the next component.
If the behavior you wanted is to make sure that a code should be executed always after the beforeDestroy and not before, you should use the mounted or beforeMount lifecycle hook.