Suppose you have to render paginated data.
A paginator component should appear above and below the data table rendering exactly the same output.
The most basic approach would be declaring the paginator component twice - one above the data and one below. But the resulting vnodes (and even the dom fragment) of the paginator component instances will be equal. Both paginator instances would compute (also twice !) completely equal vnode and dom fragments.
I would like to avoid duplicated vnodes/dom node rendering and computation time. Basically compute everything once and duplicating the resulting nodes would be the ideal goal.
My current known options:
Hacking something like a single Vue pagination component and cloning its resulting DOM output to somewhere else sounds like a bad idea because of potential Vuiejs $ref and dom/vuejs event handling issues. So this is actually no option.
What about cloning the vnode of the first pagination component instance and reuse it for the second instance ? Is that the way to go ?
What is the best option ?
Are there any better approaches to match my expectations ?
Related
After trying to find solution to this issue for hours on various forums i am posting this here.
So i have two components. 1) App and 2) Todo. Both renderes a list and i can complete items so there will be two lists one for incomplete items and one for complete items. you can click on item and it will be gone to complete items list.
So in my example you can see i am using same component but with two diffreent ways to give data to component. one using API and one using native js Data. in both cases it renderes but with api i can click on list item and it will be gone to completed list but with javascript array example it doesn't work. i am completely amazed with this because component is same. how it can affect like that.
many answer here do tell me that computed properties are not reactive as they are cached but what’s the solution to that ? i can put data variable but then the first case of api will not work because time it takes to fetch it. so please help me with this one.
complete code at sfc playground
You have reactivity issues the computed property probably expects that value to be constant because you provide a non-reactive array from the parent.
I think you have 2 options here:
you either provide a reactive prop from parent
or you set a local data attribute in the child-component so that vue will know that it can change
Your fiddle didn't work for me so I copied your code to codesandbox, I have both examples there but commented out the first solution, there you basically simply add the array to the data object and reference that in the code.
Second solution you can add a mounted hook to define reactiveAssignments to your data in the child component this way it will have the same reference so that's why it would work that way.
I think the first solution is simpler, but it is really up to which one you prefer.
You can check the solutions here in my codesanbox
A better approach could be though by setting up component events instead of v-models in the child you should use it in the parent because this way you are directly modifying the props. You can read more about this here: https://vuejs.org/guide/components/events.html#usage-with-v-model
I have this weird bug with a slot that is unreliable in certain unknown cases.
Components
There are 3 hierarchical components.
The grandchild (headlessTable), which offers a slot named arrayValue.
The child (collapsableCard), which passes the slot between grandchild and parent.
The parent (orderDataCard), who decides to render a link for that slot.
Problem: Instead of rendering the link of the parent, the default slot html of the child is being rendered when new data is loaded.
Datastructure (orderDetails)
process (obj)
mark (string)
common (obj)
additionalArguments (array)
category (string)
type (string)
name (string)
value (string)
salesOrganisation (obj)
invoices (array)
invoiceAgreementId (string)
paymentType (string)
Reproduction
Stackblitz or Codesandbox
Please look at the field additionalArguments, it contains a link.
Press ALT+M to simulate fetching new data. Now, instead of rendering a link, the default slot html for that named slot is rendered instead.
You can press ALT+J to load the original data, but this time there's no link.
Initial data (ALT+J)
Loaded data (ALT+M)
Type
Equal value
mark
str
false
common
common
obj
true
salesOrganisation
salesOrganisation
obj
true
invoices (empty)
invoices
arr
false
How 2 resolve
if you uncomment line 68 in app.js (or line 73 in App.vue if you're on codesandbox), which is the field called mark
if invoices is not initially empty in app.js
if mark is removed from html in orderDataCard
if salesOrganisation is removed from html in orderDataCard
if the html in the v-for template section for invoiceItems is empty in orderDataCard
Obviously, these are not solutions.
Notes
In any case, there is no dependence or anything between any of the fields, so it's hard for me to understand why this happens and I suspect this to be a bug with vue. I already created an issue for this. However, devs won't look at the reproduction, because they think it's not minimal as #lines > 100. As soon as I delete any more meaningful lines, the bug is resolved and the removed code is not faulty, so it's very frustrating to work on this. I could still remove lines that are not meaningful, but that would make it more difficult for everyone involved to understand what data is being rendered.
Is anyone able to acknowledge the fact that this is a problem with vue and that the code is not reducible OR (I would prefer this) is anyone able to fix this?
The problem is linked to Vue handling of multiple instances of the same component. In OrderDataCard.vue you have two instances of Collapsable-Card without unique keys. In this case:
Vue uses an algorithm that minimizes element movement and tries to
patch/reuse elements of the same type in-place as much as possible.
I don't quite know how these algorithms work, and why, apparently, it reused the second instance (without a defined slot content), but, setting a unique key for these components solved the issue.
See the working code sandbox: https://codesandbox.io/s/admiring-hamilton-5ytpp?file=/src/components/OrderDataCard.vue:133-149.
Note: I couldn't trigger keyboard events in my browser, so I triggered them on button click.
This may not be the solution, but could help find it:
Objects
I noticed you are working with objects and turning them into arrays. Objects properties can be problematic to work with, because unlike arrays updated properties are not propagated. This is a problem with JavaScript, not Vue. Vue was only possible because of observers introduced, but objects are still not part of that.
You might run into problems when an object is partially updated.
I would suggest looking at Vue.set.
Old code of mine invokes it explicitly by window.Vue.set() for changes in object properties so Vue can propagate them correctly.
That is kind of a bug in Vue, but again stems from JavaScript itself.
Computed arrays
I'm not entirely sure but the computed arrays don't save the above issue with working with objects.
I would go the safe route and use Vue.set() when updating objects and object properties. You can still use the computed arrays then.
Otherwise the obvious: Make real arrays out of the objects instead of working with objects half the time.
this.process
Is there a good reason you are using this.process explicitly instead of the component's props? Or is that a component from a library?
Slots
Have you tried the exact same code but without using the collapsable-card? Just output the link itself? It might point to slot problems in the collapsable-card component. Maybe also partially because of the objects thing from above.
I'm using Vue and I wonder if I have a list of components (50 button with the very same function within each one of them) - will Vue recognize it as a repetetive code and reduce to one function that all those 50 button will use or each one will compile it's own function while bundling?
will Vue recognize it as a repetetive code and reduce to one..
No. Vue will not scan your code for similar code and try to optimize it.
However, when Vue is updating a list of elements rendered with v-for, by default it uses an “in-place patch” strategy. If the order of the data items has changed, instead of moving the DOM elements to match the order of the items, Vue will patch each element in-place and make sure it reflects what should be rendered at that particular index.
Maybe this is what you are confused with? This is not the same as the question you are asking, but the closest thing vue would do "magically".
If you have 50 similar buttons, I would advice you to rather take advantage of props, slots and slot scopes to only have one button component that you can tweek in place where you need them to be different. 50 alike buttons sounds like a bad pattern.
I'm writing an app in Vue and I have a really hard time understanding the component hierarchy, namely the parent-child relationships and how to pass data around.
I have a view that contains a map which in turn has some navigation controls and options that are overlayed on top of the map. Now, I want these controls to manipulate the map WITHOUT having to nest the buttons inside the actual maps as it will cause severe display issues (for example, clicking on a zoom button falls through the button and also clicks the next element under it).
My app looks like this:
Mapview
Map
Controls
Options
Optionpanel1
Optionpanel2
...
Now, a HTML input element in Optionpanel1 needs to control something in the Map, which is not actually it's parent component. Also, some data from Map needs to be passed down to Optionpanel1 so it would know what to control. To make matters worse, something in Options also needs to pass something down to Optionpanel1, so, even though event bus would allow communication upwards, it would not solve that I need to pass data from parents to indirect children and also components that are not it's children.
I can actually pass the required property down the line if I nest the Options inside Map and pass it down with :myProp="prop" and then in Options, declare it in props and bind to Optionpanel1, where it is again declared as a prop. But as I mentioned earlier, nesting elements that I do not want to be nested in a visual sense causes massive issues like mouse click falling through. Do elements even need to be nested inside eachother in order to define parent-child relationship?
I would want components to exchange read-only data without Y being a child of X in the DOM. Also, even if nesting components like this would not cause visual issues, does it not seem very annoying to have to register and bind it in every component along the way?
I don't understand why is it so difficult to simply read something from another component. It's starting to seem that Vue is causing a problem that it's supposed to solve? Am I missing something here or am I looking at this in a completely wrong way?
Thanks in advance.
Basically you have 2 options to control complex components:
Handle the actions in your so-called "smart component" (in terms of React), which is the common ancestor for the controlling and controlled components. It's a pretty good solution for small components, but that's not the case.
To separate common logic and data in a Vuex store. I'd recommend you doing this.
I am creating a Vue component ("Polar") to layout divs in a circular pattern. It does so setting the inline styles.
Now, I am having a weird issue when I use the component. It happens only under a very specific set of circumstances:
I create multiple instances through v-for
The Polar component is a "functional" component
I pass the props as a referenced object (inline works fine!)
The propsObject contains a nested StylesObject
The custom Styles object gets merged as the first parameter of ObjectAssign()
What happens? All the instances in the v-for take on the value of the last item, like a closure was broken.
The code is a bit much to display here, so I have a codesandbox and github. The first test shows the issue: all items are displayed on top of each other. The second test demonstrates that I can pass the exact same propsObject, only inline, and it works. Reversing the arguments in Object.assign also makes it work, as does converting the component to a normal/non-functional one.
I suspect this is some sort of Vue bug (or at least undocumented behavior).
Quick answer:
Object.assign will change the first parameter (=target object). This caused my settingsObj to take on the other settings every time, until it had the settings of the last instance.
Easily resolved by changing
Object.assign(props.settingsObj, {setting: val, })
into
Object.assign({}, props.settingsObj, {setting: val, })
Sorry for blaming Vue, all my fault. Not exactly sure why this only happens with functional components, but it must be related to normal components being isolated in their own Vue instance.