How should we handle a v-for bined with a v-if in this exemple:
Here my data.json:
[
{
image: 'foo.jpg'
},
{
image: 'foobar.jpg',
video: 'bar.mp4'
},
{
image: 'barfoo.jpg'
}
]
In my vue template, I'd like to render something like this:
<div v-for="(item, key, index) in data" : key="index">
<img :src="item.image">
<video v-if="!!item.video" :src="item.video"></video>
</div >
But as the documentation say, we should avoid v-if with v-for and instead use a puted value. But there I need to render the image even if the json entry doesn't have a video.
That's not a big deal, I've find a solution but I'd like to know the best way to handle this.
How should we handle a v-for bined with a v-if in this exemple:
Here my data.json:
[
{
image: 'foo.jpg'
},
{
image: 'foobar.jpg',
video: 'bar.mp4'
},
{
image: 'barfoo.jpg'
}
]
In my vue template, I'd like to render something like this:
<div v-for="(item, key, index) in data" : key="index">
<img :src="item.image">
<video v-if="!!item.video" :src="item.video"></video>
</div >
But as the documentation say, we should avoid v-if with v-for and instead use a puted value. But there I need to render the image even if the json entry doesn't have a video.
That's not a big deal, I've find a solution but I'd like to know the best way to handle this.
Share Improve this question edited Jul 14, 2022 at 1:41 tony19 139k23 gold badges277 silver badges347 bronze badges asked Feb 4, 2019 at 14:46 Allan RaquinAllan Raquin 6138 silver badges26 bronze badges1 Answer
Reset to default 7I think that you are misunderstanding the documentation. In this instance, it makes sense to use both v-for and v-if because you are always going to render at least the <img> and you might render the <video>. The documentation is trying to show that you should pre-filter a list of items if the v-if and v-for are on the exact same element.
The example the docs are showing are trying to get you to cut a list that would show only only 2 of the 3 total elements down to just 2 elements and letting the puted prop tell you when there are more. Otherwise you have to iterate through the entire list every time you need to re-render.
Consider this difference:
// An array of 1000 items but only 1 has a video element
const data = [0...999];
data.push({
image: "some.jpg",
video: "some.mp4"
});
<!--
We always render 1000 items but only some will have video
-->
<div
v-for="(item, key, index) in data"
:key="index">
<img :src="item.image">
<video v-if="!!item.video" :src="item.video"></video>
</div>
<!--
We have to visit 1000 elements but
only 1 will actually end up rendering
-->
<div
v-if="!!item.video"
v-for="(item, key, index) in data"
:key="index">
<img :src="item.image">
<video :src="item.video"></video>
</div>