'[Vue warn]: Duplicate keys detected: x. This may cause an update error
I keep getting an error when I add an item to the array which has duplicate id.
i.e.
active_widgets:Array[4]
0:Object
id:1
name:"Text Blocks"
selected:false
set:false
1:Object
id:3
name:"Bibliographies/References"
selected:false
set:false
2:Object
id:1
name:"Text Blocks"
selected:false
set:false
3:Object
id:2
name:"Free Text"
selected:"Test"
set:false
In my scenario, 'id' element may be duplicate because the user can have the same widget on the page multiple times. I want to know if I can suppress or remove the warning that VueJS keeps throwing in the console.
Solution 1:[1]
Same key for different v-for
loops causing this warning. You can avoid this using different key for different v-for
loops.
<div v-for="(item, i) in items" :key="i"></div>
<div v-for="(item, i) in items2" :key="'A'+ i"></div>
<div v-for="(item, i) in items3" :key="'B' + i"></div>
Here, A
and B
are just sample characters. You can basically use any character instead of those (just for uniqueness).
Solution 2:[2]
An alternative method:
Nesting the v-for
elements inside any other element also seems to work.
<div>
<div v-for="(item, index) in items" :key="index"></div>
</div>
<div>
<div v-for="(item, index) in items2" :key="index"></div>
</div>
Solution 3:[3]
You need to bind to the key
with a unique value. Not doing so will cause problems in your application when a change in data for a component with one key updates that component and the other component with the duplicate key.
You should assign a unique key property to each of the items in the active_widgets
array and then bind the key to that property.
Without seeing any of your code, I don't know what your unique use case is. But here are a couple ways you could add a unique key property to the items in your array.
Here's an example doing that in the created
method.
created() {
this.active_widgets.forEach((item, index) => this.$set(item, 'key', index));
}
If you need to add a unique key when an item is added to this array, you could maintain a counter and increment it each time an addition is made:
let WidgetCount = 0;
export default {
data() {
return { active_widgets: [] }
},
methods: {
addWidget(id, name) {
this.active_widgets.push({
id,
name,
selected: false,
set: false,
key: WidgetCount++
})
}
}
}
Solution 4:[4]
<template v-for="it in items">
<li :key="it.id + '-name'">{{it.name}}</li>
</template>
Solution 5:[5]
<div v-for="(data, index)" in active_widgets" :key="index">
{{data.id}}
{{data.name}}
{{data.selected}}
{{data.set}}
</div>
Solution 6:[6]
you can use this example
<template>
<div >
<div v-for="categori in blogs" id="blog-body" :key="categori.title" >
<h2 >{{categori.title}}</h2>
<h3>{{categori.contact }}</h3>
</div>
</div>
</template>
<script>
export default {
data(){
return{
blogs:[
{title:'this is title 1',contact : ' this is contact for test javascript'},
{title:'this new title ',contact : ' this is contact for vue'},
{title:'this is new title 2',contact : ' this is contact for vue js'}
]
}
},
}
</script>
Solution 7:[7]
I solved this by creating a unique key function to add keys to each of my arrays. Then using it in v-for as the key...
<div
class="postBlob"
v-for="{
key,
user,
post,
dateTime
} in localPostData.slice().reverse()"
:key="key"
>
<strong class="userBlobIndy">{{ user }} </strong>
<h2 class="postBlobIndy">
{{ post }}
<p>{{ dateTime }}</p>
</h2>
</div>
Sources
This article follows the attribution requirements of Stack Overflow and is licensed under CC BY-SA 3.0.
Source: Stack Overflow
Solution | Source |
---|---|
Solution 1 | David Wolf |
Solution 2 | W4G1 |
Solution 3 | |
Solution 4 | dippas |
Solution 5 | Gary Bao é²æ˜±å½¤ |
Solution 6 | hoseinsalimi |
Solution 7 | Dharman |