I know how to remove a list item from a Vue instance. However, when list items are passed to Vue ponents, how to remove a list item while keeping the ponents in sync with the list data?
Here is the use case. Consider an online forum with a Markdown editor. We have a Vue instance whose data are a list of saved ments fetched from a server. These ments are supposed to be written in Markdowns.
To facilitate edits and previews, we also have a list of ponents. Each ponent contains an editable input buffer as well as a preview section. The content of the saved ment in the Vue instance is used to initialise the input buffer and to reset it when a user cancels an edit. The preview is a transformation of the content of the input buffer.
Below is a test implementation:
<template id="ment">
<div>
Component:
<textarea v-model="input_buffer" v-if="editing"></textarea>
{{ preview }}
<button type="button" v-on:click="edit" v-if="!editing">edit</button>
<button type="button" v-on:click="remove" v-if="!editing">remove</button>
<button type="button" v-on:click="cancel" v-if="editing">cancel</button>
</div>
</template>
<div id="app">
<ol>
<li v-for="(ment, index) in ments">
<div>Instance: {{ment}}</div>
<ment
v-bind:ment="ment"
v-bind:index="index"
v-on:remove="remove">
</ment>
</li>
</ol>
</div>
<script src=".1.8/vue.js"></script>
<script>
let ments = ['111', '222', '333']
Vueponent('ment', {
template: '#ment',
props: ['ment', 'index'],
data: function() {
return {
input_buffer: '',
editing: false,
}
},
mounted: function() { this.cancel() },
puted: {
preview: function() {
// This is supposed to be a transformation of the input buffer,
// but for now, let's simply output the input buffer
return this.input_buffer
},
},
methods: {
edit: function() { this.editing = true },
remove: function() { this.$emit('remove', this.index) },
cancel: function() { this.input_buffer = thisment; this.editing = false },
//save: function() {}, // submit to server; not implemented yet
},
})
let app = new Vue({
el: '#app',
data: { ments: ments },
methods: {
remove: function(index) { thisments.splice(index, 1); app.$forceUpdate() },
},
})
</script>
The problem is that, if we remove a ment, the ponents are not refreshed accordingly. For example, we have 3 ments in the above implementation. if you remove ment 2, the preview of item 3 will still show the content of item 2. It is updated only if we press edit followed by cancel.
I've tried app.$forceUpdate(), but that didn't help.
I know how to remove a list item from a Vue instance. However, when list items are passed to Vue ponents, how to remove a list item while keeping the ponents in sync with the list data?
Here is the use case. Consider an online forum with a Markdown editor. We have a Vue instance whose data are a list of saved ments fetched from a server. These ments are supposed to be written in Markdowns.
To facilitate edits and previews, we also have a list of ponents. Each ponent contains an editable input buffer as well as a preview section. The content of the saved ment in the Vue instance is used to initialise the input buffer and to reset it when a user cancels an edit. The preview is a transformation of the content of the input buffer.
Below is a test implementation:
<template id="ment">
<div>
Component:
<textarea v-model="input_buffer" v-if="editing"></textarea>
{{ preview }}
<button type="button" v-on:click="edit" v-if="!editing">edit</button>
<button type="button" v-on:click="remove" v-if="!editing">remove</button>
<button type="button" v-on:click="cancel" v-if="editing">cancel</button>
</div>
</template>
<div id="app">
<ol>
<li v-for="(ment, index) in ments">
<div>Instance: {{ment}}</div>
<ment
v-bind:ment="ment"
v-bind:index="index"
v-on:remove="remove">
</ment>
</li>
</ol>
</div>
<script src="https://cdnjs.cloudflare./ajax/libs/vue/2.1.8/vue.js"></script>
<script>
let ments = ['111', '222', '333']
Vue.ponent('ment', {
template: '#ment',
props: ['ment', 'index'],
data: function() {
return {
input_buffer: '',
editing: false,
}
},
mounted: function() { this.cancel() },
puted: {
preview: function() {
// This is supposed to be a transformation of the input buffer,
// but for now, let's simply output the input buffer
return this.input_buffer
},
},
methods: {
edit: function() { this.editing = true },
remove: function() { this.$emit('remove', this.index) },
cancel: function() { this.input_buffer = this.ment; this.editing = false },
//save: function() {}, // submit to server; not implemented yet
},
})
let app = new Vue({
el: '#app',
data: { ments: ments },
methods: {
remove: function(index) { this.ments.splice(index, 1); app.$forceUpdate() },
},
})
</script>
The problem is that, if we remove a ment, the ponents are not refreshed accordingly. For example, we have 3 ments in the above implementation. if you remove ment 2, the preview of item 3 will still show the content of item 2. It is updated only if we press edit followed by cancel.
I've tried app.$forceUpdate(), but that didn't help.
2 Answers
Reset to default 7You just need to add key attribute in the v-for loop like following:
<li v-for="(ment, index) in ments" :key="ment">
See working fiddle: https://fiddle.jshell/mimani/zLrLvqke/
Vue tries to optimises rendering, by providing key attribute, it treats those as pletely different elements and re-renders those properly.
See the key documentation for more information.
try with:
Vue.ponent('ment', {
template:
`<div>
{{ ment }}
<button v-on:click="remove"> X </button>
</div>`,
props: ['ment', 'index'],
methods: {
remove: function() {
this.$emit('remove', this.index);
}
},
});
vm = new Vue({
el: '#app',
data: {
ments: ['a','b','c','d','e']
},
methods: {
remove: function(index) {
this.ments.splice(index, 1);
},
},
});<script src="https://cdnjs.cloudflare./ajax/libs/vue/2.1.8/vue.min.js"></script>
<div id="app">
<ol>
<li v-for="(ment, index) in ments">
<ment
v-bind:ment="ment"
v-bind:index="index"
v-on:remove="remove">
</ment>
</li>
</ol>
</div>