Can't copy props to model data and render it in Vue 2 - vue.js

Question

I'm having this problem that looks a lot like a bug to me and I can't figure out how to solve it.
I created a generic list component and I tell it what child component it should insert in each item and what are the data it should pass to the child component. I'm passing everything as props along with the list (array) itself.
The problem is that I can't mutate the list props. So I try to copy it to model attribute. Otherwise I get this error:
Avoid mutating a prop directly since the value will be overwritten
whenever the parent component re-renders.....
And I can't just make it work in any of the lifecycle events. When I save the file and the hot-reloading reloads the page, the list is there, rendered, full of items. When I press F5 to manually reload the page, it is no more. Everything seems to be alright with code though
So in the parent component I'm doing this:
<List ref="link_list"
:list="this.foo.links" //this is array
:child="'LinkFormItem'" //this is the name of the child component
:section_name="'Links'"
:defaults="{content: '', type: 'facebook'}" />
In the List component I get this:
Template
<li class="" v-for="item in datalist">
<component :is="child" :item="item" ></component>
<button v-on:click='remove(index++)' type="button" name="button" class='red button postfix small'>Remove</button>
</li>
Script
<script>
import Child1 from './Child1'
import Child2 from './Child2'
export default {
name: 'search',
props: ['child', 'list', 'defaults','section_name'], //it is received as 'list'
components: {
Child1, Child2
},
data () {
return {
index: 0,
datalist: [] //i'm trying to copy 'list' to 'datalist'
}
},
beforeMount: function () {
// i'm copying it
for(var k in this.list){
this.datalist.push(this.list[k])
}
},
methods: {
//and here I should change it the way I want
add: function () {
this.datalist.push(this.defaults)
},
getList () {
return this.datalist;
},
remove(index){
var datalist = [];
for(var k in this.datalist){
if(k != index) datalist.push(this.datalist[k]);
}
this.datalist = datalist;
}
}
}
</script>
I don't see any problems with my Script. What is going on??
#edit
Ok, some console.log later I found out what the problem seems to be. The HTTP Request is really taking much longer than the mounting of the component to happen. But when it happens, it is not triggering the update in the list component. Nothing is re-rendered and the list is empty.
Workaround
well I realised the problem was related to propagation. I made a few changes in the code to asure the parent component was updating and changing the model value. but the child component (the list component) was not receiving it.
then I gave up trying to understand why and did the following:
1- used the ref in the child component to force an update in the child component with $forceUpdate and then I was assigning the props to the model in the beforeUpdate event. It was causing an error: an re-rendering loop. The update caused a new update and so on. We could just use a flag to stop it.
2- Instead I just called a child method directly:
this.$refs.link_list.updateList(data.links);
I hate this approach because I think it's way too explicit. But it did the job. Then in the child component a new method:
updateList(list){
this.datalist = list;
}
3- The other possibility that passed through my mind was emitting an event. But I didn't try, too complicated

Answer 1

You can simply do like as follows
data () {
return {
index: 0,
datalist: this.list // to copy props to internal component data
}
},
Once you done about you need to apply data manipulation opertions on new this.datalist , not on this.list

Answer 2

If you don't want to mutate the original list array you can do this:
data () {
return {
index: 0,
datalist: Object.assign({}, this.list)
}
}
I think this will help you