Vue.js list binding doesn't work - asp.net

Question

Sorry for my english.
Data binding doesn't work.
All data correctly serializing and displayed, but if i try to change some value - nothing happens.
Klik() method working correctly, conditions works correctly.
Please, help.
HTML code
<div id="app">
<div class="areaInfo " v-for="area in mainObjects" v-on:click="klik(area)">
<div class="trDiv areaData">
<div class="tdDiv" v-for="(prop, key) in area" v-if="key != 'ChildData'">
{{key}}
<template v-if="key.includes('Start') || key.includes('End') ">
{{ ConvertJsonDateString(prop) }}
</template>
<template v-else-if="!key.includes('Id')">
{{ prop }}
</template>
</div>
<div class="tdDiv" > {{area.childSeen}}</div>
</div>
</div>
</div>
Script:
var mainObjects = #(Html.Raw(result.Content));
for (var i = 0; i < mainObjects.length; i++) {
mainObjects[i].childSeen = false;
for (var j = 0; j < mainObjects[i].ChildData.length; j++) {
mainObjects[i].ChildData[j].childSeen = false;
}
}
console.log(mainObjects);
var app = new Vue({
el: "#app",
data: mainObjects,
methods: {
klik: function (region) {
console.log(region.childSeen)
if (region.childSeen == false) {
console.log('wasFalse');
return region.childSeen = true;
}
return region.childSeen = false;
}
},
});
Model example:
public class Test
{
public string FirstName {get;set;}
public string LastName {get;set;}
public List<Rebenok> ChildData {get;set;}
}
public class Rebenok
{
public string FirstName {get;set;}
public string LastName {get;set;}
public List<Diagnosis> Diagnoses {get;set;}
}
public class Diagnosis
{
public string Name {get;set;}
public string Description {get;set;}
}

Answer 1

mainObjects reference is not changed. You need to deep copy to make Vue reactive
<div id="app">
<div class="areaInfo " v-for="(area, index) in mainObjects" v-on:click="klik(index)">
<div class="trDiv areaData">
<div class="tdDiv" v-for="(prop, key) in area" v-if="key != 'ChildData'">
{{key}}
<template v-if="key.includes('Start') || key.includes('End') ">
{{ ConvertJsonDateString(prop) }}
</template>
<template v-else-if="!key.includes('Id')">
{{ prop }}
</template>
</div>
<div class="tdDiv" > {{area.childSeen}}</div>
</div>
</div>
</div>
var app = new Vue({
el: "#app",
data () {
return {
mainObjects
}
},
methods: {
klik: function (index) {
const mainObjects = JSON.parse(JSON.stringify(mainObjects)) // deep copy
const region = mainObjects[index]
console.log(region.childSeen)
if (region.childSeen == false) {
console.log('wasFalse');
region.childSeen = true;
}
region.childSeen = false;
this.mainObjects = mainObjects // assign again
}
},
});