Vue Component props value is does not seem on template - vue.js

Question

Everything is fine in my main.js
import User from './components/User.vue'
new Vue({
el: '#user',
render: h => h(User),
data() {
return {
groups: []
}
},
mounted() {
this.getGroups();
},
methods: {
getGroups: function () {
axios.get('http://vagrant.dev/groups')
.then(response => this.groups = response.data)
.catch(error => console.log(error));
}
}
});
User.vue
<template>
<div id="user">
{{groups}} <!-- must be printed but it doesn't seem -->
</div>
</template>
<script>
export default {
name: 'user',
props: ['groups']
}
</script>
and index.html
<div id="user">
<user :groups="groups"></user>
</div>
Where is the mistake?
I do not get any errors, but I didn't understand why the value was not printed on the screen

Answer 1

Seems like you are putting 2 Vue instances on the same template since in your main file you are defining the template as el: "#user" which is already controlled by User.vue.
In you index.html add a div with id="app" and in main.js set el: "#app"

Answer 2

Your main.js and index.html shouldn't mix template in HTML and render function. So your main.js should be:
```new Vue({
el: '#user',
components: { User },
data() {
return {
groups: []
}
},
...```
You shouldn't directly reassign data value because Vue cannot detect property additions and rerender view. You should do it via Vue.set or this.$set like this:
this.$set(this, 'groups', response.data)
You can read more about how vue reactive in https://v2.vuejs.org/v2/guide/reactivity.html and Vue.set API: https://v2.vuejs.org/v2/api/#Vue-set