Using conditional class with store getters: not updating class - vue.js

Question

I have a div with a conditional class that works well when the app is loaded, but it's not updated when the store data change.
The code in my vue component looks like this
<span class="week-day"
v-bind:class="{ complete: isDayComplete(day) }"
v-for="day in daysInWeek"
v-bind:data-day="day"
> </span>
And I have ...mapGetters(['isDayComplete']) in my computed object.
The getter looks like this
isDayComplete(state) {
return (day) => {
console.log(`called isDayComplete(${day})`)
const formattedDay = moment(day, 'DD/MM/YYYY').format('YYYY-MM-DD');
if (state.daysData[formattedDay]) {
if (state.daysData[formattedDay].meals.length > 0) {
console.log(`day ${day} is complete`);
return true;
} else {
console.log(`day ${day} is NOT complete`);
return false;
}
} else {
console.log(`no data for day ${day}`);
return false;
}
}
},
I update my meals data in a mutation
updateMeals(state, meals) {
_.forEach(meals, (meal) => {
state.daysData[meal.day].meals.push(meal);
});
}
And I have an action that commits that mutation
loadMeals({ state, commit }) {
return new Promise((resolve, reject) => {
get.meals.from.api()
.then((response) => {
commit('initDaysData');
commit('updateMeals', response.data.data);
return resolve();
})
.catch(reject);
});
}
So whenever I call loadMeals the class is not updated if one day changes its status (complete/not-complete). If I reload the page, the class is set correctly.
What am I doing wrong? Thanks!

Answer 1

It's a common reactivity problem. You can make deep copy (use JSON.parse(JSON.stringify())) to make data reactive:
updateMeals(state, meals) {
_.forEach(meals, (meal) => {
state.daysData[meal.day].meals.push(meal);
});
state.daysData = JSON.parse(JSON.stringify(state.daysData))
}

Answer 2

#ittus answer was correct. I found another way to achieve this that maybe could
help someone else.
add another mutation on the store
updateCompletedDays(state) {
const newState = [];
_.forEach(state.daysData, (currentDayData, currentDay) => {
if (currentDayData.meals.length > 0) {
newState.push(currentDay);
}
});
state.completedDays = newState;
},
commit this mutation after meals are updated
change isDayComplete getter to
isDayComplete(state) {
const formattedDay = moment(day, 'DD/MM/YYYY').format('YYYY-MM-DD');
return state.completedDays.indexOf(formattedDay) !== -1;
}
Basically when using reactivity going deep into arrays/object will not work, better have arrays of aggregated data (check also Vue.set api)