Vuex getter not updating

Question

I have the below getter:

    withEarmarks: state => {         var count = 0;         for (let l of state.laptops) {             if (l.earmarks.length > 0) {                 count++;             }         }       return count;     } 

And in a component, this computed property derived from that getter:

        withEarmarks() { return this.$store.getters.withEarmarks; }, 

The value returned is correct, until I change an element within the laptops array, and then the getter doesn't update.

Answer 1

In your case state.laptops.earmarks is an array, and you are manipulating it by its array index state.laptops[index]. Vue is unable to react to mutations on state arrays (by index). The documentation provides 2 workarounds for this:

// 1. use purpose built vue method: Vue.set(state.laptops, index, laptop)    // 2. splice the value in at an index: state.laptops.splice(index, 1, laptop) 

Although it is documented, I'm thinking a giant neon glowing sign on that page that says "You will waste hours of productivity if you don't know this" would be a nice addition.

You can read more about this "caveat" here: https://vuejs.org/v2/guide/list.html#Caveats