TypeError: Cannot set property 'words' of undefined - firebase

Question

I have this action in my vuex store:
loadExercises ({commit}) {
commit('setLoading', true)
const db = firebase.firestore()
db.collection('exercises').get()
.then(querySnapshot => {
const exercises = []
querySnapshot.forEach((doc) => {
exercises.push({
title: doc.data().title,
language: doc.data().language,
translated: doc.data().translated,
lastOpen: doc.data().lastOpen,
dueDate: doc.data().dueDate,
uid: doc.data().uid,
userId: doc.data().userId,
words: [{ word: '', uid: '', translation: '' }]
})
db.collection('exercises').doc(doc.data().uid).collection('words').get()
.then(words => {
const wordsArray = []
words.forEach(word => {
wordsArray.push(word.data())
})
let exercise = this.getters.loadedExercise(doc.data().uid)
exercise.words = wordsArray
})
.catch(error => {
commit('setLoading', false)
console.log(error)
})
})
commit('setLoading', false)
commit('setLoadedExercises', exercises)
})
.catch(error => {
commit('setLoading', false)
console.log(error)
})
}
It is supposed to fetch exercises from a firebase cloudstore db. It works on some routes but not all.
When using these two getters it works:
loadedExercises (state) {
return state.loadedExercises
},
loadedExercise (state) {
return (exerciseId) => {
return state.loadedExercises.find(exercise => {
return exercise.uid === exerciseId
})
}
}
But when I use these getters:
upcomingExercises (state, getters) {
return getters.loadedExercises.filter(exercise => {
return exercise.dueDate > 0
})
},
latestExercises (state, getters) {
return getters.loadedExercises.splice(0, 5)
},
it does not work I just get "TypeError: Cannot set property 'words' of undefined". What is it that I do wrong?

Answer 1

It looks to me like you aren't returning the values back to the function.
Try replacing
db.collection('exercises').get()
with
return db.collection('exercises').get()
and
db.collection('exercises').doc(doc.data().uid).collection('words').get()
with
return db.collection('exercises').doc(doc.data().uid).collection('words').get()