按对象查询Firestore集合

Question

I create a collection called "books", in it I made an object (aka. dict) called "users". That object looks like this:

users: {
    5PPCTcdHOtdYjGFr7gbCEsiMaWG3: firebase.firestore.FieldValue.serverTimestamp()
}

Now I want to query all books that belong to a certain user. I tried this:

this.db
  .collection('books')
  .where(`users.${this.state.currentUser.uid}`, '>', 0)
  .onSnapshot(querySnapshot => {
      ...

I never get any documents returned. I'm sure the there is something it should match.

To check my sanity, if I remove the where(...) part, I do get documents. Just that I get documents for all users.

I console logged that string in the .where() and it looks right.

Answer 1

I can't get this to work with .where() either, but it seems to work using .orderBy() , replacing:

.where(`users.${this.state.currentUser.uid}`, '>', 0)

with

.orderBy(`users.${this.state.currentUser.uid}`)

Answer 2

You're query is wrong because you are comparing a date object with a number, therefore two different things. You can check it by running these two lines of code below.

  console.log(typeof(firebase.firestore.FieldValue.serverTimestamp()))
  console.log(typeof(0))

So you have two options:

1 - You can compare date objects with data objects like below.

this.db
  .collection('books')
  .where(`users.${this.state.currentUser.uid}`, '>', new Date(0))
  .onSnapshot(querySnapshot => {
      ...

2 - Or you can save your date in milliseconds and compare it with a number.

users: {
    5PPCTcdHOtdYjGFr7gbCEsiMaWG3: new Date().getTime();
}

 this.db
      .collection('books')
      .where(`users.${this.state.currentUser.uid}`, '>', 0)
      .onSnapshot(querySnapshot => {
          ...