Firebase array-contains - 搜索值而不是键

Question

如何查询具有数字键集的数组中的值？

例如，这个查询不起作用，因为我相信它正在查看索引而不是值：

var db = firebase.firestore();
var users = db.collection("Users");
var currentUser = firebase.auth().currentUser;
var result = users.where('liked', 'array-contains', currentUser.uid);
if (result.length > 0) {
  return 'You have a match!';
} else {
  return 'No matches';
}

Answer 1

正如 Stratubas 评论的那样，问题出在这段代码中：

var result = users.where('liked', 'array-contains', currentUser.uid);

此代码构造查询，但尚未执行查询。所以 result 是 Query object. To execute the query, and get the results from the server, you call get() on the query, which then returns a Promise<QuerySnapshot>. Once the promise results, you can handle the results in the QuerySnapshot object.

var query = users.where('liked', 'array-contains', currentUser.uid);
query.get().then(function(querySnapshot) {
  if (querySnapshot.size > 0) {
    console.log('You have a match!');
  } else {
    console.log('No matches');
  }
});

更现代的JavaScript，上面也可以写成：

let query = users.where('liked', 'array-contains', currentUser.uid);
let querySnapshot = await query.get()
if (querySnapshot.size > 0) {
  console.log('You have a match!');
} else {
  console.log('No matches');
}