1// Copyright 2021 Google LLC
2//
3// Licensed under the Apache License, Version 2.0 (the "License");
4// you may not use this file except in compliance with the License.
5// You may obtain a copy of the License at
6//
7//      http://www.apache.org/licenses/LICENSE-2.0
8//
9// Unless required by applicable law or agreed to in writing, software
10// distributed under the License is distributed on an "AS IS" BASIS,
11// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
12// See the License for the specific language governing permissions and
13// limitations under the License.
14
15// [START firestore_generated_firestore_Query_Snapshots]
16
17package main
18
19import (
20	"context"
21	"fmt"
22
23	"cloud.google.com/go/firestore"
24	"google.golang.org/api/iterator"
25)
26
27func main() {
28	ctx := context.Background()
29	client, err := firestore.NewClient(ctx, "project-id")
30	if err != nil {
31		// TODO: Handle error.
32	}
33	defer client.Close()
34
35	q := client.Collection("States").
36		Where("pop", ">", 10).
37		OrderBy("pop", firestore.Desc).
38		Limit(10)
39	qsnapIter := q.Snapshots(ctx)
40	// Listen forever for changes to the query's results.
41	for {
42		qsnap, err := qsnapIter.Next()
43		if err == iterator.Done {
44			break
45		}
46		if err != nil {
47			// TODO: Handle error.
48		}
49		fmt.Printf("At %s there were %d results.\n", qsnap.ReadTime, qsnap.Size)
50		_ = qsnap.Documents // TODO: Iterate over the results if desired.
51		_ = qsnap.Changes   // TODO: Use the list of incremental changes if desired.
52	}
53}
54
55// [END firestore_generated_firestore_Query_Snapshots]
56