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[英]How to access firestore.Timestamp from Firebase Cloud Function
[英]Timestamp from firestore gets converted to a Map when using cloud function
所以我在雲 Firestore 中有一個Timestamp
。 我正在使用雲 function 從 firestore 檢索數據到 flutter。但是JSON
時間戳格式設置為 map,因此我無法將其用作時間戳。 如何將其再次轉換為時間戳?
這就是我將時間戳加載到 firestore 的方式。
var reference = Firestore.instance.collection('posts');
reference.add({
'postTitle': this.title,
'timestamp': DateTime.now(),
'likes': {},
'ownerId': userId,
})
要檢索數據,這是代碼:
factory Post.fromJSON(Map data){
return Post(
timestamp: data['timestamp'],
);
}
List<Post> _generateFeed(List<Map<String, dynamic>> feedData) {
List<Post> listOfPosts = [];
for (var postData in feedData) {
listOfPosts.add(Post.fromJSON(postData));
}
return listOfPosts;
}
但這會返回一個錯誤。
I/flutter (17271): The following assertion was thrown building FutureBuilder<DocumentSnapshot>(dirty, state:
I/flutter (17271): _FutureBuilderState<DocumentSnapshot>#1536b):
I/flutter (17271): type '_InternalLinkedHashMap<String, dynamic>' is not a subtype of type 'Timestamp'
這是我的雲 function。
getFeed.ts
import * as functions from 'firebase-functions';
import * as admin from 'firebase-admin';
export const getFeedModule = function(req, res){
const uid = String(req.query.uid);
async function compileFeedPost(){
const following = await getFollowing(uid, res)as any;
let listOfPosts = await getAllPosts(following, res);
listOfPosts = [].concat.apply([], listOfPosts);
res.send(listOfPosts);
}
compileFeedPost().then().catch();
}
async function getAllPosts(following, res) {
let listOfPosts = [];
for (let user in following){
listOfPosts.push( await getUserPosts(following[user], res));
}
return listOfPosts;
}
function getUserPosts(userId, res){
const posts = admin.firestore().collection("posts").where("ownerId", "==", userId).orderBy("timestamp")
return posts.get()
.then(function(querySnapshot){
let listOfPosts = [];
querySnapshot.forEach(function(doc){
listOfPosts.push(doc.data());
});
return listOfPosts;
})
}
function getFollowing(uid, res){
const doc = admin.firestore().doc(`user/${uid}`)
return doc.get().then(snapshot => {
const followings = snapshot.data().followings;
let following_list = [];
for (const following in followings){
if (followings[following] === true){
following_list.push(following);
}
}
return following_list;
}).catch(error => {
res.status(500).send(error)
})
}
雲 function index.ts
import * as functions from 'firebase-functions';
import * as admin from 'firebase-admin';
import { getFeedModule } from "./getFeed"
admin.initializeApp();
export const getFeed = functions.https.onRequest((req, res) => {
getFeedModule(req, res);
})
由此調用
_getFeed() async {
print("Starting getFeed");
FirebaseUser user = await FirebaseAuth.instance.currentUser();
SharedPreferences prefs = await SharedPreferences.getInstance();
String userId = user.uid;
var url =
'https://us-central1-jaluk-quiz.cloudfunctions.net/getFeed?uid=' + userId;
var httpClient = HttpClient();
List<QuizViewer>listOfPosts;
String result;
try {
var request = await httpClient.getUrl(Uri.parse(url));
var response = await request.close();
if (response.statusCode == HttpStatus.ok) {
String json = await response.transform(utf8.decoder).join();
prefs.setString("feed", json);
List<Map<String, dynamic>> data =
jsonDecode(json).cast<Map<String, dynamic>>();
listOfPosts = _generateFeed(data);
result = "Success in http request for feed";
} else {
result =
'Error getting a feed: Http status ${response.statusCode} | userId $userId';
}
} catch (exception) {
result = 'Failed invoking the getFeed function. Exception: $exception';
}
print(result);
setState(() {
feedData = listOfPosts;
});
}
實際上,在使用 Cloud 函數時,時間戳會作為普通 Map 返回。 但是如果您使用 Firebase SDK,它會返回Timestamp
對象。 我使用以下函數來處理這兩種情況:
DateTime dateTimeFromTimestamp(dynamic val) {
Timestamp timestamp;
if (val is Timestamp) {
timestamp = val;
} else if (val is Map) {
timestamp = Timestamp(val['_seconds'], val['_nanoseconds']);
}
if (timestamp != null) {
return timestamp.toDate();
} else {
print('Unable to parse Timestamp from $val');
return null;
}
}
與json_annotation
庫完美配合:
@JsonKey(
fromJson: dateTimeFromTimestamp,
toJson: dateTimeToTimestamp,
nullable: true)
final DateTime subscriptionExpiryDate;
如果您正在處理已序列化為具有秒和納秒組件的對象的 Timestamp,您可以使用這些組件創建一個具有new Timestamp(seconds, nanoseconds)
的新Timestamp對象。
您可以使用轉換來接收 DateTime,如下所示:
class TimestampConverter implements JsonConverter<DateTime, dynamic> {
const TimestampConverter();
@override
DateTime fromJson(dynamic data) {
Timestamp timestamp;
if (data is Timestamp) {
timestamp = data;
} else if (data is Map) {
timestamp = Timestamp(data['_seconds'], data['_nanoseconds']);
}
return timestamp?.toDate();
}
@override
Map<String, dynamic> toJson(DateTime dateTime) {
final timestamp = Timestamp.fromDate(dateTime);
return {
'_seconds': timestamp.seconds,
'_nanoseconds': timestamp.nanoseconds,
};
}
}
然后像這樣標記你的模型領域:
@TimestampConverter() DateTime createdAt
安德烈的回答非常好。 這是一個 JS/Typescript 改編,封裝在一個類中:
import app from 'firebase/app'
import 'firebase/firestore'
import TimeAgo from 'javascript-time-ago'
// Load locale-specific relative date/time formatting rules.
import en from 'javascript-time-ago/locale/en'
// Add locale-specific relative date/time formatting rules.
TimeAgo.addLocale(en)
// Adapted from Andrey Gordeev's answer at:
// https://stackoverflow.com/questions/56245156/timestamp-from-firestore-gets-converted-to-a-map-when-using-cloud-function
class MyClass {
timeAgo: TimeAgo
constructor() {
this.timeAgo = new TimeAgo('en-US')
}
getTimeText = (timeObject: any) => {
// Convert to time text once it's of type firestore.Timestamp
const getTextFromTimestamp = (timestamp: app.firestore.Timestamp) => {
return this.timeAgo.format(timestamp.toDate())
}
if (timeObject instanceof app.firestore.Timestamp) {
// Check if Timestamp (accessed from client SDK)
return getTextFromTimestamp(timeObject)
} else if (Object.prototype.toString.call(timeObject) === '[object Object]') {
// Check if it's a Map
const seconds = timeObject['_seconds']
const nanoseconds = timeObject['_nanoseconds']
if (seconds && nanoseconds) {
const timestamp = new app.firestore.Timestamp(seconds, nanoseconds)
return getTextFromTimestamp(timestamp)
}
}
console.log('Couldn\'t parse time', timeObject)
// Fallback
return 'some time ago'
}
}
DateTime? dateTimeFromTimeStamp(dynamic data) {
Timestamp? timestamp;
if (data is Timestamp) {
timestamp = data;
} else if (data is Map) {
timestamp = Timestamp(data['_seconds'], data['_nanoseconds']);
}
return timestamp?.toDate();
}
Map<String, dynamic>? dateTimeToTimeStamp(DateTime? dateTime) {
final timestamp = Timestamp.fromDate(dateTime ?? DateTime.now());
return {
'_seconds': timestamp.seconds,
'_nanoseconds': timestamp.nanoseconds,
};
}
然后像這樣使用它:
@JsonKey(
name: "creation_date",
fromJson: dateTimeFromTimeStamp,
toJson: dateTimeToTimeStamp)
DateTime? creationDate;
我通過將時間戳作為字符串發送來解決了我的問題。
"timestamp": DateTime.now().toString()
因為現在我的時間戳現在在字符串中,所以我從 JSON 中獲取確切的時間戳作為字符串。
現在我所做的是使用一個名為timeago
的 flutter 插件將其轉換為 time ago 格式,例如:“10 mins ago”
Text(timeago.format(DateTime.parse(timestamp)).toString);
我偶然發現了這個問題,因為我試圖弄清楚為什么我的雲函數沒有正確解析時間戳(並將其返回給調用者)。 實際上,在記錄時,我注意到我的日期字段顯示為Timestamp { _seconds: N, _nanoseconds: NN }
解決方案是在使用它之前簡單地將必要的字段轉換為 Timestamp 類。 否則會返回地圖:
const date = <field> as admin.firestore.Timestamp
print(expiryObj); //{_nanoseconds: 748000000, _seconds: 1612641862}
Timestamp tempstamp = Timestamp(expiryObj['_seconds'], expiryObj['_nanoseconds']);
DateTime expiryDateTime = tempstamp.toDate();
print(expiryDateTime); //2021-02-06 15:04:22.748
(導入導入'包:cloud_firestore/cloud_firestore.dart';)
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