javascript - 从 firebase 调用集合是空的

Question

我正在尝试从名为“通知”的 firebase 集合中获取一些信息，以便在用户的问题得到解答时通知用户。问题是当我调用集合时，它会以空数组的形式返回。

这是我从 firebase 调用信息的代码。我使用控制台日志在第 34 行调用数据库：

import React, { useEffect, useState } from "react";
import { makeStyles } from "@material-ui/core/styles";
import Popper from "@material-ui/core/Popper";
import NotificationsIcon from "@material-ui/icons/Notifications";
import "../Style/Header.css";
import db from "../firebase";

const useStyles = makeStyles((theme) => ({
    paper: {
        border: "1px solid",
        padding: theme.spacing(1),
        backgroundColor: theme.palette.background.paper,
        zIndex: "10",
    },
}));

export default function SimplePopper() {
    const classes = useStyles();
    const [anchorEl, setAnchorEl] = React.useState(null);
    const [notifications, setNotifications] = useState([]);

    const handleClick = (event) => {
        setAnchorEl(anchorEl ? null : event.currentTarget);
    };

    const open = Boolean(anchorEl);
    const id = open ? "simple-popper" : undefined;

    useEffect(() => {
        db.collection("notifications")
            // .where("user.askerUserId", "==", auth.currentUser.uid)
            .orderBy("timestamp", "desc")
            .onSnapshot((snapshot) => {
                console.log(snapshot.docs);
                setNotifications(
                    snapshot.docs.map((doc) => ({
                        id: doc.id,
                        content: doc.data().content,
                    }))
                );
            });
    }, []);

    return (
        <div className="header__icon">
            <NotificationsIcon
                aria-describedby={id}
                type="button"
                onClick={handleClick}
            />
            <Popper id={id} open={open} anchorEl={anchorEl} style={{ zIndex: 100 }}>
                <div className={classes.paper}>
                    <ul className="notifications">
                        {notifications.map((notification) => (
                            <li key={notification.id}>{notification.content}</li>
                        ))}
                    </ul>
                </div>
            </Popper>
        </div>
    );
}

标签： javascriptreactjsgoogle-cloud-firestore

Answer 1

LeadDreamer 指出了这一点。问题是当我将文档发布到firestore时我没有正确标记“时间戳”字段，我认为firebase会自动添加它们。相反，我将其列为“时间”。

以下是我更改的 firebase 函数 index.js 文件中的代码，使其工作：

exports.answerCreated = functions.firestore
  .document("questions/{questionsId}/answer/{answerId}")
  .onCreate(async (doc) => {
    const project = doc.data();
    const { displayName, uid } = project.user;
    const questionSnapshot = await admin
      .firestore()
      .collection("questions")
      .doc(project.questionId)
      .get();
    const question = questionSnapshot.data();
    if (question) {
      const { user } = question;
      const notification = {
        content: "Added an answer",
        user: {
          askerUserId: user.uid,
          displayName,
          uid,
        },
        timestamp: admin.firestore.FieldValue.serverTimestamp(),
      };

      return createNotification(notification);
    }
  });