Question

我目前正在使用Firebase和Firebase功能。我正在尝试在集合（集合：“项目”）中获取文档。我尝试进行一次GET，但是我只有200个空的车身。

fun changeUserAccount(
        userName: String,
        password: String,
        confirmPassword: String,
        realName: String,
        accountEmail: String,
        applicationContext: Context
    ) {

        //You can pass n number of strings.
        val isAllStringsValid = StringUtils.isAllValid(userName,password,confirmPassword,realName,accountEmail)

       //this returns true
       StringUtils.isAllValid("hi","how","are","you","?")


       //this returns false
       StringUtils.isAllValid("","how","are","you","?")


       //this returns false
       StringUtils.isAllValid(null,"how","are","you","?")


       //this returns false
       StringUtils.isAllValid("","how","are","you","?")
    }

Firebase collection screenshot

有趣的是，当我查询特定项目时，我得到了包含文档数据的JSON正文：

app.get('/api/read/items', (req, res) => {
(async () => {
    try {
        let response = [];
        let itemRefs = db.collection('items').get().then(snapshot => {
            snapshot.forEach((item) => {
                response.push(item.data());
            });
            console.log(response);
        });
        return res.send(response);
    } catch (error) {
        debug.log(error);
        return res.status(500).send(error);
    }
})();
});

期待看到我犯了什么错误：）！

谢谢您的帮助！

Answer 1

数据从Firestore异步加载。到您的res.send(response)执行时，snapshot.forEach(...)尚未运行。

解决方案是从最内层的回调中将响应发送到客户端：

app.get('/api/read/items', (req, res) => {
(async () => {
    try {
        let response = [];
        return db.collection('items').get().then(snapshot => {
            snapshot.forEach((item) => {
                response.push(item.data());
            });
            console.log(response);
            return res.send(response);
        });
    } catch (error) {
        debug.log(error);
        return res.status(500).send(error);
    }
})();
});

或者，您可以像在第二个片段中一样使用await：

app.get('/api/read/items', (req, res) => {
(async () => {
    try {
        let response = [];
        let snapshot = await snapshot db.collection('items').get();
        snapshot.forEach((item) => {
            response.push(item.data());
        });
        return res.send(response);
    } catch (error) {
        return res.status(500).send(error);
    }
})();
});

您可以进一步简化以下内容：

app.get('/api/read/items', (req, res) => {
(async () => {
    try {
        let snapshot = await snapshot db.collection('items').get();
        let response = snapshot.documents.map((item) => item.data());
        return res.send(response);
    } catch (error) {
        return res.status(500).send(error);
    }
})();
});

Answer 2

我想我已经找到了问题的根本原因，由于我对节点/表达式的了解不足，所以我无法解释为什么。在测试时，我有index.js文件，其中包含：

public class MoviePostersListViewModel extends ViewModel {

    MovieRepository movieRepository;

    public MoviePostersListViewModel() {
        movieRepository = MovieRepository.getInstance();
    }

    public LiveData<List<Movie>> getMovies() {
        return movieRepository.getMovies();
    }

    public void retrieveMoviesApi(String query, int pageNumber){
        movieRepository.retrieveMoviesApi(query, pageNumber);
    }
}

尝试对read / geoFencedUsers进行GET调用会返回200，但响应为空。更改完我的index.js并在上面移动了get方法后，解决了使所有3个调用都工作以返回正确的数据响应的问题。

const serviceAccount = require("./permissions.json");
const functions = require('firebase-functions');
const admin = require('firebase-admin');
const express = require('express');
const cors = require('cors');
const app = express();

const db = admin.firestore();
......
app.get('/api/read/items', (req, res) => {
    (async () => {
        try {
            let response = [];
            return db.collection('items').get().then(snapshot => {
                snapshot.forEach((item) => {
                    response.push(item.data());
                });
                console.log(response);
                return res.send(response);
            });
        } catch (error) {
            console.log(error);
            return res.status(500).send(error);
        }
    })();
});

// read item
app.get('/api/read/:item_id', (req, res) => {
    (async () => {
        try {
            const document = db.collection('items').doc(req.params.item_id);
            let item = await document.get();
            let response = item.data();
            return res.status(200).send(response);
        } catch (error) {
            console.log(error);
            return res.status(500).send(error);
        }
    })();
});


app.get('/api/read/geoFencedUsers', (req, res) => {
    (async () => {
        try {
            let response = [];
            return db.collection('geoFencedUsers').get().then(snapshot => {
                snapshot.forEach((geoFencedUser) => {
                    response.push(geoFencedUser.data());
                });
                return res.status(200).send(response);
            })
        } catch (error) {
            return res.status(500).send(error);
        }
    })();
});

Firebase响应返回200，但数组为空

2 个答案: