如何通过 Mongoose 从 Mongodb 中的嵌套文档中获取 Nodejs 中的数组？
2019-06-12
115
我试图从 mongoose Model 对象中以数组的形式获取电子邮件。因此，我可以在查询中循环数组并按时间排序获取其他用户的所有帖子，我是 Node JS 和 Javascript 的新手。以下是代码和架构：
这是架构：
var userSchema = mongoose.Schema({
_id: {type: String, default: mongoose.Types.ObjectId()},
email: {type: String},
userProfile: userProfileSchema
});
var userProfileSchema = mongoose.Schema({
friendNetwork: [{
"email": String,
"chatId": String,
"name": String
}],
posts: [{
"_id" : {type: String, default: mongoose.Types.ObjectId()},
"postCreator" : String,
"isShared" : {type: String, default: ""},
"timestamp": String,
"text": String,
"images": [String],
"videos": [String],
"likes": [String],
"comments": [{
"status": {type: Boolean, default: true},
"commentId" : {type: String, default: mongoose.Types.ObjectId()},
"commentCreator": String,
"comment": String,
"timestamp": String,
}],
"shares": [String],
"isDelete" : {Boolean, default: false},
"isOnlyMe": {Boolean, default: false}
}],
isDelete: {type: Boolean, default: false}
});
我尝试了 map 函数，但出现错误“TypeError：无法读取 null 的属性‘map’”。
这是代码：
app.get('/newsfeed/getfeed', (req, res, err) => {
try
{
// active user email in query
userModel.findOne({email: req.query.email}, (user) => {
// array to get email of all active user's friends
let userEmails = user.map(user => user.userProfile.friendNetwork.email);
//traverse through all friends and get their respective posts shared with friends
userModel.find({email : { $in: userEmails }}, (err,users) => {
users.userProfile.posts.find({ isOnlyMe: false }, (posts) => {
// Mongo Atlas already ordered by timestamp, no need to add further sorting
res.send(posts);
});
});
});
}
catch
{
console.log(err);
logger(err, "Getting newsfeed of main page failed.");
}
});
2个回答
回调中提供的第一个参数通常是错误值。您应该将代码行更改为：
userModel.findOne({email: req.query.email}, (err, user) => {
您可以在此处查看该函数的文档： https://mongoosejs.com/docs/api.html#model_Model.findOne
MattB
2019-06-12
找到了解决方案，显然我没有将数组传递给 map 函数。map 函数仅接受并通过数组工作。
app.get('/newsfeed/getfeed', (req, res, err) => {
try
{
// active user email in query
userModel.findOne({email: req.query.email}, (err,user) => {
// array to get email of all active user's friends
***let userEmails = user.userProfile.friendNetwork.map((friend) =>{***
return friend.email;
});
userEmails.push(req.query.email);
console.log(userEmails);
//traverse through all friends and get their respective posts shared with friends
userModel.find({ email: { $in: userEmails }}, (err,users) => {
console.log(users);
users.userProfile.posts.find({ isOnlyMe: false }, (err,posts) => {
// Mongo Atlas already ordered by timestamp, no need to add further sorting
res.send(posts);
});
});
});
}
catch
{
console.log(err);
logger(err, "Getting newsfeed of main page failed.");
}
});
Shahzar Khalid
2019-06-12