node.js Mongoose Mongodb 查询对象数组
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Mongoose Mongodb querying an array of objects
提问by Paulie
I am struggling to get what I expect to see when querying an array using Mongoose. A user can have many rooms associated with his/her account. The room objects are stored in an array attached to the user within the collection. There is only one collection called users.
在使用 Mongoose 查询数组时，我正在努力获得我期望看到的内容。一个用户可以有许多与他/她的帐户相关联的房间。房间对象存储在集合中附加到用户的数组中。只有一个集合称为用户。
Consider the following two Schemas for user and room:
考虑以下两个用户和房间模式：
USER SCHEMA
用户架构
var userSchema = mongoose.Schema({
local : {
username : String,
email : String,
password : String,
rooms : {type:Array, default: []}
}
});
ROOM SCHEMA
房间结构
var roomSchema = mongoose.Schema({
name: String
});
This is the query I have tried:
这是我试过的查询：
var User = require('../models/user');
User.find({ 'rooms.name' : req.body.username },
{ rooms:
{ $elemMatch :
{
name: req.body.username
}
}
}, function (err, user) {
if (err){
return done(err);
}
console.log("user:::", user);
if (user) {
console.log("ROOM NAME FOUND");
req.roomNameAlreadyInUse = true;
next();
} else {
req.roomNameAlreadyInUse = false;
console.log("ROOM NAME NOT FOUND");
next();
}
});
The problem is this query seems to always return an empty array even if it should contiain something or if it should return nothing. So how would I search through all users room arrays to see if the room name already exists?
问题是这个查询似乎总是返回一个空数组，即使它应该包含某些东西或者它不应该返回任何东西。那么我将如何搜索所有用户房间数组以查看房间名称是否已存在？
I have also tried the following to queries but neither are successful:
我还尝试了以下查询，但都没有成功：
User.find({local: {rooms: {$elemMatch: {name: req.body.username}}}}, function (err, user) {
}
User.find({'local.rooms': {$elemMatch: {name: req.body.username}}}, function (err, user) {
}
I should also point out that the database is populated as I can see the array (which has 1 element created on user account creation) in robomongo.
我还应该指出，数据库已填充，因为我可以在 robomongo 中看到数组（在创建用户帐户时创建了 1 个元素）。
Sample data from console output to show database is being populated (including user.rooms array):
正在填充来自控制台输出的示例数据以显示数据库（包括 user.rooms 数组）：
db.users.find() { "_id" : ObjectId("533c4db2b2c311a81be8a256"), "local" : { "password" : "$2a$08$0yQQJ2y0726kZtkWY5mAPOgZhacOmZn0Fd8DlausiuMB XE4ZblTXS", "username" : "paul", "email" : "test", "rooms" : [ { "name" : "paul", "id" : ObjectId("533c4db2b2c311a81be8a2 57") } ], "status" : "active" }, "_v" : 0 } { "_id" : ObjectId("533c4ddab2c311a81be8a258"), "local" : { "password" : "$2a$08$dC3CbDTkG5ozECDTu/IicO3Az0WdkzlGh2xDcb8j1CF/ FQhe5guZq", "username" : "john", "email" : "test2", "rooms" : [ { "name" : "john", "id" : ObjectId("533c4ddab2c311a81be8a 259") } ], "status" : "active" }, "_v" : 0 }
db.users.find() { "_id" : ObjectId("533c4db2b2c311a81be8a256"), "local" : { "password" : "$2a$08$0yQQJ2y0726kZtkWY5mAPOgZhacOmZn0Fd8DlausiuMB","Xmailzd8DlausiuMBe",测试”，“房间”：[{“名称”：“保罗”，“ id”：ObjectId（“533c4db2b2c311a81be8a2 57”）}]，“状态”：“活动”}，“_v”：0}{“ _id” : ObjectId("533c4ddab2c311a81be8a258"), "local" : { "password" : "$2a$08$dC3CbDTkG5ozECDTu/IicO3Az0WdkzlGh2xDcb8j1CF/ FQhe5guZq", "", "user {“姓名”：“约翰”，“id”：ObjectId（“533c4ddab2c311a81be8a 259”）}]，“状态”：“活动”}，“_v”：0}
回答by Paulie
I changed it to use findOne instead of find and it works now. I am not too sure why this should make a difference. This is the findOne function I used:
我将其更改为使用 findOne 而不是 find 并且现在可以使用了。我不太确定为什么这会有所作为。这是我使用的 findOne 函数：
User.findOne({'local.rooms': {$elemMatch: {name: req.body.username}}}, function (err, user) {
if (err){
return done(err);
}
if (user) {
console.log("ROOM NAME FOUND");
req.roomNameAlreadyInUse = true;
next();
} else {
req.roomNameAlreadyInUse = false;
console.log("ROOM NAME NOT FOUND");
next();
}
});
回答by Binu
findOnereturns a single document, where findreturns a cursor. Once you go through the cursor of find, you are at the end, and there are no more documents.
findOne返回单个文档，其中find返回一个游标。一旦你通过 find 的光标，你就到了最后，而且没有更多的文件。
User.findOne({'local.rooms': {$elemMatch: {name: req.body.username}}}, (err,UserInfo) => {
if (err){
return res.status(400).json({Error:"Something went wrong please try again"})
}
if (UserInfo) {
console.log("ROOM NAME FOUND");
req.roomNameAlreadyInUse = true;
res.json({msg:"Room name found.",userData:UserInfo})
} else {
req.roomNameAlreadyInUse = false;
console.log("ROOM NAME NOT FOUND");
res.json({msg:"Room name not found."})
}
});
