猫鼬查询:在数组中查找元素 [英] Mongoose Query: Find an element inside an array
问题描述
猫鼬/蒙古菜鸟在这里:
Mongoose/Mongo noob here:
我的数据
这是我的简化数据，每个用户都有自己的文档
Here is my simplified data, each user has his own document
{ "__v" : 1,
"_id" : ObjectId( "53440e94c02b3cae81eb0065" ),
"email" : "test@test.com",
"firstName" : "testFirstName",
"inventories" : [
{ "_id" : "active",
"tags" : [
"inventory",
"active",
"vehicles" ],
"title" : "activeInventory",
"vehicles" : [
{ "_id" : ObjectId( "53440e94c02b3cae81eb0069" ),
"tags" : [
"vehicle" ],
"details" : [
{ "_id" : ObjectId( "53440e94c02b3cae81eb0066" ),
"year" : 2007,
"transmission" : "Manual",
"price" : 1000,
"model" : "Firecar",
"mileageReading" : 50000,
"make" : "Bentley",
"interiorColor" : "blue",
"history" : "CarProof",
"exteriorColor" : "blue",
"driveTrain" : "SWD",
"description" : "test vehicle",
"cylinders" : 4,
"mileageType" : "kms" } ] } ] },
{ "title" : "soldInventory",
"_id" : "sold",
"vehicles" : [],
"tags" : [
"inventory",
"sold",
"vehicles" ] },
{ "title" : "deletedInventory",
"_id" : "deleted",
"vehicles" : [],
"tags" : [
"inventory",
"sold",
"vehicles" ] } ] }
如您所见，每个用户都有一个inventories属性，该属性是一个包含3个清单(activeInventory，soldInventory和DeletedInventory)的数组.
As you can see, each user has an inventories property that is an array that contains 3 inventories (activeInventory, soldInventory and deletedInventory)
我的查询
给用户的电子邮件中有一个车辆ID，我希望我的查询通过查找用户的activeInventory并只返回与该ID相匹配的车辆.这是我到目前为止的内容:
Given an user's email a a vehicle ID, i would like my query to go through find the user's activeInventory and return just the vehicle that matches the ID. Here is what I have so far:
user = api.mongodb.userModel;
ObjectId = require('mongoose').Types.ObjectId;
return user
.findOne({email : params.username})
.select('inventories')
.find({'title': 'activeInventory'})
//also tried
//.where('title')
//.equals('activeInventory')
.exec(function(err, result){
console.log(err);
console.log(result);
});
这样，结果以空数组的形式出现.我也尝试过.find('inventories.title': 'activeInventory')，它奇怪地返回了整个库存数组.如果可能的话，我希望保持链接查询格式的可读性.
With this, result comes out as an empty array. I've also tried .find('inventories.title': 'activeInventory') which strangely returns the entire inventories array. If possible, I'd like to keep the chaining query format as I find it much more readable.
我的理想查询
return user
.findOne({email : params.username})
.select('inventories')
.where('title')
.equals('activeInventory')
.select('vehicles')
.id(vehicleID)
.exec(cb)
显然它不起作用，但可以使您了解我要做什么.
Obviously it does not work but it can give you an idea what I'm trying to do.
推荐答案
使用 $ 位置运算符，您可以获得结果.但是，如果vehicles数组中有多个元素，则所有这些元素都将返回结果中，因为您只能在投影中使用一个位置运算符，并且要使用2个数组(一个在另一个数组中).
Using the $ positional operator, you can get the results. However, if you have multiple elements in the vehicles array all of them will be returned in the result, as you can only use one positional operator in the projection and you are working with 2 arrays (one inside another).
我建议您看看 aggregation framework ，因为这样会得到更大的灵活性.这是在外壳程序中运行的问题的示例查询.我不熟悉猫鼬，但是我想这仍然可以为您提供帮助，并且您可以翻译它:
I would suggest you take a look at the aggregation framework, as you'll get a lot more flexibility. Here's an example query for your question that runs in the shell. I'm not familiar with mongoose, but I guess this will still help you and you'd be able to translate it:
db.collection.aggregate([
// Get only the documents where "email" equals "test@test.com" -- REPLACE with params.username
{"$match" : {email : "test@test.com"}},
// Unwind the "inventories" array
{"$unwind" : "$inventories"},
// Get only elements where "inventories.title" equals "activeInventory"
{"$match" : {"inventories.title":"activeInventory"}},
// Unwind the "vehicles" array
{"$unwind" : "$inventories.vehicles"},
// Filter by vehicle ID -- REPLACE with vehicleID
{"$match" : {"inventories.vehicles._id":ObjectId("53440e94c02b3cae81eb0069")}},
// Tidy up the output
{"$project" : {_id:0, vehicle:"$inventories.vehicles"}}
])
这是您将获得的输出:
{
"result" : [
{
"vehicle" : {
"_id" : ObjectId("53440e94c02b3cae81eb0069"),
"tags" : [
"vehicle"
],
"details" : [
{
"_id" : ObjectId("53440e94c02b3cae81eb0066"),
"year" : 2007,
"transmission" : "Manual",
"price" : 1000,
"model" : "Firecar",
"mileageReading" : 50000,
"make" : "Bentley",
"interiorColor" : "blue",
"history" : "CarProof",
"exteriorColor" : "blue",
"driveTrain" : "SWD",
"description" : "test vehicle",
"cylinders" : 4,
"mileageType" : "kms"
}
]
}
}
],
"ok" : 1
}
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