我想将单独的集合组合到1个json，但是在嵌套$ lookup中有一些问题。
这是我的示例集合。 集合Package_subscriptions：
[
{
"_id": "1",
"package_name": "Small",
"package_desc": "AAA",
"package_price": 10
},
{
"_id": "2",
"package_name": "Medium",
"package_desc": "BBB",
"package_price": 20
}
集合Package_modules：
{
"_id" : 1,
"subscription_id" : 1,
"billing_model_id" : 1,
"module_id" : 1,
"created_at" : ISODate("2019-06-17T07:59:43.199Z"),
}
{
"_id" : 2,
"subscription_id" : 1,
"billing_model_id" : 3,
"module_id" : 2,
"created_at" : ISODate("2019-06-17T08:00:37.464Z"),
}
{
"_id" : 3,
"subscription_id" : 2,
"billing_model_id" : 2,
"module_id" : 1,
"created_at" : ISODate("2019-06-17T08:00:56.610Z"),
}
{
"_id" : 4,
"subscription_id" : 2,
"billing_model_id" : 4,
"module_id" : 2,
"created_at" : ISODate("2019-06-17T08:01:29.667Z"),
}
收集模块：
{
"_id" : 1,
"module_name" : "Call",
"status" : "Active",
}
{
"_id" : 2,
"module_name" : "SMS",
"status" : "Active",
}
集合Billing_models
{
"_id" : 1,
"unit_count" : "Menit",
"counter" : 2000,
},
{
"_id" : 2,
"unit_count" : "Menit",
"counter" : 3000,
}
{
"_id" : 3,
"unit_count" : "SMS",
"counter" : 3000,
},
{
"_id" : 4,
"unit_count" : "SMS",
"counter" : 5000,
}
这是我尝试解决此问题的代码，但是没有达到预期的效果。
Package_subscription
.aggregate([
{
$lookup: {
from: "o_package_modules",
localField: "_id",
foreignField: "subscription_id",
as: "package_modules"
}
},
{
$unwind: {
path: "$package_modules",
preserveNullAndEmptyArrays: true
}
},
{
$lookup: {
from: "o_modules",
localField: "package_modules.module_id",
foreignField: "_id",
as: 'module'
}
},
{
$lookup: {
from: "o_billing_models",
localField: "package_modules.billing_model_id",
foreignField: "_id",
as: 'billing_module'
}
}
])
.exec()
.then((pricing) => {
res.json(pricing)
})
.catch((err) => {
res.send(err)
})
我希望输出是：
[
{
"_id": "1",
"package_name": "Small",
"package_desc": "AAA",
"package_price": 10,
"package_modules": [
{
"_id": 1,
"subscription_id": 1,
"billing_model": {
"_id": 1,
"unit_count": "Menit",
"counter": 2000
},
"module": {
"_id": 1,
"module_name": "Call",
"status": "Active"
},
"created_at": "2019-06-17T07:59:43.199Z",
},
{
"_id": 2,
"subscription_id": 1,
"billing_model": {
"_id": 3,
"unit_count": "SMS",
"counter": 3000
},
"module": {
"_id": 2,
"module_name": "SMS",
"status": "Active"
},
"created_at": "2019-06-17T08:00:37.464Z",
}
]
},
{
"_id": 2,
"package_name": "Medium",
"package_desc": "BBB",
"package_price": 20,
"package_modules": [
{
"_id": 3,
"subscription_id": 2,
"billing_model": {
"_id": 2,
"unit_count": "Menit",
"counter": 3000
},
"module": {
"_id": "1",
"module_name": "Call",
"status": "Active"
},
"created_at": "2019-06-17T08:01:29.667Z",
},
{
"_id": 4,
"subscription_id": 2,
"billing_model": {
"_id": 4,
"unit_count": "SMS",
"counter": 5000
},
"module": {
"_id": 2,
"module_name": "SMS",
"status": "Active"
},
"created_at": "2019-06-17T08:01:50.285Z",
}
]
}
]
但是我的代码输出是：
[
{
"_id": "1",
"package_name": "Small",
"package_desc": "AAA",
"package_price": 10,
"package_modules": {
"_id": 1,
"subscription_id": 1,
"billing_model_id": 1
"module_id": 1
"created_at": "2019-06-17T07:59:43.199Z",
},
},
"billing_model": [
{
"_id": 1,
"unit_count": "Menit",
"counter": 2000
},
],
"module": [
{
"_id": 1,
"module_name": "Call",
"status": "Active"
}
]
},
{
"_id": "1",
"package_name": "Small",
"package_desc": "AAA",
"package_price": 10,
"package_modules": {
"_id": 2,
"subscription_id": 2,
"billing_model_id": 3
"module_id": 2
"created_at": "2019-06-17T07:59:43.199Z",
},
},
"billing_model": [
{
"_id": 3,
"unit_count": "SMS",
"counter": 3000
},
],
"module": [
{
"_id": 2,
"module_name": "SMS",
"status": "Active"
}
]
}
..........
// And medium where is loop again
]
答案 0 :(得分：0)
我认为您的代码中存在多个问题。
在您的$lookup阶段，您需要将as字段设置为package_modules.billing_module和package_modules.module，而不是billing_module和{{1 }}等，以使其成为module对象的字段，而不是单独的对象本身。
您需要在每个package_module阶段之后unwind，因为$lookup返回一个数组而不是对象。
您需要在$lookup管道的末尾$group来将一个订阅的所有aggregation push合并到一个数组中。
解决所有上述问题后， 您的聚合管道应如下所示：
package_modules最后一个Package_subscription
.aggregate([
{
$lookup: {
from: "o_package_modules",
localField: "_id",
foreignField: "subscription_id",
as: "package_modules"
}
},
{
$unwind: {
path: "$package_modules",
preserveNullAndEmptyArrays: true
}
},
{
$lookup: {
from: "o_modules",
localField: "package_modules.module_id",
foreignField: "_id",
as: 'package_modules.module'
}
},
{
$unwind: {
path: "$package_modules.module",
preserveNullAndEmptyArrays: true
}
},
{
$lookup: {
from: "o_billing_models",
localField: "package_modules.billing_model_id",
foreignField: "_id",
as: 'package_modules.billing_module'
}
},
{
$unwind: {
path: "$package_modules.billing_module",
preserveNullAndEmptyArrays: true
}
},
{
$group: {
_id: "$_id",
package_modules : {$push : "$package_modules"},
package_name: {$first . : "$package_name"},
package_desc: {$first . : "$package_desc"},
package_price: {$first . : "$package_price"}
}
}
])
.exec()
.then((pricing) => {
res.json(pricing)
})
.catch((err) => {
res.send(err)
})
阶段的$push将所有$group合并为一个数组。我认为那是您最后想要的。
我希望这对您有用。