Node.js 如何在mongoose中组合嵌套$lookup 3级别？

我想将单独的集合合并为1个json，但嵌套$lookup中存在一些问题

这是我的示例集合。 集合包订阅：

[
    {
        "_id": "1",
        "package_name": "Small",
        "package_desc": "AAA",
        "package_price": 10
    },
    {
        "_id": "2",
        "package_name": "Medium",
        "package_desc": "BBB",
        "package_price": 20    
    }

收集软件包\u模块：

{
    "_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",
}

收费模式

{
    "_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,
}

这是我尝试解决这个问题的代码，但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)
            })

我预计结果是：

[
    {
        "_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",
            }
        ]
    }
]

但我的代码的输出是：

[
    {
        "_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
]

---

我认为您的代码中存在多个问题

在

$lookup

阶段，您需要将

设置为
软件包模块。计费模块
和
软件包模块。模块
而不是
计费模块
和
模块
，依此类推，这样，它就变成了
package\u模块
对象的字段，而不是单独的对象本身

在每个

$lookup

阶段之后，您需要

展开

，因为

$lookup

返回一个数组而不是一个对象

您需要在

聚合

管道的末尾

$group

将一个订阅的所有

打包模块

推送到一个阵列中

在解决了上述所有问题之后,， 您的聚合管道应如下所示：

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)
        })

最后一个

$group

阶段中的

$push

将把所有

封装模块组合成一个阵列。我想这就是你最后想要的

我希望这对您有用。
我认为您的代码中存在多个问题

在
$lookup
阶段，您需要将
设置为
软件包模块。计费模块
和
软件包模块。模块
而不是
计费模块
和
模块
，依此类推，这样，它就变成了
package\u模块
对象的字段，而不是单独的对象本身

在每个
$lookup
阶段之后，您需要
展开
，因为
$lookup
返回一个数组而不是一个对象

您需要在
聚合
管道的末尾
$group
将一个订阅的所有
打包模块
推送到一个阵列中

在解决了上述所有问题之后,，
您的聚合管道应如下所示：

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)
        })

最后一个
$group
阶段中的
$push
将把所有
封装模块组合成一个阵列。我想这就是你最后想要的

我希望这对你有用