我有一个包含一组模块的课程集，每个模块都有一组主题，每个主题都有一组单元。
课程合集：
{
"course": {
"_id": "612f5605dc3813a3717663fe",
"cmodules": [
"612f5612dc3813068b76646c"
"612f561adc3813e7a27664f6",
],
"title": "C++ Complete Course"
}
}
模块合集：
{
"cmodules": [
{
"_id": "612f561adc3813e7a27664f6",
"topics": [
"612f561bdc381332647664fd"
"612f5615dc3813d8a47664bb",
"612f5617dc38130e017664de"
],
"title": "Welcome to C++",
"desc": "C++ Introduction",
},
{
"_id": "612f5612dc3813068b76646c",
"topics": [
"612f5612dc3813ef8c766473"
"612f561cdc38132d73766514",
"612f561fdc3813ad1676652d"
],
"title": "Introduction to STL",
"desc": "Learn Standard template library",
}
]
}
话题合集：
{
"topics": [
{
"_id": "612f561bdc381332647664fd",
"units": [
"612f561bdc3813154b766503",
"612f561cdc3813feba76650b"
],
"order": 0,
"title": "Session 1",
},
{
"_id": "612f561cdc38132d73766514",
"units": [
"612f561ddc381317b176651a",
"612f561ddc38135e3a766520",
"612f561edc3813bf45766526"
],
"title": "Session 2",
},
{
"_id": "612f561fdc3813ad1676652d",
"units": [
"612f5620dc3813491b766533",
"612f5620dc3813b5f2766539",
"612f5621dc381387d976653f"
],
"title": "Session 3",
}
]
}
我learnedUnits在用户详细信息的数组（）中跟踪学生访问的所有单元 ID 列表。
我做了一些聚合管道和展开收集，直到模块。看看我的聚合结果。
[
{
"_id": "5fd5c105694d122f4837fa0f",
"learningPath": {
"historyCourses": {
"_id": "612f5605dc3813a3717663fe",
"startedAt": "2021-09-03T13:58:32.071Z",
"learnedUnits": [
"612f5608dc38133ee6766411",
"61322aa16c985ae927308a82",
"612f5608dc3813268a766417",
"612f5609dc38137cd776641d"
],
"course": {
"_id": "612f5605dc3813a3717663fe",
"cmodules": {
"_id": "612f5612dc3813068b76646c",
"topics": [
{
"_id": "612f5612dc3813ef8c766473",
"units": [
"612f5613dc381382797664ac",
"612f5614dc38139a927664b2"
],
"title": "Session 1",
},
{
"_id": "612f5615dc3813d8a47664bb",
"units": [
"612f5615dc38131ee17664c8",
"612f5616dc381317fa7664ce",
"612f5616dc38132ac37664d5"
],
"title": "Session 2",
},
{
"_id": "612f5617dc38130e017664de",
"units": [
"612f5618dc381399cf7664e4",
"612f5618dc38138e367664ea",
"612f5619dc38137fe87664f0"
],
"title": "Session 3",
}
],
"title": "Welcome to C++",
"desc": "C++ Introduction",
},
"title": "C++ Complete Course",
}
}
}
},
{
"_id": "5fd5c105694d122f4837fa0f",
"learningPath": {
"historyCourses": {
"_id": "612f5605dc3813a3717663fe",
"startedAt": "2021-09-03T13:58:32.071Z",
"learnedUnits": [
"612f5608dc38133ee6766411",
"61322aa16c985ae927308a82",
"612f5608dc3813268a766417",
"612f5609dc38137cd776641d"
],
"course": {
"_id": "612f5605dc3813a3717663fe",
"cmodules": {
"_id": "612f561adc3813e7a27664f6",
"topics": [
{
"_id": "612f561bdc381332647664fd",
"units": [
"612f561bdc3813154b766503",
"612f561cdc3813feba76650b"
],
"order": 0,
"title": "Session 1",
},
{
"_id": "612f561cdc38132d73766514",
"units": [
"612f561ddc381317b176651a",
"612f561ddc38135e3a766520",
"612f561edc3813bf45766526"
],
"title": "Session 2",
},
{
"_id": "612f561fdc3813ad1676652d",
"units": [
"612f5620dc3813491b766533",
"612f5620dc3813b5f2766539",
"612f5621dc381387d976653f"
],
"title": "Session 3",
}
],
"title": "Introduction to STL",
"desc": "Learn Standard template library",
},
"title": "C++ Complete Course",
}
}
}
}
]
我想在这里做两件事。首先，我想按课程 ID 对所有聚合集合进行分组。模块应该作为课程的数组来收集。有些人认为如下。
{
"_id": "5fd5c105694d122f4837fa0f",
"learningPath": {
"historyCourses": {
"_id": "612f5605dc3813a3717663fe",
"startedAt": "2021-09-03T13:58:32.071Z",
"learnedUnits": [
"612f5608dc38133ee6766411",
"61322aa16c985ae927308a82",
"612f5608dc3813268a766417",
"612f5609dc38137cd776641d"
],
"course": {
"_id": "612f5605dc3813a3717663fe",
"cmodules": [
{
"_id": "612f5612dc3813068b76646c",
"topics": [
{
"_id": "612f5612dc3813ef8c766473",
"units": [
"612f5613dc381382797664ac",
"612f5614dc38139a927664b2"
]
}
]
},
{
"_id": "612f561adc3813e7a27664f6",
"topics": [
{
"_id": "612f561bdc381332647664fd",
"units": [
"612f561bdc3813154b766503",
"612f561cdc3813feba76650b"
]
}
]
}
]
}
}
}
}
其次，我想通过阅读learnedUnits课程单元来找到学生的平均完成百分比。在我上面的例子中，用户访问了 4 个单元。如果结合所有模块和主题的单元总数为 20，那么我想找到访问单元的平均值为 20%。
有没有办法在同一个聚合管道中做到这一点？