根据MongoDB中的条件从嵌入式文档合并数组

Question

我收集了如下的学生详细信息：

  {
    "Student_id": 1,
    "StudentName": "ABC",
    "TestDetails": [{
            "SubtestName":"Reading", "TestSeq":1, "SubTestDetails":1, 
            "Scores":[{"ScoreType":"YY","ScoreValue":"100"},{"ScoreType":"XX","ScoreValue":"100"},
            {"ScoreType": "ZZ","ScoreValue":"100"}]}]
  ,
    "TestDetails": [{
            "SubtestName":"Writing", "TestSeq":1, "SubTestDetails":2, 
            "Scores":[{"ScoreType":"YY","ScoreValue":"200"},{"ScoreType":"XX","ScoreValue":"200"},
            {"ScoreType": "ZZ","ScoreValue":"200"}]}]
  ,
    "TestDetails": [{
            "SubtestName":"Listning", "TestSeq":2, "SubTestDetails":3, 
            "Scores":[{"ScoreType":"YY","ScoreValue":"300"},{"ScoreType":"XX","ScoreValue":"300"},
            {"ScoreType": "ZZ","ScoreValue":"300"}]}]
  ,
    "TestDetails": [{
            "SubtestName":"Speaking", "TestSeq":2, "SubTestDetails":4, 
            "Scores":[{"ScoreType":"YY","ScoreValue":"400"},{"ScoreType":"XX","ScoreValue":"400"},
            {"ScoreType": "ZZ","ScoreValue":"400"}]}]
  ,
    "TestDetails": [{
            "SubtestName":"Smartness", "TestSeq":3, "SubTestDetails":5, 
            "Scores":[{"ScoreType":"YY","ScoreValue":"500"},{"ScoreType":"XX","ScoreValue":"500"},
            {"ScoreType": "ZZ","ScoreValue":"500"}]}]
  },

  {
    "Student_id": 2,
    "StudentName": "XYZ",
    "TestDetails": [{
            "SubtestName":"Smartness", "TestSeq":1, "SubTestDetails":1, 
            "Scores":[{"ScoreType":"YY","ScoreValue":"100"},{"ScoreType":"XX","ScoreValue":"100"},
            {"ScoreType": "ZZ","ScoreValue":"100"}]}]
  ,
    "TestDetails": [{
            "SubtestName":"Writing", "TestSeq":1, "SubTestDetails":2, 
            "Scores":[{"ScoreType":"YY","ScoreValue":"200"},{"ScoreType":"XX","ScoreValue":"200"},
            {"ScoreType": "ZZ","ScoreValue":"200"}]}]
  ,
    "TestDetails": [{
            "SubtestName":"Listning", "TestSeq":2, "SubTestDetails":3, 
            "Scores":[{"ScoreType":"YY","ScoreValue":"300"},{"ScoreType":"XX","ScoreValue":"300"},
            {"ScoreType": "ZZ","ScoreValue":"300"}]}]
  ,
    "TestDetails": [{
            "SubtestName":"Speaking", "TestSeq":2, "SubTestDetails":4, 
            "Scores":[{"ScoreType":"YY","ScoreValue":"400"},{"ScoreType":"XX","ScoreValue":"400"},
            {"ScoreType": "ZZ","ScoreValue":"400"}]}]
  ,
    "TestDetails": [{
            "SubtestName":"Reading", "TestSeq":3, "SubTestDetails":5, 
            "Scores":[{"ScoreType":"YY","ScoreValue":"100"},{"ScoreType":"XX","ScoreValue":"100"},
            {"ScoreType": "ZZ","ScoreValue":"1000"}]}]
  }, 
  .
  .
  .
)

如何创建聚合查询以生成如下文档：

{Student:1, "TestSeq" : 1, [{Subtest_name: Reading},{Subtest_name: Writing}]},
{Student:1,"TestSeq" :  2, [{Subtest_name: Listning},{Subtest_name: Speaking}]},
{Student:1, "TestSeq" : 3, [{Subtest_name: Smartness}]},
{Student:2, "TestSeq" : 1, [{Subtest_name: Smartness},{Subtest_name: Writing}]},
{Student:2, "TestSeq" : 2, [{Subtest_name: Listning},{Subtest_name: Speaking}]},
{Student:2, "TestSeq" : 3, [{Subtest_name: Reading}]},
{Student:3, "TestSeq" : 1, [{Subtest_name: Subtest1},{Subtest_name: Subtest2}]},
{Student:3, "TestSeq" : 2, [{Subtest_name: Subtest3},{Subtest_name: Subtest4}]},
{Student:3, "TestSeq" : 3, [{Subtest_name: Subtest5}]}

逻辑是根据TestSeq值对子测试名称进行组合/分组。 例如，为TestSeq = 1组合了子测试名称，对于值2，它位于第二行，对于每个学生，最后一个子测试名称是3。

我该如何实施？

我尝试了如下-

db.students.aggregate([ 
{$unwind: "$SubtestAttribs"},
{ $project: { student_name: 1, student_id : 1,
 print_ready : "$SubtestAttribs.TestSeq",
 Subtest_names :$SubtestAttribs.SubtestName" } } ])

但是我无法根据条件形成数组。 上面的代码段提供了每个测试序列的数据。 但是如何根据测试序列来组合两个子测试名称呢？

Answer 1

注意：我做几个假设，因为您的问题中包含一些非法的JSON。 让我知道我猜错了。 另外，我现在不在装有Mongo的计算机上，因此我可能会遇到一些语法问题。

db.students.aggregate([
{ $unwind: "$TestDetails" },
{
    $group:{
        _id: { Student: "$Student_id", TestSeq: "$TestDetails.TestSeq},
        Subtest_names: { $addToSet: "$TestDetails.Subtestname" }
    }
},
{
    $project:{
        Student: "$_id.Student",
        TestSeq: "$_id.TestSeq,
        Subtest_names: "$Subtest_names"
    }
}
])