我需要通過在嵌套在對象中的數組中的查找對象的幫助

Question

school object :{ 
    "id":"school1" 
    "adress":"aaaaa" 
    "studentInfo":{ 
     "details" : [ 
      { 
       "class" : "a", 
       "studentId" : "dan", 
       "subject" : "math", 

      }, 
      { 
       "class" : "b", 
       "studentId" : "ron", 
       "subject" : "math", 

      } 
     ] 
    } 
} 

我有一個問題，從詳細數組中獲取特定對象的問題。 我期望的結果是由studentId發現：

{ 
    "class" : "a", 
    "studentId" : "dan", 
    "subject" : "math", 
} 

我想：提前

db.getCollection('schools').find(
    {'name':'school1'}, 
    {'studentInfo.details':{$elemMatch:{'studentId':'dan'} } } 
) 

感謝

Answer 1

這是做這件事的一種方法：下面是shell命令：

db.schools.find({"id" : "school1", "studentInfo.details.studentId" :"dan"}, {"studentInfo.details.$" : 1}) 

Answer 2

db.findOne({ studentId: "dan" })