Extract a particular element from a nested array in MongoDB

Extract a particular element from a nested array with the help of dot(.) notation. Let us first create a collection with documents −

> db.extractParticularElementDemo.insertOne(
...    {
...       "_id" : 101,
...       "StudentName" : "John",
...       "StudentInformation" : [
...          {
...             "Age" : 21,
...             "StudentPersonalInformation" : [
...                {
...                   "StudentNickName" : "Mike",
...                   "StudentFamilyDetails" : [
...                      {
...                         "FatherName" : "Carol"
...                      }
...                   ]
...                },
...                {
...                   "StudentAnotherName" : "David",
...                   "StudentFamilyDetails" : [
...                      {
...                         "FatherName" : "Robert"
...                      }
...                   ]
...                }
...             ]
...          }
...       ]
...    }
... );
{ "acknowledged" : true, "insertedId" : 101 }

Following is the query to display all documents from a collection with the help of find() method −

> db.extractParticularElementDemo.find().pretty();

This will produce the following output −

{
   "_id" : 101,
   "StudentName" : "John",
   "StudentInformation" : [
      {
         "Age" : 21,
         "StudentPersonalInformation" : [
            {
               "StudentNickName" : "Mike",
               "StudentFamilyDetails" : [
                  {
                     "FatherName" : "Carol"
                  }
            ]
         },
         {
            "StudentAnotherName" : "David",
            "StudentFamilyDetails" : [
               {
                  "FatherName" : "Robert"
               }
         ]
      }
   ]
}
]
}

Following is the query to extract particular element from a nested array −

> db.extractParticularElementDemo.find(
... {'StudentInformation.StudentPersonalInformation.StudentFamilyDetails.FatherName':'Carol'},
... {'StudentInformation.StudentPersonalInformation.StudentFamilyDetails.FatherName':1,"_id":0}
... ).pretty();

This will produce the following output −

{
   "StudentInformation" : [
      {
         "StudentPersonalInformation" : [
            {
               "StudentFamilyDetails" : [
                  {
                  }
                  "FatherName" : "Carol"
               ]
            },
            {
               "StudentFamilyDetails" : [
                  {
                     "FatherName" : "Robert"
                  }
               ]
            }
         ]
      }
   ]
}

AmitDiwan

Updated on 27-Mar-2020 11:49:28

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