field within the object of array in Mongodb

Question

The sample structure is as follows:

{
    "_id": 1,
    "College_name" : "abcdef"
    "Students": [
{
  "name": "a",
  "Grade": "First"
},
{
  "name": "b",
  "Grade": "Second"
},
{
  "name": "c",
  "Grade": "First"
},
{
  "name": "d",
  "Grade": "First"

}
]
}

What I am not getting is - I want to get all ("Grade" : "First") objects in the array and insert only ("Grade" : "First") objects to other collection where ("College_name" : "abcdef"). What is the optimal solution for this? Is this possible through aggregation?? Please help me out to solve this.

Bittu · Accepted Answer · 2014-09-10 13:07:02Z

0

You can fetch the data with {"Grade": "First"} either using aggregation or mongo query -

Aggregation query -

db.coll.aggregate([{'$match':{"Students.Grade":"First"}}, {$project: {"_id":1, "College_name":1}}])

Mongo Query -

db.coll.find({"Students.Grade":"First"}, {"College_name":1})

After that you can insert the data to other collection.

answered Sep 10, 2014 at 13:07

Bittu

487 bronze badges

Sign up to request clarification or add additional context in comments.

2 Comments

manojpt Over a year ago

Yes this works. But i want to retrieve only the objects with {"Grade": "First"} where ("College_name" : "abcdef"). i.e., output should not contain the sub document with (name : "b").

manojpt Over a year ago

Using $in and $ projection, we will get only the first matched element in the array. How would we get multiple matched elements??

Community · Accepted Answer · 2017-05-23 12:20:34Z

0

Answer to this question is in the link:

query to retrieve multiple objects in an array in mongodb

i.e., Aggregation query will have 4 pipeline operators:

  [match, unwind, match, group]

and then can be inserted to the other collection.

edited May 23, 2017 at 12:20

CommunityBot

11 silver badge

answered Jan 16, 2015 at 13:14

manojpt

1,2892 gold badges13 silver badges20 bronze badges

Collectives™ on Stack Overflow

field within the object of array in Mongodb

2 Answers 2

2 Comments

Comments

Your Answer

Linked

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

2 Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Linked

Related