mongodb: query for values (not objects) in list

Question

I have a database with documents like

{_id: 5,
 fruit: 'apple',
 vitamins: ['B1', 'B12', 'A1']
}
{_id: 7,
 fruit: 'appricot',
 vitamins: ['B6', 'D12', 'A1']
}

Is there a way to query for all the records which have e.g. vitamin 'A1'?

I am looking for a mongo shell query and a pymongo equivalent. I know that I can put a for loop to iterate over records and check whether the list contains an element or no, but I prefer a query if there is one.

As it is a list and not a list of objects so seems I can't use $elemMatch...

Thanks

A simple find query like db.collection.find({"vitamins":"A1"}) should work just fine. Did you try it? — Anand Jayabalan
– Anand Jayabalan, Commented May 6, 2014 at 17:05
of course I did, it doesn't work... With the query you wrote, I expect to get the records which have "vitamins":"A1", exactly "A1" and nothing more. — gevra
– gevra, Commented May 6, 2014 at 17:15
Got it. You have 2 options: 1) Use the index in the projection like db.collection.find({"vitamins":"A1"}, {"fruit":1, "vitamins.$":1}) 2) Aggregation framework — Anand Jayabalan
– Anand Jayabalan, Commented May 6, 2014 at 17:19

Anand Jayabalan · Accepted Answer · 2014-05-06 17:24:31Z

2

You have a couple of options:

Option 1: If you want to match just one element, you could use the index in projection

db.collection.find({"vitamins":"A1"}, {"fruit":1, "vitamins.$":1})

Option 2: If you want to able to match multiple elements in the array, you can look at the aggregation framework:

db.collection.aggregate([{$unwind:"$vitamins"}, {$match:{"vitamins":"A1"}}])

answered May 6, 2014 at 17:24

Anand Jayabalan

13.1k6 gold badges43 silver badges54 bronze badges

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

1 Comment

gevra Over a year ago

Thanks @Anand! Tried Option 1, works fine. Still need to read more about the aggregation framework, I don't yet understand it properly.

Collectives™ on Stack Overflow

mongodb: query for values (not objects) in list

1 Answer 1

1 Comment

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

1 Comment

Your Answer

Sign up or log in

Post as a guest

Related