how to save a result from a mongodb query into a javascript variable?

Question

there are some questions here regarding how to save a result from a query into a javascript varialbe, but I'm just not able to implement them. The point is that I have a much difficult query, so this question is, in my opinion, unique.

Here is the problem. I have a collection namend "drives" and a key named "driveDate". I need to save 1 variable with the smallest date, and other with the biggest date.

The query for the smallest date is:

> db.drives.find({},{"_id":0,"driveDate":1}).sort({"driveDate":1}).limit(1)

The result is:

{ "driveDate" : ISODate("2012-01-11T17:24:12.676Z") }

how dan I save this to a variable, can I do something like:

tmp = db.drives.find({},{"_id":0,"driveDate":1}).sort({"driveDate":1}).limit(1)

Thanks!!!

Where is your query being run? Is it on the server side? Or is it being run on the client end? — Ivan
– Ivan, Commented Dec 2, 2012 at 19:13
@Ivan, the query is direct on the mongo console. (with the command "mongo"). The DB is locally installed on my machine. I already figured out how to make it. thanks. — otmezger
– otmezger, Commented Dec 3, 2012 at 8:18

JohnnyHK · Accepted Answer · 2012-12-02 21:58:01Z

14

Assuming you're trying to do this in the shell:

 tmp = db.drives.find({}, {_id:0, driveDate:1}).sort({driveDate:1}).limit(1).toArray()[0]

find returns a cursor that you need to iterate over to retrieve the actual documents. Calling toArray on the cursor converts it to an array of docs.

edited Dec 2, 2012 at 21:58

answered Dec 2, 2012 at 19:32

JohnnyHK

313k70 gold badges632 silver badges479 bronze badges

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

4 Comments

Sammaye Over a year ago

I am unsure if sort() works on findOne since it does not return a cursor as such the chain will have no function of sort()

otmezger Over a year ago

Hi, thanks for your answer. I keep getting this error: "Sun Dec 2 21:58:13 TypeError: db.drives.findOne({}, {_id:0, driveDate:1}).sort is not a function (shell):1"... somehow findOne can't work with sort

JohnnyHK Over a year ago

@otmezger Sorry about that, Sam's right, there doesn't seem to be a way to sort with findOne in the shell. See updated answer.

naXa stands with Ukraine Over a year ago

I'd like to share my wtf experience. I was doing let tmp = db.collection.aggregate(...).map(doc => doc._id) in IntelliJ IDEA DataGrip to later use the variable in another query $match: { "foo": { $in: tmp } }. But I faced WriteAbortedException; NotSerializableException: TruffleStackTraceElement error. The solution was to append .toArray() as in your example. Thank you!

otmezger · Accepted Answer · 2012-12-03 07:59:36Z

5

After some time figuring out, I got the solution. here it is, for future reference:

var cursor = db.drives.find({},{"_id":1}).sort({"driveDate":1}).limit(1)

Then I can get the document from the cursor like this

var myDate = cursor.next()

That's it. Thanks for your help

answered Dec 3, 2012 at 7:59

otmezger

10.8k21 gold badges69 silver badges92 bronze badges

Collectives™ on Stack Overflow

how to save a result from a mongodb query into a javascript variable?

2 Answers 2

4 Comments

Comments

Your Answer

Linked

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

4 Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Linked

Related