Date Queries in MongoDB
Far too many times have I wanted to do a query on a date in MongoDB, only to find there is literally no documentation on it. So, in order that I shall not forget for next time, I thought I’d post it here.
I’m sure there are probably other methods, but here is one using the $where expression. The $where expression is pretty awesome, it lets you evaluate an arbitrary JavaScript expression, where this is populated with the current document being checked. So, we just compare it to a JavaScript date object.
db.collection.find({$where: "this.date_field > new Date(2009, 11, 02)"})
Now I shall never forget again :)
Comments
Subscribe Make commentNice tip, thanks for the post. I was also finding the MongoDB documentation lacking when it comes to using dates.
Note that the JavaScript “new Date” constructor uses a zero-based month number. So in this example, the search is filtering for dates greater than December 2, 2009 _not_ November 2, 2009. To see for yourself, enter the command at the MongoDB console:
> new Date(2009, 11, 02)
“Wed Dec 02 2009 00:00:00 GMT-0800 (PST)”
Indeed, very good point about javascript date weirdness.
I tend to just do Date(‘DD/MM/YYYY’) as a string these days, and it saves a lot of confusion.
It works but will it take use of the indexes??
The where clause would evaluate each document with this expression;
This is true, I’m guessing no indexing would be taken into account here.
In pymongo, I’d just pass the datetime object and everything would be fine, but for the shell I couldn’t find any way to do it, hence this not too great method.
I guess I could look into the pymongo source to find out how they do it, which I’m guessing is the “proper” way.