Using db.find().map with pymongo

Question

I am porting a program written in server side javascript to python using pymongo. The javscript program uses this syntax:

db.dbname.find(pattern1,pattern2).map( function(i){functionname(i) })

Pattern1 and pattern2 are valid mongodb query patterns. Functionname is a valid javascript function. All are defined in the javascript source file. I have searched the documentation but can't seem to find a pymongo find().map function (as opposed to map_reduce.)

How would this be re written in python?

Answer 1

You can just see what is map function in javascript doing. Map is a part of functional programming, but what it is doing can be simply described as follows: it is taking an array and modify every element in an array based on the function provided. You can think about it as a loop.

So you need to do the same loop in python. With comprehensions it will be something like this:

[functionname(i) for i in resultFromMongo]

Checkout this for a reference.

• Hamed Damirchi: the map function in mongodb works in database side and the map function in python works in application side. so using mongodb's map is so much efficient than python's map function (though it doesn't have significant difference in small amount of data)