Question

I have a class method Juxtaposition.generate_for(position) on a class that I am calling from a spec. The method sets up a map reduce and calls it map_reduce(map, reduce).out(merge: "juxtapositions")

The position variable is defined in a let prior to the it block.

When executing if I simply call the function above (which is really only calling a map reduce on data related to the position) then tests like below fail:

Juxtaposition.count.should eq 1
Juxtaposition.first.value.should eq values

However, if I call

Juxtaposition.generate_for(positions).first["value"].should eq values

prior to the two tests then they both pass. The above two tests also pass when I use pry and call the generate_for method from there.

Is there some strange behavior of map reduce in mongoid that I should be aware of? Or, is there some way to force the results into my later queries.

Answer 1

Solution was simple enough. I just need to make sure to call find on the call to map reduce.

More specifically:

map_reduce(map, reduce).out(merge: "juxtapositions").first

or

map_reduce(map, reduce).out(merge: "juxtapositions").to_a

Without to_a or first the actual map reduce doesn’t execute it seems, even if it’s meant to be stored in another collection.