I have some code written in Ruby 1.9.2 patch level 136 and I'm have an issue where when I perform a find via the _id in the raw ruby mongo driver I get a nil when trying to use a value from a csv file. Here's the code:
require 'mongo'
require 'csv'
require 'bson'
# Games database
gamedb = Mongo::Connection.new("localhost", 27017).db("gamedb")
@games = gamedb.collection("games")
# Loop over CSV data.
CSV.foreach("/tmp/somedata.csv") do |row|
puts row[0] # Puts the ObjectId
@game = @games.find( { "_id" => row[0] } ).first
puts @game.inspect
end
The CSV file looks like this:
_id,game_title,platform,upc_db_match,upc
4ecdacc339c7d7a2a6000002,TMNT,PSP,TMNT,085391157663
4ecdacc339c7d7a2a6000004,Super Mario Galaxy,Wii,Super Mario Galaxy,045496900434
4ecdacc339c7d7a2a6000005,Beowulf,PSP,Beowulf,097363473046
The first column is the objectId in Mongo that I already have. If I perform a local find from the mongo command line the values in the first column, I get the data I want. However, the code above returns nil on the @game.inspect call.
I've tried the following variations, which all produce nil:
@game = @games.find( { "_id" => row[0].to_s } ).first
@game = @games.find( { "_id" => row[0].to_s.strip } ).first
I've even tried building the ObjectId with the BSON classes as such:
@game = @games.find( { "_id" => BSON::ObjectId(row[0]) } ).first
or
@game = @games.find( { "_id" => BSON::ObjectId("#{row[0]}") } ).first
Both of which output the following error:
/Users/donnfelker/.rvm/gems/ruby-1.9.2-p136@upc-etl/gems/bson-1.4.0/lib/bson/types/object_id.rb:126:in `from_string': illegal ObjectId format: _id (BSON::InvalidObjectId)
from /Users/donnfelker/.rvm/gems/ruby-1.9.2-p136@upc-etl/gems/bson-1.4.0/lib/bson/types/object_id.rb:26:in `ObjectId'
from migrate_upc_from_csv.rb:14:in `block in <main>'
from /Users/donnfelker/.rvm/rubies/ruby-1.9.2-p136/lib/ruby/1.9.1/csv.rb:1768:in `each'
from /Users/donnfelker/.rvm/rubies/ruby-1.9.2-p136/lib/ruby/1.9.1/csv.rb:1202:in `block in foreach'
from /Users/donnfelker/.rvm/rubies/ruby-1.9.2-p136/lib/ruby/1.9.1/csv.rb:1340:in `open'
from /Users/donnfelker/.rvm/rubies/ruby-1.9.2-p136/lib/ruby/1.9.1/csv.rb:1201:in `foreach'
from migrate_upc_from_csv.rb:10:in `<main>'
The crazy thing is, if I manually create the BSON ObjectId by hand it works (as shown below):
@game = @games.find( { "_id" => BSON::ObjectId("4ecdacc339c7d7a2a6000004") } ).first
When I run @game.inspect I get my data back, as I would expect. However, If I change this to use row[0], I get nil.
Why? What am I doing wrong?
System Details
$ gem list
*** LOCAL GEMS ***
bson (1.4.0)
bson_ext (1.4.0)
mongo (1.4.0)
RVM Version: rvm 1.6.9
Ruby Version: ruby 1.9.2p136 (2010-12-25 revision 30365) [x86_64-darwin10.6.0]
Mongo Version:
[initandlisten] db version v1.8.2, pdfile version 4.5
[initandlisten] git version: 433bbaa14aaba6860da15bd4de8edf600f56501b
Again, why? What am I doing wrong here? Thanks!
The first row is not being read as a header, to do that pass in :headers => true like this:
require 'csv'
# Loop over CSV data.
CSV.foreach("/tmp/somedata.csv", :headers => true) do |row|
puts row[0] # Puts the ObjectId
end
If you do not pass the :headers parameter in you can see the first row[0] object is the string "_id":
_id
4ecdacc339c7d7a2a6000002
4ecdacc339c7d7a2a6000004
4ecdacc339c7d7a2a6000005
When you include it, you are golden:
4ecdacc339c7d7a2a6000002
4ecdacc339c7d7a2a6000004
4ecdacc339c7d7a2a6000005