Mongoid Undefined method [] for nil:nilClass

Question

I have an application that queries an API and then attempts to store that query in the Mongo document. It seems pretty straightforward from the documentation, but I seem to be missing a step, but I have little idea of what's wrong. Could one of you point me in the right direction? Thanks!

I have a line that selects some records from the DB, then runs a loop querying the API. I run into the error undefined method[]' for nil:NilClass` when the program reaches the line

EntityMetadata.where(id: c['id'].to_s).add_to_set(:mood, result["mood"])

The console also outputs this: MOPED: 127.0.0.1:27017 COMMAND database=admin command={:ismaster=>1} , which I have no idea how it got there.

This is the full code if you're interested

puts "Getting sentiment for all entities from Viralheat..."
api_key = '___________------_____-----'
puts "a"
base_uri 'viralheat.com/api/sentiment'

content_sql = 'SELECT content,id FROM entities'   
puts content_sql

content = ActiveRecord::Base.connection.select_all(content_sql , "Entity Content")
query = {:api_key => api_key}
asdf = {}
content.each do |c| 
   puts c["content"]
   puts "Getting Sentiment for " + c["content"].to_s 
   query[:text] = c["content"]
   result = self.get('/review.json', :query => query)
   puts "asdf"
   EntityMetadata.where(id: c['id'].to_s).add_to_set(:mood, result["mood"])
   puts "ss"
   EntityMetadata.where(id: c['id'].to_s).add_to_set(:prob, result["prob"])
   #update_mood_sql = "UPDATE entities SET mood = '#{result["mood"]}' WHERE id ='" + c["id"].to_s + "'"
   #update_prob_sql = "UPDATE entities SET probability = '#{result["prob"]}' WHERE id ='" + c["id"].to_s + "'"
   #ActiveRecord::Base.connection.update_sql(update_mood_sql, "Updating mood")
   #ActiveRecord::Base.connection.update_sql(update_prob_sql, "Updating prob")  
end

Here is the model code:

class EntityMetadata
  include Mongoid::Document
  field :_id, type: Integer
  field :fingerprint, type: String
  index({ fingerprint: 1 }, { sparse: true })

  # TODO: change this to use the entity_id as the :_id field, to save space
  # field :entity_id, type: Integer
  # index({ entity_id: 1 }, { unique: true })

  def entity
    @entity ||= Entity.find_by_id(self._id)
  end
end

thanks for the suggestion. didn't understand the etiquette around here. — BBB
– BBB, Commented Aug 25, 2012 at 7:08

Tigraine · Accepted Answer · 2012-08-25 09:45:52Z

1

Purely from the error message I would say that the problem has nothing to do with Mongoid but rather with either c or result:

EntityMetadata.where(id: c['id'].to_s).add_to_set(:mood, result["mood"])

If any of these two is not set (nil) then the statement fails and you never actually reach Mongoid.

Try using pry (pry-rails) and insert a binding.pry on the line above to inspect these two variables to see if none of them are nil.

answered Aug 25, 2012 at 9:45

Tigraine

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2 Comments

BBB Over a year ago

I tried using a puts statement, and the value of c['id].to_s is 1 and the value of result["mood"] is negative, so neither of these are null

Tigraine Over a year ago

Very strange.. sorry but I am at a loss then.. maybe you can post your model code? You may also want to remove the api key from the question though..

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