Help with conditional 'unless' statement

[Jon_Girard]

I need help getting my 'unless' statement to work. It's checking to see whether or not a db entry with the same date and user info already exists before it creates a new one.

Unfortunatley, it doesn't seem to work. It allows duplicate entries to be made.

class Tweet < ActiveRecord::Base
  def self.get_latest
    Twitter::Search.new.hashtag("somesearch").fetch.each do |tweet_results| #hit the API.
      twitter_created_at = DateTime.parse(tweet_results.created_at)
      unless Tweet.exists?(['twitter_created_at = ? AND from_user_id_str = ?', DateTime.parse(tweet_results.created_at), tweet_results.from_user_id_str])
        Tweet.create!({
          :from_user => tweet_results.from_user,
          :from_user_id_str => tweet_results.from_user_id_str,
          :profile_image_url => tweet_results.profile_image_url,
          :text => tweet_results.text, 
          :twitter_created_at => twitter_created_at 
          })
      end
    end
  end
end

Ideas?

[wadjorlolo]

I think you need to provide an exit action; you haven't created parameters for what occurs if a duplicate is found in your DB.

Perhaps if you use an if/else statement:

if Tweet.exists?(['twitter_created_at = ? AND from_user_id_str = ?', DateTime.parse(tweet_results.created_at), tweet_results.from_user_id_str])
      prints "Generic Error Message" #This would be your response to a duplicate
else
      Tweet.create!({
          :from_user => tweet_results.from_user,
          :from_user_id_str => tweet_results.from_user_id_str,
          :profile_image_url => tweet_results.profile_image_url,
          :text => tweet_results.text, 
          :twitter_created_at => twitter_created_at 
          })
      end
    end
  end
end

Also, you seem to have 2 variables buried in a string with a #{} to separate them from the string. Is that intentional?

[wadjorlolo]

Correction:

Also, you seem to have 2 variables buried in a string WITHOUT a #{} to separate them from the string. Is that intentional?

[Louis Simoneau]

@wadjorlolo: the #{} syntax shouldn't be used for passing variables into database queries, as Jon is doing here. The reason is that SQL code could be injected into the string, and your app will pass it straight on to the database, which could open you up to attacks.

The syntax Jon is using is more secure, and is described in detail here: http://guides.rubyonrails.org/active...ray-conditions

[wadjorlolo]

@wadjorlolo: the #{} syntax shouldn't be used for passing variables into database queries, as Jon is doing here. The reason is that SQL code could be injected into the string, and your app will pass it straight on to the database, which could open you up to attacks.

The syntax Jon is using is more secure, and is described in detail here: http://guides.rubyonrails.org/active...ray-conditions

Thanks for the correction, I am currently parsing my way through The Rails 3 Way. Very informative.