title: Run a rake db:seed multiple times without creating duplicate records?
body: <p>I have some code in a seed file that I'd like to alter so that it does not create duplicate records when I run the seed command multiple times. Any way to adapt the code below from my seeds file so that this is possible? The find_or_create_by method doesn't appear to work here unless I am mistaken.</p>
  
  <pre><code>data_file = Rails.root.join('db/data/data.csv')
  
  CSV.foreach(data_file) do |row|
    TownHealthRecord.create(
      city: row[0],
      state: row[1],
      country: row[2],
      zip_code: row[3],
      area_code: row[4]
      )
  end
  </code></pre>