using COPY FROM in a Rails app on Heroku with the Postgresql backend

Question

I want to give users the option of uploading files in my Ruby on Rails 3.2 application, with the data going into the db. I wanted to use the COPY FROM command s

Answer 1

You can use the gem https://github.com/diogob/postgres-copy Assuming data is an IO object.

User.copy_from data, columns: [:name, :taxon_id, :updated_at, :created_at]

Or using the path to the uploaded file directly:

User.copy_from "/tmp/uploaded_file.csv", columns: [:name, :taxon_id, :updated_at, :created_at]

Answer 2

Thanks to @PhilipHallstrom's link, I used COPY FROM STDIN like this:

rc = User.connection.raw_connection
rc.exec("COPY users (name, taxon_id, updated_at, created_at) FROM STDIN")
begin
  until rc.put_copy_data( data )
    $stderr.puts "  waiting for connection to be writable..."
    sleep 0.1
  end
rescue Errno => err
  @errmsg = @errmsg + "%s while reading copy data: %s" % [ err.class.name, err.message ]
  error = true
else
  rc.put_copy_end
  while res = rc.get_result
    if (res.result_status != 1)
      error = true
      @errmsg = @errmsg + "Result of COPY is: %s" % [ res.res_status(res.result_status) ]
    end
  end
end