ActiveRecordCSVImporter

ActiveRecordCSVImporter is a modified version CSVImporter, which uses activerecord-import to speed up processing.

The key difference with CSVImporter is the removal of callback support, since that is incompatible with bulk inserts. Additional config options are available instead to deal with batching and index conflicts.

It is compatible with ActiveRecord and any Databases supported by activerecord-import.

Define your CSVImporter:

class ImportUserCSV
  include ActiveRecordCSVImporter

  model User # an active record like model

  column :email, to: ->(email) { email.downcase }, required: true
  column :first_name, as: [ /first.?name/i, /pr(é|e)nom/i ]
  column :last_name,  as: [ /last.?name/i, "nom" ]

  on_duplicate_key(
    on_duplicate_key_update: {
      conflict_target: [:email], columns: [:first_name, :last_name]
    }
  )

  batch_size 500

  each_batch { |report|
    puts report.total_count
    puts report.completed_count
    puts report.failed_rows
  }
end

Run the import:

import = ImportUserCSV.new(file: my_file)

import.valid_header?  # => false
import.report.message # => "The following columns are required: email"

# Assuming the header was valid, let's run the import!

import.run!
import.report.sucess? # => true
import.report.message  # => "Import completed. 4 created, 2 updated, 1 failed to update"

Add this line to your application's Gemfile:

gem 'activerecord_csv_importer'

And then execute:

$ bundle

Or install it yourself as:

$ gem activerecord_csv_importer

Create a class and include CSVImporter.

class ImportUserCSV
  include CSVImporter
end

The model is can be a active record model.

class ImportUserCSV
  include CSVImporter

  model User
end

It can also be a relation which is handy to preset attributes:

class User
  scope :pending, -> { where(status: 'pending') }
end

class ImportUserCSV
  include CSVImporter

  model User.pending
end

You can change the configuration at runtime to scope down to associated records.

class Team
  has_many :users
end

team = Team.find(1)

ImportUserCSV.new(path: "tmp/my_file.csv") do
  model team.users
end

This is where the fun begins.

class ImportUserCSV
  include CSVImporter

  model User

  column :email
end

This will map the column named email to the email attribute. By default, we downcase and strip the columns so it will work with a column spelled " EMail ".

Now, email could also be spelled "e-mail", or "mail", or even "courriel" (oh, canada). Let's give it a couple of aliases then:

  column :email, as: [/e.?mail/i, "courriel"]

Nice, emails should be downcased though, so let's do this.

  column :email, as: [/e.?mail/i, "courriel"], to: ->(email) { email.downcase }

Now, what if the user does not provide the email column? It's not worth running the import, we should just reject the CSV file right away. That's easy:

class ImportUserCSV
  include CSVImporter

  model User

  column :email, required: true
end

import = ImportUserCSV.new(content: "name\nbob")
import.valid_header? # => false
import.report.status # => :invalid_header
import.report.message # => "The following columns are required: 'email'"

You usually want to prevent duplicates when importing a CSV file. activerecord-import provides ON CONFLICT support for MySQL, SQLite (IGNORE only), and PostgreSQL. See the activerecord-import wiki for detailed syntax.

NOTE: If you have set up a unique index on a field and not set an appropriate ON CONFLICT resolution, activerecord_csv_import will raise an exception on the first duplicate insert.

class ImportUserCSV
  include CSVImporter

  model User

  column :email, to: ->(email) { email.downcase }
  column :first_name
  column :last_name

  on_duplicate_key(
    on_duplicate_key_update: {
      conflict_target: [:email], columns: [:first_name, :last_name]
    }
  )
end

You are now done defining your importer, let's run it!

You can import from a file, path or just the CSV content. Please note that we currently load the entire file in memory. Feel free to contribute if you need to support CSV files with millions of lines! :)

import = ImportUserCSV.new(file: my_file)
import = ImportUserCSV.new(path: "tmp/new_users.csv")
import = ImportUserCSV.new(content: "email,name\nbob@example.com,bob")

It is often needed to change the configuration at runtime, that's quite easy:

team = Team.find(1)
import = ImportUserCSV.new(file: my_file) do
  model team.users
end

The number of rows to insert in the bulk query can be set by setting batch_size (default 500)

The each batch callback is triggered after each batch is processed and returns the report object for the full process. This is generally useful when you want to display progress.

progress_bar = ProgressBar.new

UserImport.new(file: my_file) do
  each_batch do |report|
    progress_bar.increment(report.progress_percentage)
  end
end

Other available methods are:

• total_count
• completed_count
• failed_rows

On a web application, as soon as a CSV file is uploaded, you can check if it has the required columns. This is handy to fail early an provide the user with a meaningful error message right away.

import = ImportUserCSV.new(file: params[:csv_file])
import.valid_header? # => false
import.report.message # => "The following columns are required: "email""

import = ImportUserCSV.new(file: params[:csv_file])
import.run!
import.report.message  # => "Import completed."

You can get your hands dirty and fetch the errored rows and the associated error message:

import.report.invalid_rows.map { |row| [row.model.email, row.errors] }
  # => [ ['INVALID_EMAIL', 'first_name', 'last_name', { 'email' => 'is not an email' }] ]

We do our best to map the errors back to the original column name. So with the following definition:

  column :email, as: /e.?mail/i

and csv:

E-Mail,name
INVALID_EMAIL,bob

The error returned should be: { "E-Mail" => "is invalid" }

You can handle exotic quote chars with the quote_char option.

email,name
bob@example.com,'bob "elvis" wilson'

import = ImportUserCSV.new(content: csv_content)
import.run!
import.report.status
  # => :invalid_csv_file
import.report.messages
  # => CSV::MalformedCSVError: Illegal quoting in line 2.

Let's provide a valid quote char:

import = ImportUserCSV.new(content: csv_content, quote_char: "'")
import.run!
  # => [ ["bob@example.com", "bob \"elvis\" wilson"] ]

You can handle exotic encodings with the encoding option.

ImportUserCSV.new(content: "メール,氏名".encode('SJIS'), encoding: 'UTF-8')

• Add ability to configure activerecord-import validate: Bool option.
• Allow setting a default attribute on columns.

After checking out the repo, run bin/setup to install dependencies. Then, run bin/console for an interactive prompt that will allow you to experiment.

To install this gem onto your local machine, run bundle exec rake install. To release a new version, update the version number in version.rb, and then run bundle exec rake release to create a git tag for the version, push git commits and tags, and push the .gem file to rubygems.org.

Bug reports and pull requests are welcome on GitHub at https://github.com/desheikh/activerecord_csv_importer.

The gem is available as open source under the terms of the MIT License.