Seed Dump

Seed Dump is a Rails 4 and 5 plugin that adds a rake task named db:seed:dump.

It allows you to create seed data files from the existing data in your database.

You can also use Seed Dump from the Rails console. See below for usage examples.

Note: if you want to use Seed Dump with Rails 3 or earlier, use version 0.5.3.

Installation

Add it to your Gemfile with:

gem 'seed_dump'

Or install it by hand:

$ gem install seed_dump

Examples

Rake task

Dump all data directly to db/seeds.rb:

  $ rake db:seed:dump

Result:

Product.create!([
  { category_id: 1, description: "Long Sleeve Shirt", name: "Long Sleeve Shirt" },
  { category_id: 3, description: "Plain White Tee Shirt", name: "Plain T-Shirt" }
])
User.create!([
  { password: "123456", username: "test_1" },
  { password: "234567", username: "test_2" }
])

Dump only data from the users table and dump a maximum of 1 record:

$ rake db:seed:dump MODELS=User LIMIT=1

Result:

User.create!([
  { password: "123456", username: "test_1" }
])

Append to db/seeds.rb instead of overwriting it:

rake db:seed:dump APPEND=true

Use another output file instead of db/seeds.rb:

rake db:seed:dump FILE=db/seeds/users.rb

Exclude name and age from the dump:

rake db:seed:dump EXCLUDE=name,age

There are more options that can be set— see below for all of them.

Console

Output a dump of all User records:

irb(main):001:0> puts SeedDump.dump(User)
User.create!([
  { password: "123456", username: "test_1" },
  { password: "234567", username: "test_2" }
])

Write the dump to a file:

irb(main):002:0> SeedDump.dump(User, file: 'db/seeds.rb')

Append the dump to a file:

irb(main):003:0> SeedDump.dump(User, file: 'db/seeds.rb', append: true)

Exclude name and age from the dump:

irb(main):004:0> SeedDump.dump(User, exclude: [:name, :age])

Options are specified as a Hash for the second argument.

In the console, any relation of ActiveRecord rows can be dumped (not individual objects though)

irb(main):001:0> puts SeedDump.dump(User.where(is_admin: false))
User.create!([
  { password: "123456", username: "test_1", is_admin: false },
  { password: "234567", username: "test_2", is_admin: false }
])

Options

Options are common to both the Rake task and the console, except where noted.

append: If set to true, append the data to the file instead of overwriting it. Default: false.

batch_size: Controls the number of records that are written to file at a given time. Default: 1000. If you're running out of memory when dumping, try decreasing this. If things are dumping too slow, trying increasing this.

exclude: Attributes to be excluded from the dump. Pass a comma-separated list to the Rake task (i.e. name,age) and an array on the console (i.e. [:name, :age]). Default: [:id, :created_at, :updated_at].

file: Write to the specified output file. The Rake task default is db/seeds.rb. The console returns the dump as a string by default.

import: If true, output will be in the format needed by the activerecord-import gem, rather than the default format. Default: false.

import_method: Only relevant if import is not used! By default the creation instructions are generated with Model.create!. There will be reasons like validations, speed, etc. why this won't fit the users needs. so with the IMPORT_METHOD an alternative method name (like insert_all! or upsert_all!) can be chosen. Example: rake db:seed:dump IMPORT_METHOD=upsert_all!

limit: Dump no more than this amount of data. Default: no limit. Rake task only. In the console just pass in an ActiveRecord::Relation with the appropriate limit (e.g. SeedDump.dump(User.limit(5))).

conditions: Dump only specific records. In the console just pass in an ActiveRecord::Relation with the appropriate conditions (e.g. SeedDump.dump(User.where(state: :active))).

model[s]: Restrict the dump to the specified comma-separated list of models. Default: all models. If you are using a Rails engine you can dump a specific model by passing "EngineName::ModelName". Rake task only. Example: rake db:seed:dump MODELS="User, Position, Function"

models_exclude: Exclude the specified comma-separated list of models from the dump. Default: no models excluded. Rake task only. Example: rake db:seed:dump MODELS_EXCLUDE="User"