class ActiveRecord::FixtureSet - activerecord-4.2.4 Documentation

# class ActiveRecord::FixtureSet

Fixtures are a way of organizing data that you want to test against; in short, sample data.

They are stored in YAML files, one file per model, which are placed in the directory appointed by `ActiveSupport::TestCase.fixture_path=(path)` (this is automatically configured for Rails, so you can just put your files in `<your-rails-app>/test/fixtures/`). The fixture file ends with the `.yml` file extension, for example: `<your-rails-app>/test/fixtures/web_sites.yml`).

The format of a fixture file looks like this:

    rubyonrails:
      id: 1
      name: Ruby on Rails
      url: http://www.rubyonrails.org

    google:
      id: 2
      name: Google
      url: http://www.google.com

This fixture file includes two fixtures. Each YAML fixture (ie. record) is given a name and is followed by an indented list of key/value pairs in the “key: value” format. Records are separated by a blank line for your viewing pleasure.

Note: Fixtures are unordered. If you want ordered fixtures, use the omap YAML type. See yaml.org/type/omap.html for the specification. You will need ordered fixtures when you have foreign key constraints on keys in the same table. This is commonly needed for tree structures. Example:

    --- !omap
    - parent:
        id:         1
        parent_id:  NULL
        title:      Parent
    - child:
        id:         2
        parent_id:  1
        title:      Child

# Using Fixtures in Test Cases¶ ↑

Since fixtures are a testing construct, we use them in our unit and functional tests. There are two ways to use the fixtures, but first let's take a look at a sample unit test:

    require 'test_helper'

    class WebSiteTest < ActiveSupport::TestCase
      test "web_site_count" do
        assert_equal 2, WebSite.count
      end
    end

By default, `test_helper.rb` will load all of your fixtures into your test database, so this test will succeed.

The testing environment will automatically load the all fixtures into the database before each test. To ensure consistent data, the environment deletes the fixtures before running the load.

In addition to being available in the database, the fixture's data may also be accessed by using a special dynamic method, which has the same name as the model, and accepts the name of the fixture to instantiate:

    test "find" do
      assert_equal "Ruby on Rails", web_sites(:rubyonrails).name
    end

Alternatively, you may enable auto-instantiation of the fixture data. For instance, take the following tests:

    test "find_alt_method_1" do
      assert_equal "Ruby on Rails", @web_sites['rubyonrails']['name']
    end

    test "find_alt_method_2" do
      assert_equal "Ruby on Rails", @rubyonrails.name
    end

In order to use these methods to access fixtured data within your testcases, you must specify one of the following in your `ActiveSupport::TestCase`-derived class:

- to fully enable instantiated fixtures (enable alternate methods #1 and #2 above)

      self.use_instantiated_fixtures = true

- create only the hash for the fixtures, do not 'find' each instance (enable alternate method #1 only)

      self.use_instantiated_fixtures = :no_instances

Using either of these alternate methods incurs a performance hit, as the fixtured data must be fully traversed in the database to create the fixture hash and/or instance variables. This is expensive for large sets of fixtured data.

# Dynamic fixtures with ERB¶ ↑

Some times you don't care about the content of the fixtures as much as you care about the volume. In these cases, you can mix ERB in with your YAML fixtures to create a bunch of fixtures for load testing, like:

    <% 1.upto(1000) do |i| %>
    fix_<%= i %>:
      id: <%= i %>
      name: guy_<%= 1 %>
    <% end %>

This will create 1000 very simple fixtures.

Using ERB, you can also inject dynamic values into your fixtures with inserts like `<%= Date.today.strftime("%Y-%m-%d") %>`. This is however a feature to be used with some caution. The point of fixtures are that they're stable units of predictable sample data. If you feel that you need to inject dynamic values, then perhaps you should reexamine whether your application is properly testable. Hence, dynamic values in fixtures are to be considered a code smell.

Helper methods defined in a fixture will not be available in other fixtures, to prevent against unwanted inter-test dependencies. Methods used by multiple fixtures should be defined in a module that is included in `ActiveRecord::FixtureSet.context_class`.

- define a helper method in `test_helper.rb`

      module FixtureFileHelpers
        def file_sha(path)
          Digest::SHA2.hexdigest(File.read(Rails.root.join('test/fixtures', path)))
        end
      end
      ActiveRecord::FixtureSet.context_class.send :include, FixtureFileHelpers

- use the helper method in a fixture

      photo:
        name: kitten.png
        sha: <%= file_sha 'files/kitten.png' %>

# Transactional Fixtures¶ ↑

Test cases can use begin+rollback to isolate their changes to the database instead of having to delete+insert for every test case.

    class FooTest < ActiveSupport::TestCase
      self.use_transactional_fixtures = true

      test "godzilla" do
        assert !Foo.all.empty?
        Foo.destroy_all
        assert Foo.all.empty?
      end

      test "godzilla aftermath" do
        assert !Foo.all.empty?
      end
    end

If you preload your test database with all fixture data (probably in the rake task) and use transactional fixtures, then you may omit all fixtures declarations in your test cases since all the data's already there and every case rolls back its changes.

In order to use instantiated fixtures with preloaded data, set `self.pre_loaded_fixtures` to true. This will provide access to fixture data for every table that has been loaded through fixtures (depending on the value of `use_instantiated_fixtures`).

When not to use transactional fixtures:

1. You're testing whether a transaction works correctly. Nested transactions don't commit until all parent transactions commit, particularly, the fixtures transaction which is begun in setup and rolled back in teardown. Thus, you won't be able to verify the results of your transaction until Active Record supports nested transactions or savepoints (in progress).

2. Your database does not support transactions. Every Active Record database supports transactions except MySQL MyISAM. Use InnoDB, MaxDB, or NDB instead.

# Advanced Fixtures¶ ↑

Fixtures that don't specify an ID get some extra features:

- Stable, autogenerated IDs

- Label references for associations (belongs_to, has_one, has_many)

- HABTM associations as inline lists

There are some more advanced features available even if the id is specified:

- Autofilled timestamp columns

- Fixture label interpolation

- Support for YAML defaults

## Stable, Autogenerated IDs¶ ↑

Here, have a monkey fixture:

    george:
      id: 1
      name: George the Monkey

    reginald:
      id: 2
      name: Reginald the Pirate

Each of these fixtures has two unique identifiers: one for the database and one for the humans. Why don't we generate the primary key instead? Hashing each fixture's label yields a consistent ID:

    george: # generated id: 503576764
      name: George the Monkey

    reginald: # generated id: 324201669
      name: Reginald the Pirate

Active Record looks at the fixture's model class, discovers the correct primary key, and generates it right before inserting the fixture into the database.

The generated ID for a given label is constant, so we can discover any fixture's ID without loading anything, as long as we know the label.

## Label references for associations (belongs_to, has_one, has_many)¶ ↑

Specifying foreign keys in fixtures can be very fragile, not to mention difficult to read. Since Active Record can figure out the ID of any fixture from its label, you can specify FK's by label instead of ID.

### belongs_to¶ ↑

Let's break out some more monkeys and pirates.

    ### in pirates.yml

    reginald:
      id: 1
      name: Reginald the Pirate
      monkey_id: 1

    ### in monkeys.yml

    george:
      id: 1
      name: George the Monkey
      pirate_id: 1

Add a few more monkeys and pirates and break this into multiple files, and it gets pretty hard to keep track of what's going on. Let's use labels instead of IDs:

    ### in pirates.yml

    reginald:
      name: Reginald the Pirate
      monkey: george

    ### in monkeys.yml

    george:
      name: George the Monkey
      pirate: reginald

Pow! All is made clear. Active Record reflects on the fixture's model class, finds all the `belongs_to` associations, and allows you to specify a target label for the association (monkey: george) rather than a target id for the FK (`monkey_id: 1`).

#### Polymorphic belongs_to¶ ↑

Supporting polymorphic relationships is a little bit more complicated, since Active Record needs to know what type your association is pointing at. Something like this should look familiar:

    ### in fruit.rb

    belongs_to :eater, polymorphic: true

    ### in fruits.yml

    apple:
      id: 1
      name: apple
      eater_id: 1
      eater_type: Monkey

Can we do better? You bet!

    apple:
      eater: george (Monkey)

Just provide the polymorphic target type and Active Record will take care of the rest.

### has_and_belongs_to_many¶ ↑

Time to give our monkey some fruit.

    ### in monkeys.yml

    george:
      id: 1
      name: George the Monkey

    ### in fruits.yml

    apple:
      id: 1
      name: apple

    orange:
      id: 2
      name: orange

    grape:
      id: 3
      name: grape

    ### in fruits_monkeys.yml

    apple_george:
      fruit_id: 1
      monkey_id: 1

    orange_george:
      fruit_id: 2
      monkey_id: 1

    grape_george:
      fruit_id: 3
      monkey_id: 1

Let's make the HABTM fixture go away.

    ### in monkeys.yml

    george:
      id: 1
      name: George the Monkey
      fruits: apple, orange, grape

    ### in fruits.yml

    apple:
      name: apple

    orange:
      name: orange

    grape:
      name: grape

Zap! No more fruits_monkeys.yml file. We've specified the list of fruits on George's fixture, but we could've just as easily specified a list of monkeys on each fruit. As with `belongs_to`, Active Record reflects on the fixture's model class and discovers the `has_and_belongs_to_many` associations.

## Autofilled Timestamp Columns¶ ↑

If your table/model specifies any of Active Record's standard timestamp columns (`created_at`, `created_on`, `updated_at`, `updated_on`), they will automatically be set to `Time.now`.

If you've set specific values, they'll be left alone.

## Fixture label interpolation¶ ↑

The label of the current fixture is always available as a column value:

    geeksomnia:
      name: Geeksomnia's Account
      subdomain: $LABEL
      email: $LABEL@email.com

Also, sometimes (like when porting older join table fixtures) you'll need to be able to get a hold of the identifier for a given label. ERB to the rescue:

    george_reginald:
      monkey_id: <%= ActiveRecord::FixtureSet.identify(:reginald) %>
      pirate_id: <%= ActiveRecord::FixtureSet.identify(:george) %>

## Support for YAML defaults¶ ↑

You can set and reuse defaults in your fixtures YAML file. This is the same technique used in the `database.yml` file to specify defaults:

    DEFAULTS: &DEFAULTS
      created_on: <%= 3.weeks.ago.to_s(:db) %>

    first:
      name: Smurf
      <<: *DEFAULTS

    second:
      name: Fraggle
      <<: *DEFAULTS

Any fixture labeled “DEFAULTS” is safely ignored.

### Constants

MAX_ID

### Attributes

config[R]
fixtures[R]
model_class[R]
name[R]
table_name[R]

### Public Class Methods

cache_fixtures(connection, fixtures_map) click to toggle source

    # File lib/active_record/fixtures.rb, line 439
    def self.cache_fixtures(connection, fixtures_map)
      cache_for_connection(connection).update(fixtures_map)
    end

cache_for_connection(connection) click to toggle source

    # File lib/active_record/fixtures.rb, line 423
    def self.cache_for_connection(connection)
      @@all_cached_fixtures[connection]
    end

cached_fixtures(connection, keys_to_fetch = nil) click to toggle source

    # File lib/active_record/fixtures.rb, line 431
    def self.cached_fixtures(connection, keys_to_fetch = nil)
      if keys_to_fetch
        cache_for_connection(connection).values_at(*keys_to_fetch)
      else
        cache_for_connection(connection).values
      end
    end

context_class() click to toggle source

Superclass for the evaluation contexts used by ERB fixtures.

    # File lib/active_record/fixtures.rb, line 562
    def self.context_class
      @context_class ||= Class.new
    end

create_fixtures(fixtures_directory, fixture_set_names, class_names = {}, config = ActiveRecord::Base) { |: connection| ... } click to toggle source

    # File lib/active_record/fixtures.rb, line 496
    def self.create_fixtures(fixtures_directory, fixture_set_names, class_names = {}, config = ActiveRecord::Base)
      fixture_set_names = Array(fixture_set_names).map(&:to_s)
      class_names = ClassCache.new class_names, config

      # FIXME: Apparently JK uses this.
      connection = block_given? ? yield : ActiveRecord::Base.connection

      files_to_read = fixture_set_names.reject { |fs_name|
        fixture_is_cached?(connection, fs_name)
      }

      unless files_to_read.empty?
        connection.disable_referential_integrity do
          fixtures_map = {}

          fixture_sets = files_to_read.map do |fs_name|
            klass = class_names[fs_name]
            conn = klass ? klass.connection : connection
            fixtures_map[fs_name] = new( # ActiveRecord::FixtureSet.new
              conn,
              fs_name,
              klass,
              ::File.join(fixtures_directory, fs_name))
          end

          update_all_loaded_fixtures fixtures_map

          connection.transaction(:requires_new => true) do
            fixture_sets.each do |fs|
              conn = fs.model_class.respond_to?(:connection) ? fs.model_class.connection : connection
              table_rows = fs.table_rows

              table_rows.each_key do |table|
                conn.delete "DELETE FROM #{conn.quote_table_name(table)}", 'Fixture Delete'
              end

              table_rows.each do |fixture_set_name, rows|
                rows.each do |row|
                  conn.insert_fixture(row, fixture_set_name)
                end
              end

              # Cap primary key sequences to max(pk).
              if conn.respond_to?(:reset_pk_sequence!)
                conn.reset_pk_sequence!(fs.table_name)
              end
            end
          end

          cache_fixtures(connection, fixtures_map)
        end
      end
      cached_fixtures(connection, fixture_set_names)
    end

fixture_is_cached?(connection, table_name) click to toggle source

    # File lib/active_record/fixtures.rb, line 427
    def self.fixture_is_cached?(connection, table_name)
      cache_for_connection(connection)[table_name]
    end

identify(label, column_type = :integer) click to toggle source

Returns a consistent, platform-independent identifier for `label`. Integer identifiers are values less than 2^30. UUIDs are RFC 4122 version 5 SHA-1 hashes.

    # File lib/active_record/fixtures.rb, line 553
    def self.identify(label, column_type = :integer)
      if column_type == :uuid
        Digest::UUID.uuid_v5(Digest::UUID::OID_NAMESPACE, label.to_s)
      else
        Zlib.crc32(label.to_s) % MAX_ID
      end
    end

instantiate_all_loaded_fixtures(object, load_instances = true) click to toggle source

    # File lib/active_record/fixtures.rb, line 455
    def self.instantiate_all_loaded_fixtures(object, load_instances = true)
      all_loaded_fixtures.each_value do |fixture_set|
        instantiate_fixtures(object, fixture_set, load_instances)
      end
    end

instantiate_fixtures(object, fixture_set, load_instances = true) click to toggle source

    # File lib/active_record/fixtures.rb, line 443
    def self.instantiate_fixtures(object, fixture_set, load_instances = true)
      if load_instances
        fixture_set.each do |fixture_name, fixture|
          begin
            object.instance_variable_set "@#{fixture_name}", fixture.find
          rescue FixtureClassNotFound
            nil
          end
        end
      end
    end

new(connection, name, class_name, path, config = ActiveRecord::Base) click to toggle source

    # File lib/active_record/fixtures.rb, line 572
    def initialize(connection, name, class_name, path, config = ActiveRecord::Base)
      @name     = name
      @path     = path
      @config   = config
      @model_class = nil

      if class_name.is_a?(Class) # TODO: Should be an AR::Base type class, or any?
        @model_class = class_name
      else
        @model_class = class_name.safe_constantize if class_name
      end

      @connection  = connection

      @table_name = ( model_class.respond_to?(:table_name) ?
                      model_class.table_name :
                      self.class.default_fixture_table_name(name, config) )

      @fixtures = read_fixture_files path, @model_class
    end

reset_cache() click to toggle source

    # File lib/active_record/fixtures.rb, line 419
    def self.reset_cache
      @@all_cached_fixtures.clear
    end

### Public Instance Methods

[](x) click to toggle source

    # File lib/active_record/fixtures.rb, line 593
    def [](x)
      fixtures[x]
    end

[]=(k,v) click to toggle source

    # File lib/active_record/fixtures.rb, line 597
    def []=(k,v)
      fixtures[k] = v
    end

each(&block) click to toggle source

    # File lib/active_record/fixtures.rb, line 601
    def each(&block)
      fixtures.each(&block)
    end

size() click to toggle source

    # File lib/active_record/fixtures.rb, line 605
    def size
      fixtures.size
    end

table_rows() click to toggle source

Returns a hash of rows to be inserted. The key is the table, the value is a list of rows to insert to that table.

    # File lib/active_record/fixtures.rb, line 611
    def table_rows
      now = config.default_timezone == :utc ? Time.now.utc : Time.now
      now = now.to_s(:db)

      # allow a standard key to be used for doing defaults in YAML
      fixtures.delete('DEFAULTS')

      # track any join tables we need to insert later
      rows = Hash.new { |h,table| h[table] = [] }

      rows[table_name] = fixtures.map do |label, fixture|
        row = fixture.to_hash

        if model_class
          # fill in timestamp columns if they aren't specified and the model is set to record_timestamps
          if model_class.record_timestamps
            timestamp_column_names.each do |c_name|
              row[c_name] = now unless row.key?(c_name)
            end
          end

          # interpolate the fixture label
          row.each do |key, value|
            row[key] = value.gsub("$LABEL", label.to_s) if value.is_a?(String)
          end

          # generate a primary key if necessary
          if has_primary_key_column? && !row.include?(primary_key_name)
            row[primary_key_name] = ActiveRecord::FixtureSet.identify(label, primary_key_type)
          end

          # If STI is used, find the correct subclass for association reflection
          reflection_class =
            if row.include?(inheritance_column_name)
              row[inheritance_column_name].constantize rescue model_class
            else
              model_class
            end

          reflection_class._reflections.each_value do |association|
            case association.macro
            when :belongs_to
              # Do not replace association name with association foreign key if they are named the same
              fk_name = (association.options[:foreign_key] || "#{association.name}_id").to_s

              if association.name.to_s != fk_name && value = row.delete(association.name.to_s)
                if association.polymorphic? && value.sub!(/\s*\(([^\)]*)\)\s*$/, "")
                  # support polymorphic belongs_to as "label (Type)"
                  row[association.foreign_type] = $1
                end

                fk_type = reflection_class.columns_hash[fk_name].type
                row[fk_name] = ActiveRecord::FixtureSet.identify(value, fk_type)
              end
            when :has_many
              if association.options[:through]
                add_join_records(rows, row, HasManyThroughProxy.new(association))
              end
            end
          end
        end

        row
      end
      rows
    end

### Private Instance Methods

add_join_records(rows, row, association) click to toggle source

    # File lib/active_record/fixtures.rb, line 719
    def add_join_records(rows, row, association)
      # This is the case when the join table has no fixtures file
      if (targets = row.delete(association.name.to_s))
        table_name  = association.join_table
        column_type = association.primary_key_type
        lhs_key     = association.lhs_key
        rhs_key     = association.rhs_key

        targets = targets.is_a?(Array) ? targets : targets.split(/\s*,\s*/)
        rows[table_name].concat targets.map { |target|
          { lhs_key => row[primary_key_name],
            rhs_key => ActiveRecord::FixtureSet.identify(target, column_type) }
        }
      end
    end

column_names() click to toggle source

    # File lib/active_record/fixtures.rb, line 749
    def column_names
      @column_names ||= @connection.columns(@table_name).collect { |c| c.name }
    end

has_primary_key_column?() click to toggle source

    # File lib/active_record/fixtures.rb, line 735
    def has_primary_key_column?
      @has_primary_key_column ||= primary_key_name &&
        model_class.columns.any? { |c| c.name == primary_key_name }
    end

inheritance_column_name() click to toggle source

    # File lib/active_record/fixtures.rb, line 745
    def inheritance_column_name
      @inheritance_column_name ||= model_class && model_class.inheritance_column
    end

primary_key_name() click to toggle source

    # File lib/active_record/fixtures.rb, line 711
    def primary_key_name
      @primary_key_name ||= model_class && model_class.primary_key
    end

primary_key_type() click to toggle source

    # File lib/active_record/fixtures.rb, line 715
    def primary_key_type
      @primary_key_type ||= model_class && model_class.column_types[model_class.primary_key].type
    end

read_fixture_files(path, model_class) click to toggle source

    # File lib/active_record/fixtures.rb, line 753
    def read_fixture_files(path, model_class)
      yaml_files = Dir["#{path}/{**,*}/*.yml"].select { |f|
        ::File.file?(f)
      } + [yaml_file_path(path)]

      yaml_files.each_with_object({}) do |file, fixtures|
        FixtureSet::File.open(file) do |fh|
          fh.each do |fixture_name, row|
            fixtures[fixture_name] = ActiveRecord::Fixture.new(row, model_class)
          end
        end
      end
    end

timestamp_column_names() click to toggle source

    # File lib/active_record/fixtures.rb, line 740
    def timestamp_column_names
      @timestamp_column_names ||=
        %w(created_at created_on updated_at updated_on) & column_names
    end

yaml_file_path(path) click to toggle source

    # File lib/active_record/fixtures.rb, line 767
    def yaml_file_path(path)
      "#{path}.yml"
    end