# File lib/active_record/fixtures.rb, line 711 def primary_key_name @primary_key_name ||= model_class && model_class.primary_key end
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:
-
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).
-
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
Public Class Methods
# File lib/active_record/fixtures.rb, line 439 def self.cache_fixtures(connection, fixtures_map) cache_for_connection(connection).update(fixtures_map) end
# File lib/active_record/fixtures.rb, line 423 def self.cache_for_connection(connection) @@all_cached_fixtures[connection] end
# 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
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
# 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
# File lib/active_record/fixtures.rb, line 427 def self.fixture_is_cached?(connection, table_name) cache_for_connection(connection)[table_name] end
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
# 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
# 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
# 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
# File lib/active_record/fixtures.rb, line 419 def self.reset_cache @@all_cached_fixtures.clear end
Public Instance Methods
# File lib/active_record/fixtures.rb, line 593 def [](x) fixtures[x] end
# File lib/active_record/fixtures.rb, line 597 def []=(k,v) fixtures[k] = v end
# File lib/active_record/fixtures.rb, line 601 def each(&block) fixtures.each(&block) end
# File lib/active_record/fixtures.rb, line 605 def size fixtures.size end
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
# 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
# File lib/active_record/fixtures.rb, line 749 def column_names @column_names ||= @connection.columns(@table_name).collect { |c| c.name } end
# 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
# File lib/active_record/fixtures.rb, line 745 def inheritance_column_name @inheritance_column_name ||= model_class && model_class.inheritance_column end
# 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
# 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
# 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
# File lib/active_record/fixtures.rb, line 767 def yaml_file_path(path) "#{path}.yml" end