Added CSV format for fixtures #272 [what-a-day]

git-svn-id: http://svn-commit.rubyonrails.org/rails/trunk@55 5ecf4fe2-1ee6-0310-87b1-e25e094e27de

activerecord/CHANGELOG

 *CVS*
 
+* Added CSV format for fixtures #272 [what-a-day]. (See the new and expanded documentation on fixtures for more information)
+
 * Fixed fixtures using primary key fields called something else than "id" [dave]
 
 * Added proper handling of time fields that are turned into Time objects with the dummy date of 2000/1/1 [HariSeldon]

activerecord/lib/active_record/fixtures.rb

 require 'erb'
 require 'yaml'
+require 'csv'
 require 'active_record/support/class_inheritable_attributes'
 require 'active_record/support/inflector'
 
-# Fixtures are a way of organizing data that you want to test against. You normally have one YAML file with fixture
-# definitions per model. They're just hashes of hashes with the first-level key being the name of fixture (try to keep
-# that name unique across all fixtures in the system for reasons that will follow). The value to that key is a hash
-# where the keys are column names and the values the fixture data you want to insert into it. Example for developers.yml:
+# Fixtures are a way of organizing data that you want to test against; in short, sample data. They come in 3 flavours:
 #
-# david:
-#  id: 1
-#  name: David Heinemeier Hansson
-#  birthday: 1979-10-15
-#  profession: Systems development
+#   1.  YAML fixtures
+#   2.  CSV fixtures
+#   3.  Single-file fixtures
 #
-# steve:
-#  id: 2
-#  name: Steve Ross Kellock
-#  birthday: 1974-09-27
-#  profession: guy with keyboard
+# = YAML fixtures
 #
-# So this YAML file includes two fixtures. T
+# This type of fixture is in YAML format and the preferred default. YAML is a file format which describes data structures
+# in a non-verbose, humanly-readable format. It ships with Ruby 1.8.1+.
 #
-# Now when we call <tt>@developers = Fixtures.create_fixtures(".", "developers")</tt> both developers will get inserted into 
-# the "developers" table through the active Active Record connection (that must be setup before-hand). And we can now query 
-# the fixture data through the <tt>@developers</tt> hash, so <tt>@developers["david"]["name"]</tt> will return 
-# <tt>"David Heinemeier Hansson"</tt> and <tt>@developers["david"]["birthday"]</tt> will return <tt>Date.new(1979, 10, 15)</tt>.
+# Unlike single-file fixtures, YAML fixtures are stored in a single file per model, which is place in the directory appointed
+# by <tt>Test::Unit::TestCase.fixture_path=(path)</tt> (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 (Rails example:
+# "<your-rails-app>/test/fixtures/web_sites.yml"). The format of a YAML fixture file looks like this:
 #
-# In addition to getting the raw data, we can also get the Developer object by doing @developers["david"].find. This can then 
-# be used for comparison in a unit test. Something like:
+#   rubyonrails:
+#     id: 1
+#     name: Ruby on Rails
+#     url: http://www.rubyonrails.org
 #
+#   google:
+#     id: 2
+#     name: Google
+#     url: http://www.google.com
+#
+# This YAML 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.  
+#
+# = CSV fixtures
+#
+# Fixtures can also be kept in the in the Comma Separated Value format. Akin to YAML fixtures, CSV fixtures are stored
+# in a single file, but, instead end with the .csv file extension (Rails example: "<your-rails-app>/test/fixtures/web_sites.csv")
+#
+# The format of this tye of fixture file is much more compact than the others, but also a little harder to read by us
+# humans.  The first line of the CSV file is a comma-separated list of field names.  The rest of the file is then comprised
+# of the actual data (1 per line).  Here's an example:
+#
+#   id, name, url
+#   1, Ruby On Rails, http://www.rubyonrails.org
+#   2, Google, http://www.google.com
+#
+# Should you have a piece of data with a comma character in it, you can place double quotes around that value.  If you
+# need to use a double quote character, you must escape it with another double quote.
+#
+# Another unique attribute of the CSV fixture is that it has *no* fixture name like the other two formats.  Instead, the
+# fixture names are automatically generated by deriving the class name of the fixture file and adding an incrementing 
+# number to the end.  In our example, the 1st fixture would be called "web_site_1" and the 2nd one would be called
+# "web_site_2".
+#
+# Most databases and spreadsheets support exporting to CSV format, so this is a great format for you to choose if you 
+# have existing data somewhere already.
+# 
+# = Single-file fixtures 
+#
+# This type of fixtures was the original format for Active Record that has since been deprecated in favor of the YAML and CSV formats.
+# Fixtures for this format are created by placing text files in a sub-directory (with the name of the model) to the directory 
+# appointed by <tt>Test::Unit::TestCase.fixture_path=(path)</tt> (this is automatically configured for Rails, so you can just
+# put your files in <your-rails-app>/test/fixtures/<your-model-name>/ -- like <your-rails-app>/test/fixtures/web_sites/ for the WebSite
+# model).
+#
+# Each text file placed in this directory represents a "record".  Usually these types of fixtures are named without
+# extensions, but if you are on a Windows machine, you might consider adding .txt as the extension.  Here's what the
+# above example might look like:
+#
+#   web_sites/google
+#   web_sites/yahoo.txt
+#   web_sites/ruby-on-rails
+#
+# The file format of a standard fixture is simple.  Each line is a property (or column in db speak) and has the syntax
+# of "name => value".  Here's an example of the ruby-on-rails fixture above:
+#
+#   id => 1
+#   name => Ruby on Rails
+#   url => http://www.rubyonrails.org
+#
+# = Using Fixtures
+#
+# 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 lets take a look at a sample unit test found:
+#
+#   require 'web_site'
+#
+#   class WebSiteTest < Test::Unit::TestCase
+#     def test_web_site_count
+#       assert_equal 2, WebSite.count
+#     end 
+#   end
+#  
+# As it stands, unless we pre-load the web_site table in our database with two records, this test will fail.  Here's the 
+# easiest way to add fixtures to the database:
+#
+#   ...
+#   class WebSiteTest < Test::Unit::TestCase
+#     fixtures :web_sites # add more by separating the symbols with commas
+#   ...
+#  
+# By adding a "fixtures" method to the test case and passing it a list of symbols (only one is shown here tho), we trigger
+# the testing environment to automatically load the appropriate fixtures into the database before each test, and 
+# automatically delete them after each test.
+#
+# In addition to being available in the database, the fixtures are also loaded into a hash stored in an instance variable
+# of the test case.  It is named after the symbol... so, in our example, there would be a hash available called
+# @web_sites.  This is where the "fixture name" comes into play.
+#
+# On top of that, each record is automatically "found" (using Model.find(id)) and placed in the instance variable of its name.
+# So for the YAML fixtures, we'd get @rubyonrails and @google, which could be interrogated using regular Active Record semantics:
+#
+#   # test if the object created from the fixture data has the same attributes as the data itself
 #   def test_find
-#     assert_equal @developers["david"]["name"], @developers["david"].find.name
+#     assert_equal @web_sites["rubyonrails"]["name"], @rubyonrails.name
 #   end
 #
-# Comparing that the data we have on the name is also what the object returns when we ask for it.
+# As seen above, the data hash created from the YAML fixtures would have @web_sites["rubyonrails"]["url"] return
+# "http://www.rubyonrails.org" and @web_sites["google"]["name"] would return "Google". The same fixtures, but loaded
+# from a CSV fixture file would be accessible via @web_sites["web_site_1"]["name"] == "Ruby on Rails" and have the individual
+# fixtures available as instance variables @web_site_1 and @web_site_2.
 #
-# == Automatic fixture setup and instance variable availability
+# = Dynamic fixtures with ERb
 #
-# Fixtures can also be automatically instantiated in instance variables relating to their names using the following style:
+# 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 or CSV fixtures to create a bunch of fixtures for load testing, like:
 #
-#   class FixturesTest < Test::Unit::TestCase
-#     fixtures :developers # you can add more with comma separation
+# <% for i in 1..1000 %>
+# fix_<%= i %>:
+#   id: <%= i %>
+#   name: guy_<%= 1 %>
+# <% end %>
 #
-#     def test_developers
-#       assert_equal 3, @developers.size # the container for all the fixtures is automatically set
-#       assert_kind_of Developer, @david # works like @developers["david"].find
-#       assert_equal "David Heinemeier Hansson", @david.name
-#     end
-#   end
+# This will create 1000 YAML 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.
 class Fixtures < Hash
   def self.instantiate_fixtures(object, fixtures_directory, *table_names)
     [ create_fixtures(fixtures_directory, *table_names) ].flatten.each_with_index do |fixtures, idx|
@@ -68,8 +159,8 @@ def self.create_fixtures(fixtures_directory, *table_names)
         fixtures = table_names.flatten.map do |table_name|
           Fixtures.new(connection, table_name.to_s, File.join(fixtures_directory, table_name.to_s))
         end
-        fixtures.reverse.each{ |fixture| fixture.delete_existing_fixtures }
-        fixtures.each{ |fixture| fixture.insert_fixtures }
+        fixtures.reverse.each { |fixture| fixture.delete_existing_fixtures }
+        fixtures.each { |fixture| fixture.insert_fixtures }
       end
       return fixtures.size > 1 ? fixtures : fixtures.first
     ensure
@@ -77,7 +168,7 @@ def self.create_fixtures(fixtures_directory, *table_names)
     end
   end
 
-  def initialize(connection, table_name, fixture_path, file_filter = /^\.|CVS|\.yml/)
+  def initialize(connection, table_name, fixture_path, file_filter = /^\.|CVS|\.yml|\.csv/)
     @connection, @table_name, @fixture_path, @file_filter = connection, table_name, fixture_path, file_filter
     @class_name = Inflector.classify(@table_name)
 
@@ -97,10 +188,22 @@ def insert_fixtures
   private
     def read_fixture_files
       if File.exists?(yaml_file_path)
+        # YAML fixtures
         YAML::load(erb_render(IO.read(yaml_file_path))).each do |name, data|
           self[name] = Fixture.new(data, @class_name)
         end
+      elsif File.exists?(csv_file_path)
+        # CSV fixtures
+        reader = CSV::Reader.create(erb_render(IO.read(csv_file_path)))
+        header = reader.shift
+        i = 0
+        reader.each do |row|
+          data = {}
+          row.each_with_index { |cell, j| data[header[j].to_s.strip] = cell.to_s.strip }
+          self["#{Inflector::underscore(@class_name)}_#{i+=1}"]= Fixture.new(data, @class_name)
+        end
       else
+        # Standard fixtures
         Dir.entries(@fixture_path).each do |file| 
           self[file] = Fixture.new(File.join(@fixture_path, file), @class_name) unless file =~ @file_filter
         end
@@ -110,6 +213,10 @@ def read_fixture_files
     def yaml_file_path
       @fixture_path + ".yml"
     end
+
+    def csv_file_path
+      @fixture_path + ".csv"
+    end
     
     def yaml_fixtures_key(path)
       File.basename(@fixture_path).split(".").first