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Added a better exception for when a type column is used in a table wi…

…thout the intention of triggering single-table inheritance. Added that single-table inheritance will only kick in if the inheritance_column (by default "type") is present. Otherwise, inheritance wont have any magic side effects

git-svn-id: http://svn-commit.rubyonrails.org/rails/trunk@149 5ecf4fe2-1ee6-0310-87b1-e25e094e27de
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1 parent 317f13c commit 605bc77533cf3b6700e91eda8994cdf6b82341cc @dhh dhh committed Dec 14, 2004
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10 activerecord/CHANGELOG
@@ -1,5 +1,15 @@
*CVS*
+* Added a better exception for when a type column is used in a table without the intention of triggering single-table inheritance. Example:
+
+ ActiveRecord::SubclassNotFound: The single-table inheritance mechanism failed to locate the subclass: 'bad_class!'.
+ This error is raised because the column 'type' is reserved for storing the class in case of inheritance.
+ Please rename this column if you didn't intend it to be used for storing the inheritance class or
+ overwrite Company.inheritance_column to use another column for that information.
+
+* Added that single-table inheritance will only kick in if the inheritance_column (by default "type") is present. Otherwise, inheritance won't
+ have any magic side effects.
+
* Added the possibility of marking fields as being in error without adding a message (using nil) to it that'll get displayed wth full_messages #208 [mjobin]
* Fixed Base.errors to be indifferent as to whether strings or symbols are used. Examples:
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4 activerecord/lib/active_record/associations.rb
@@ -581,7 +581,9 @@ def #{method_prefix + collection_name}(attributes = nil)
end
def require_association_class(class_name)
- begin
+ return unless class_name
+
+ begin
require_association(Inflector.underscore(class_name))
rescue LoadError
# Failed to load the associated class -- let's hope the developer is doing the requiring himself.
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19 activerecord/lib/active_record/base.rb
@@ -6,6 +6,8 @@
module ActiveRecord #:nodoc:
class ActiveRecordError < StandardError #:nodoc:
end
+ class SubclassNotFound < ActiveRecordError #:nodoc:
+ end
class AssociationTypeMismatch < ActiveRecordError #:nodoc:
end
class SerializationTypeMismatch < ActiveRecordError #:nodoc:
@@ -535,7 +537,7 @@ def human_attribute_name(attribute_key_name)
end
def descends_from_active_record? # :nodoc:
- superclass == Base
+ superclass == Base || !columns_hash.has_key?(inheritance_column)
end
def quote(object)
@@ -568,7 +570,20 @@ def benchmark(title)
# Finder methods must instantiate through this method to work with the single-table inheritance model
# that makes it possible to create objects of different types from the same table.
def instantiate(record)
- object = record_with_type?(record) ? compute_type(record[inheritance_column]).allocate : allocate
+ require_association_class(record[inheritance_column])
+
+ begin
+ object = record_with_type?(record) ? compute_type(record[inheritance_column]).allocate : allocate
+ rescue NameError
+ raise(
+ SubclassNotFound,
+ "The single-table inheritance mechanism failed to locate the subclass: '#{record[inheritance_column]}'. " +
+ "This error is raised because the column '#{inheritance_column}' is reserved for storing the class in case of inheritance. " +
+ "Please rename this column if you didn't intend it to be used for storing the inheritance class " +
+ "or overwrite #{self.to_s}.inheritance_column to use another column for that information."
+ )
+ end
+
object.instance_variable_set("@attributes", record)
return object
end
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6 activerecord/test/fixtures/project.rb
@@ -1,4 +1,10 @@
class Project < ActiveRecord::Base
has_and_belongs_to_many :developers, :uniq => true
has_and_belongs_to_many :developers_named_david, :class_name => "Developer", :conditions => "name = 'David'", :uniq => true
+end
+
+class SpecialProject < Project
+ def hello_world
+ "hello there!"
+ end
end
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2 activerecord/test/fixtures/topic.rb
@@ -3,7 +3,7 @@ class Topic < ActiveRecord::Base
serialize :content
before_create :default_written_on
- before_destroy :destroy_children #'self.class.delete_all "parent_id = #{id}"'
+ before_destroy :destroy_children
def parent
self.class.find(parent_id)
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34 activerecord/test/inheritance_test.rb
@@ -1,20 +1,13 @@
require 'abstract_unit'
require 'fixtures/company'
-
+require 'fixtures/project'
class InheritanceTest < Test::Unit::TestCase
- def setup
- @company_fixtures = create_fixtures "companies"
- end
+ fixtures :companies, :projects
- def switch_to_alt_inheritance_column
- # we don't want misleading test results, so get rid of the values in the type column
- Company.find_all(nil, "id").each do |c|
- c['type'] = nil
- c.save
- end
-
- def Company.inheritance_column() "ruby_type" end
+ def test_a_bad_type_column
+ Company.connection.insert "INSERT INTO companies (id, type, name) VALUES(100, 'bad_class!', 'Not happening')"
+ assert_raises(ActiveRecord::SubclassNotFound) { Company.find(100) }
end
def test_inheritance_find
@@ -122,4 +115,21 @@ def test_alt_complex_inheritance
switch_to_alt_inheritance_column
test_complex_inheritance
end
+
+ def test_inheritance_without_mapping
+ assert_kind_of SpecialProject, SpecialProject.find(1)
+ assert_nothing_raised { SpecialProject.create("name" => "And breaaaaathe!") }
+
+ end
+
+ private
+ def switch_to_alt_inheritance_column
+ # we don't want misleading test results, so get rid of the values in the type column
+ Company.find_all(nil, "id").each do |c|
+ c['type'] = nil
+ c.save
+ end
+
+ def Company.inheritance_column() "ruby_type" end
+ end
end

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