Issue #18: belongs_to should not cause an assumption that Migrant is …

…being used on a model

lib/migrant/migration_generator.rb

@@ -29,7 +29,7 @@ def run
       # Rails 3.2+ caches table (non) existence so this needs to be cleared before we start
       ActiveRecord::Base.connection.schema_cache.clear! if ActiveRecord::Base.connection.respond_to?(:schema_cache)
 
-      ActiveRecord::Base.descendants.select { |model| model.schema && model.schema.requires_migration? }.each do |model|
+      ActiveRecord::Base.descendants.select { |model| model.structure_defined? && model.schema.requires_migration? }.each do |model|
         model.reset_column_information # db:migrate doesn't do this
         @table_name = model.table_name
         @columns = Hash[[:changed, :added, :deleted, :renamed, :transferred].collect { |a| [a,[]] }]  

lib/migrant/model_extensions.rb

@@ -21,6 +21,8 @@ def structure(type=nil, &block)
       # So, my_field in the structure block actually calls Migrant::Schema.my_field
 
       create_migrant_schema
+      @structure_defined = true
+
       if self.superclass == ActiveRecord::Base
         @schema.define_structure(type, &block)
         @schema.validations.each do |field, validation_options|
@@ -41,6 +43,10 @@ def structure(type=nil, &block)
       end
     end
 
+    def structure_defined?
+      @schema && @structure_defined || false
+    end
+
     # Same as defining a structure block, but with no attributes besides
     # relationships (such as in a many-to-many)
     def no_structure

test/rails_app/app/models/non_migrant_model.rb

@@ -0,0 +1,3 @@
+class NonMigrantModel < ActiveRecord::Base
+  belongs_to :business
+end

test/test_data_schema.rb

@@ -99,4 +99,8 @@ class TestDataSchema < Test::Unit::TestCase
     end
   end
 
+  should "still indicate a structure is not defined if a belongs_to association is added" do
+    assert_equal(false, NonMigrantModel.structure_defined?)
+    assert_equal(true, Business.structure_defined?)
+  end
 end