Merge branch 'iamadalek-support-for-generated-columns'

# Conflicts:
#	Gemfile.lock

lib/lhm/intersection.rb

@@ -4,10 +4,11 @@
 module Lhm
   #  Determine and format columns common to origin and destination.
   class Intersection
-    def initialize(origin, destination, renames = {})
+    def initialize(origin, destination, renames = {}, generated_column_names = [])
       @origin = origin
       @destination = destination
       @renames = renames
+      @generated_column_names = generated_column_names
     end
 
     def origin
@@ -21,7 +22,7 @@ def destination
     private
 
     def common
-      (@origin.columns.keys & @destination.columns.keys).sort
+      ((@origin.columns.keys & @destination.columns.keys) - @generated_column_names).sort
     end
 
     module Joiners

lib/lhm/migration.rb

@@ -8,20 +8,21 @@ module Lhm
   class Migration
     attr_reader :origin, :destination, :conditions, :renames
 
-    def initialize(origin, destination, conditions = nil, renames = {}, time = Time.now)
+    def initialize(origin, destination, conditions = nil, renames = {}, time = Time.now, generated_column_names = [])
       @origin = origin
       @destination = destination
       @conditions = conditions
       @renames = renames
       @table_name = TableName.new(@origin.name, time)
+      @generated_column_names = generated_column_names
     end
 
     def archive_name
       @archive_name ||= @table_name.archived
     end
 
     def intersection
-      Intersection.new(@origin, @destination, @renames)
+      Intersection.new(@origin, @destination, @renames, @generated_column_names)
     end
 
     def origin_name

lib/lhm/migrator.rb

@@ -216,7 +216,11 @@ def execute
       @statements.each do |stmt|
         @connection.execute(tagged(stmt))
       end
-      Migration.new(@origin, destination_read, conditions, renames)
+      Migration.new(@origin, destination_read, conditions, renames, Time.now, generated_column_names)
+    end
+
+    def generated_column_names
+      @connection.columns(@origin.name).select(&:virtual?).map(&:name)
     end
 
     def destination_create

spec/integration/lhm_spec.rb

@@ -531,6 +531,61 @@
       end
     end
 
+    it 'works when table has generated columns' do
+      table_create(:users)
+      execute("insert into `users` set id = 1, `username` = 'memyself'")
+      execute("insert into `users` set id = 2, `username` = 'youyourself'")
+
+      # Add a generated column
+      Lhm.change_table(:users) do |t|
+        t.add_column(:sample_generated_column, 'VARCHAR(255) GENERATED ALWAYS AS (SUBSTRING(`username`, -2))')
+      end
+
+      # Without the handling of generated columns
+      Lhm::Migrator.any_instance.stubs(:generated_column_names).returns([])
+      # without the Migration passing in generated columns to Intersection, we observe an error as an attempt to write
+      # directly into generated columns will fail.
+      exception = assert_raises ActiveRecord::StatementInvalid do
+        Lhm.change_table(:users) do |t|
+          t.add_column(:sample_additional_column, "VARCHAR(255)")
+        end
+      end
+      assert_match "The value specified for generated column 'sample_generated_column' in table 'lhmn_users' is not allowed.", exception.message
+
+      Lhm.cleanup(true)
+
+      # With the handling of generated columns
+      Lhm::Migrator.any_instance.unstub(:generated_column_names)
+      # As we are now skipping the writing to generated columns, this migration should succeed
+      Lhm.change_table(:users) do |t|
+        t.add_column(:sample_additional_column, "VARCHAR(255)")
+      end
+
+      slave do
+        # new column is added
+        value(table_read(:users).columns['sample_additional_column']).must_equal({
+          :type => 'varchar(255)',
+          :is_nullable => 'YES',
+          :column_default => nil,
+          :comment => '',
+          :collate => 'utf8_general_ci',
+        })
+
+        # generated column remains intact
+        value(table_read(:users).columns['sample_generated_column']).must_equal({
+          :type => 'varchar(255)',
+          :is_nullable => 'YES',
+          :column_default => nil,
+          :comment => '',
+          :collate => 'utf8_general_ci',
+        })
+      end
+
+      result = select_one('SELECT sample_generated_column FROM users')
+      # generated column populated appropriately
+      assert_match "lf", result["sample_generated_column"]
+    end
+
     it 'works when mysql reserved words are used' do
       table_create(:lines)
       execute("insert into `lines` set id = 1, `between` = 'foo'")