Fixes bug when blowing away migrations into one file.

.gitignore

@@ -1 +1,3 @@
 pkg/*
+.swp
+*.swp

lib/db_migrate_merge.rb

@@ -0,0 +1,32 @@
+class DbMigrateMerge
+  def self.generate_down_indexes lines
+    indexes = lines.collect do |line|
+      columns_regex = /add_index "[^"]+", ?(?::column ?=> ?)?(\[[^\]]+\]|"[^"]+")/
+
+      index_regex = /add_index "[^"]+", ?(?::name ?=> ?)?"([^"]+)"/
+      table_regex = /add_index "([^"]+)"/
+
+      if line =~ table_regex
+        table_name = $1
+        remove = "remove_index :#{table_name},"
+
+        columns = line =~ columns_regex
+        if columns
+          if $1.index "["
+            "#{remove} :column => #{$1}"
+          else
+            "#{remove} :column => [#{$1}]"
+          end
+        elsif line =~ index_regex
+          "#{remove} :name => \"#{$1}\""
+        else
+          raise Exception.new "Expected to find an index name or column names in the db/schema.rb file but none were found:\n #{line}"
+        end
+      end
+
+    end
+
+    indexes.compact.reverse
+  end
+
+end

lib/tasks/db_migrate_merge.rake

@@ -1,49 +1,50 @@
 require 'fileutils'
 namespace :db do
-  
+
   namespace :migrate do
-    
+
     desc "Uses schema.rb to build a new base migration with the timestamp of the current migration. Other migrations are   moved to a backup folder."
-    task :compact => [:abort_if_pending_migrations, :environment] do 
-      
+    task :compact => [:abort_if_pending_migrations, :environment] do
+
       file = File.read("#{RAILS_ROOT}/db/schema.rb")
-      
+
       main_content_regex = /ActiveRecord::Schema.define\(:version => (.*)\) do(.*)^end/m
       main_content_regex.match file
       create_part = $2 # the second group holds what I want.
-
-      lines = file.split("\n")     
-
-      index_regex = /add_index "(.*)", (.*):name => "(.*)"/
+
+      lines = file.split("\n")
+
       table_regex = /create_table (.*),(.*)/
-
+
+      index_regex = /add_index "(.*)", \[(.*)\], :name => "(.*)"/
+
       tables = lines.collect{|line| "  drop_table #{$1}" if line =~ table_regex }
-      indexes = lines.collect{|line| "  remove_index :#{$1}, :name => :#{$3}" if line =~ index_regex}
-
+
       # hack to correct spacing so it "looks pretty"
       create_part.gsub!("\n", "\n  ")
-      
+
       # reverse the order so the indexes get taken out in the opposite order
       # they were added. Also add two spaces to the start of each line
       drop_tables =  tables.compact.reverse.join("\n  ")
-      drop_indexes = indexes.compact.reverse.join("\n  ")
-
+      drop_indexes = DbMigrateMerge.generate_down_indexes lines
+      drop_indexes = drop_indexes.join("\n    ")
+
       new_migration = %Q{# Migration created #{Time.now.to_s} by lazy_developer
 class InitialMigration < ActiveRecord::Migration
   def self.up
     #{create_part}
   end
-  
+
   def self.down
-  #{drop_indexes}
-  
+    #{drop_indexes}
+
   #{drop_tables}
   end
 end
 }
     version =  ActiveRecord::Migrator.current_version
     backups = RAILS_ROOT+"/db/migrate_#{version}"
-    
+
     svn=File.exist?(RAILS_ROOT+"/db/migrate/.svn")
     if svn
       `svn mkdir #{backups}`
@@ -55,19 +56,19 @@ end
       FileUtils.mv(RAILS_ROOT+"/db/migrate", backups)
       FileUtils.mkdir(RAILS_ROOT+"/db/migrate")
     end
-    
+
     new_file = RAILS_ROOT+"/db/migrate/#{version}_initial_migration.rb"
 
     File.open(new_file, "w") do |f|
       f << new_migration
     end
 
     `svn add #{new_file}` if svn
-    
+
     puts "Created #{new_file}."
     puts "Previous migrations are in #{backups}"
     end
-  
+
   end
-  
+
 end

spec/db_migrate_merge_spec.rb

@@ -0,0 +1,92 @@
+current_directory = File.join File.dirname(__FILE__)
+require File.join(current_directory, '../lib/db_migrate_merge')
+
+describe DbMigrateMerge do
+  describe "#remove_index" do
+    #___________________
+   it "handles indexes with just a column name" do
+      line = <<-eof
+add_index "versions", "versioned_type"
+eof
+
+      expected = <<-ex
+remove_index :versions, :column => ["versioned_type"]
+ex
+
+      DbMigrateMerge.generate_down_indexes([line]).should == expected[0..-2]
+    end
+
+
+
+
+
+    #___________________
+    it "handles indexes with only one column name and an index name" do
+
+      line = <<-eof
+add_index "audited", "transaction", :name => "index_audited_on_transaction"
+eof
+
+      expected_line = <<-eof
+remove_index :audited, :column => ["transaction"]
+eof
+
+      expected = [expected_line].join()[0..-2]
+      DbMigrateMerge.generate_down_indexes([line]).should == expected
+
+    end
+
+
+    #___________________
+    it "works with an array of column names and an index name" do
+      line = <<-eof
+add_index "versions", ["versioned_type", "versioned_id"], :name => "index_versions_on_versioned_type_and_versioned_id"
+eof
+
+      expected = <<-ex
+remove_index :versions, :column => ["versioned_type", "versioned_id"]
+ex
+      DbMigrateMerge.generate_down_indexes([line]).should == expected[0..-2]
+    end
+
+     it "handles indexes with a column name with the :column => hash rocket syntax" do
+      line = <<-eof
+add_index "versions", :column => ["versioned_type", "versioned_id"], :name => "index_versions_on_versioned_type_and_versioned_id"
+eof
+
+      expected = <<-ex
+remove_index :versions, :column => ["versioned_type", "versioned_id"]
+ex
+
+      DbMigrateMerge.generate_down_indexes([line]).should == expected[0..-2]
+
+      line = <<-eof
+add_index "versions", :column => ["versioned_type"], :name => "index_versions_on_versioned_type"
+eof
+
+      expected = <<-ex
+remove_index :versions, :column => ["versioned_type"]
+ex
+
+      DbMigrateMerge.generate_down_indexes([line]).should == expected[0..-2]
+
+
+    end
+
+
+
+     it "handles indexes with a column name with the :column => hash rocket syntax" do
+      line = <<-eof
+add_index "versions", :name => "index_versions_on_versioned_type_and_versioned_id"
+eof
+
+      expected = <<-ex
+remove_index :versions, :name => "index_versions_on_versioned_type_and_versioned_id"
+ex
+
+      DbMigrateMerge.generate_down_indexes([line]).should == expected[0..-2]
+
+    end
+  end
+
+end