Add ActiveRecord::SchemaDumper for dumping a DB schema to a pure-ruby file, making it easier to consolidate large migration lists and port database schemas between databases.

git-svn-id: http://svn-commit.rubyonrails.org/rails/trunk@2312 5ecf4fe2-1ee6-0310-87b1-e25e094e27de

5 files changed, 197 insertions, 24 deletions

diff --git a/activerecord/lib/active_record/connection_adapters/abstract_adapter.rb b/activerecord/lib/active_record/connection_adapters/abstract_adapter.rb
index cbc8e7c273..1d09fa0f37 100755
--- a/activerecord/lib/active_record/connection_adapters/abstract_adapter.rb
+++ b/activerecord/lib/active_record/connection_adapters/abstract_adapter.rb
@@ -152,13 +152,13 @@ module ActiveRecord
 
   module ConnectionAdapters # :nodoc:
     class Column # :nodoc:
-      attr_reader :name, :default, :type, :limit
+      attr_reader :name, :default, :type, :limit, :null
       # The name should contain the name of the column, such as "name" in "name varchar(250)"
       # The default should contain the type-casted default of the column, such as 1 in "count int(11) DEFAULT 1"
       # The type parameter should either contain :integer, :float, :datetime, :date, :text, or :string
       # The sql_type is just used for extracting the limit, such as 10 in "varchar(10)"
-      def initialize(name, default, sql_type = nil)
-        @name, @default, @type = name, type_cast(default), simplified_type(sql_type)
+      def initialize(name, default, sql_type = nil, null = true)
+        @name, @default, @type, @null = name, type_cast(default), simplified_type(sql_type), null
         @limit = extract_limit(sql_type) unless sql_type.nil?
       end
 
@@ -275,6 +275,12 @@ module ActiveRecord
       # Returns a record hash with the column names as a keys and fields as values.
       def select_one(sql, name = nil) end
 
+      # Returns an array of table names for the current database.
+      def tables(name = nil) end
+
+      # Returns an array of indexes for the given table.
+      def indexes(table_name, name = nil) end
+
       # Returns an array of column objects for the table specified by +table_name+.
       def columns(table_name, name = nil) end
 
@@ -423,12 +429,46 @@ module ActiveRecord
         raise NotImplementedError, "rename_column is not implemented"
       end
 
-      def add_index(table_name, column_name, index_type = '')
-        execute "CREATE #{index_type} INDEX #{table_name}_#{column_name.to_a.first}_index ON #{table_name} (#{column_name.to_a.join(", ")})"
-      end
+      # Create a new index on the given table. By default, it will be named
+      # <code>"#{table_name}_#{column_name.to_a.first}_index"</code>, but you
+      # can explicitly name the index by passing <code>:name => "..."</code>
+      # as the last parameter. Unique indexes may be created by passing
+      # <code>:unique => true</code>.
+      def add_index(table_name, column_name, options = {})
+        index_name = "#{table_name}_#{column_name.to_a.first}_index"
 
-      def remove_index(table_name, column_name)
-        execute "DROP INDEX #{table_name}_#{column_name}_index ON #{table_name}"
+        if Hash === options # legacy support, since this param was a string
+          index_type = options[:unique] ? "UNIQUE" : ""
+          index_name = options[:name] || index_name
+        else
+          index_type = options
+        end
+
+        execute "CREATE #{index_type} INDEX #{index_name} ON #{table_name} (#{column_name.to_a.join(", ")})"
+      end
+
+      # Remove the given index from the table.
+      #
+      #   remove_index :my_table, :column => :foo
+      #   remove_index :my_table, :name => :my_index_on_foo
+      #
+      # The first version will remove the index named
+      # <code>"#{my_table}_#{column}_index"</code> from the table. The
+      # second removes the named column from the table.
+      def remove_index(table_name, options = {})
+        if Hash === options # legacy support
+          if options[:column]
+            index_name = "#{table_name}_#{options[:column]}_index"
+          elsif options[:name]
+            index_name = options[:name]
+          else
+            raise ArgumentError, "You must specify the index name"
+          end
+        else
+          index_name = "#{table_name}_#{options}_index"
+        end
+
+        execute "DROP INDEX #{index_name} ON #{table_name}"
       end
       
       def supports_migrations?
@@ -504,6 +544,9 @@ module ActiveRecord
         end
     end
 
+    class IndexDefinition < Struct.new(:table, :name, :unique, :columns)
+    end
+
     class ColumnDefinition < Struct.new(:base, :name, :type, :limit, :default, :null)
       def to_sql
         column_sql = "#{name} #{type_to_sql(type.to_sym, limit)}"
diff --git a/activerecord/lib/active_record/connection_adapters/mysql_adapter.rb b/activerecord/lib/active_record/connection_adapters/mysql_adapter.rb
index 6dbf315396..426d035bae 100755
--- a/activerecord/lib/active_record/connection_adapters/mysql_adapter.rb
+++ b/activerecord/lib/active_record/connection_adapters/mysql_adapter.rb
@@ -102,10 +102,31 @@ module ActiveRecord
         result.nil? ? nil : result.first
       end
 
+      def tables(name = nil)
+        tables = []
+        execute("SHOW TABLES", name).each { |field| tables << field[0] }
+        tables
+      end
+
+      def indexes(table_name, name = nil)
+        indexes = []
+        current_index = nil
+        execute("SHOW KEYS FROM #{table_name}", name).each do |row|
+          if current_index != row[2]
+            next if row[2] == "PRIMARY" # skip the primary key
+            current_index = row[2]
+            indexes << IndexDefinition.new(row[0], row[2], row[1] == "0", [])
+          end
+
+          indexes.last.columns << row[4]
+        end
+        indexes
+      end
+
       def columns(table_name, name = nil)
         sql = "SHOW FIELDS FROM #{table_name}"
         columns = []
-        execute(sql, name).each { |field| columns << Column.new(field[0], field[4], field[1]) }
+        execute(sql, name).each { |field| columns << Column.new(field[0], field[4], field[1], field[2] == "YES") }
         columns
       end
 
diff --git a/activerecord/lib/active_record/connection_adapters/sqlite_adapter.rb b/activerecord/lib/active_record/connection_adapters/sqlite_adapter.rb
index af2de4f706..116e20999a 100644
--- a/activerecord/lib/active_record/connection_adapters/sqlite_adapter.rb
+++ b/activerecord/lib/active_record/connection_adapters/sqlite_adapter.rb
@@ -150,17 +150,27 @@ module ActiveRecord
       def commit_db_transaction()   @connection.commit      end
       def rollback_db_transaction() @connection.rollback    end
 
-
-      def tables
-        execute('.table').map { |table| Table.new(table) }
+      def tables(name = nil)
+        execute("SELECT name FROM sqlite_master WHERE type = 'table'", name).map do |row|
+          row[0]
+        end
       end
 
       def columns(table_name, name = nil)
         table_structure(table_name).map { |field|
-          SQLiteColumn.new(field['name'], field['dflt_value'], field['type'])
+          SQLiteColumn.new(field['name'], field['dflt_value'], field['type'], field['notnull'] == "0")
         }
       end
 
+      def indexes(table_name, name = nil)
+        execute("PRAGMA index_list(#{table_name})", name).map do |row|
+          index = IndexDefinition.new(table_name, row['name'])
+          index.unique = row['unique'] != '0'
+          index.columns = execute("PRAGMA index_info(#{index.name})").map { |col| col['name'] }
+          index
+        end
+      end
+
       def primary_key(table_name)
         column = table_structure(table_name).find {|field| field['pk'].to_i == 1}
         column ? column['name'] : nil
@@ -222,17 +232,6 @@ module ActiveRecord
           end
         end
         
-        def indexes(table_name)
-          execute("PRAGMA index_list(#{table_name})").map do |index|
-            index_info = execute("PRAGMA index_info(#{index['name']})")
-            {
-              :name    => index['name'],
-              :unique  => index['unique'].to_i == 1,
-              :columns => index_info.map {|info| info['name']}
-            }
-          end
-        end
-        
         def alter_table(table_name, options = {}) #:nodoc:
           altered_table_name = "altered_#{table_name}"
           caller = lambda {|definition| yield definition if block_given?}
diff --git a/activerecord/lib/active_record/schema.rb b/activerecord/lib/active_record/schema.rb
new file mode 100644
index 0000000000..1cb4aec3c8
--- /dev/null
+++ b/activerecord/lib/active_record/schema.rb
@@ -0,0 +1,23 @@
+module ActiveRecord
+
+  class Schema < Migration #:nodoc:
+    private_class_method :new
+
+    def self.define(info={}, &block)
+      instance_eval(&block)
+
+      unless info.empty?
+        initialize_schema_information
+        cols = columns('schema_info')
+
+        info = info.map do |k,v|
+          v = quote(v, cols.detect { |c| c.name == k.to_s })
+          "#{k} = #{v}"
+        end
+
+        update "UPDATE schema_info SET #{info.join(", ")}"
+      end
+    end
+  end
+
+end
diff --git a/activerecord/lib/active_record/schema_dumper.rb b/activerecord/lib/active_record/schema_dumper.rb
new file mode 100644
index 0000000000..e086c17841
--- /dev/null
+++ b/activerecord/lib/active_record/schema_dumper.rb
@@ -0,0 +1,87 @@
+module ActiveRecord
+
+  # This class is used to dump the database schema for some connection to some
+  # output format (i.e., ActiveRecord::Schema).
+  class SchemaDumper
+    private_class_method :new
+
+    def self.dump(connection=ActiveRecord::Base.connection, stream=STDOUT)
+      new(connection).dump(stream)
+      stream
+    end
+
+    def dump(stream)
+      header(stream)
+      tables(stream)
+      trailer(stream)
+      stream
+    end
+
+    private
+
+      def initialize(connection)
+        @connection = connection
+        @types = @connection.native_database_types
+        @info = @connection.select_one("SELECT * FROM schema_info") rescue nil
+      end
+
+      def header(stream)
+        define_params = @info ? ":version => #{@info['version']}" : ""
+
+        stream.puts <<HEADER
+# This file is autogenerated. Instead of editing this file, please use the
+# migrations feature of ActiveRecord to incrementally modify your database, and
+# then regenerate this schema definition.
+
+require 'active_record/schema'
+
+ActiveRecord::Schema.define(#{define_params}) do
+
+HEADER
+      end
+
+      def trailer(stream)
+        stream.puts "end"
+      end
+
+      def tables(stream)
+        @connection.tables.sort.each do |tbl|
+          next if tbl == "schema_info"
+          table(tbl, stream)
+        end
+      end
+
+      def table(table, stream)
+        columns = @connection.columns(table)
+
+        stream.print "  create_table #{table.inspect}"
+        stream.print ", :id => false" if !columns.detect { |c| c.name == "id" }
+        stream.puts " do |t|"
+
+        columns.each do |column|
+          next if column.name == "id"
+          stream.print "    t.column #{column.name.inspect}, #{column.type.inspect}"
+          stream.print ", :limit => #{column.limit.inspect}" if column.limit != @types[column.type][:limit]
+          stream.print ", :default => #{column.default.inspect}" if column.default
+          stream.print ", :null => false" if !column.null
+          stream.puts
+        end
+
+        stream.puts "  end"
+        stream.puts
+
+        indexes(table, stream)
+      end
+
+      def indexes(table, stream)
+        indexes = @connection.indexes(table)
+        indexes.each do |index|
+          stream.print "  add_index #{index.table.inspect}, #{index.columns.inspect}, :name => #{index.name.inspect}"
+          stream.print ", :unique => true" if index.unique
+          stream.puts
+        end
+        stream.puts unless indexes.empty?
+      end
+  end
+
+end