Merge pull request #7 from localytics/dbms-consolidation

Consolidate logic onto DatabaseMetadata

lib/active_record/connection_adapters/odbc_adapter.rb

@@ -10,7 +10,7 @@
 
 require 'odbc_adapter/column'
 require 'odbc_adapter/column_metadata'
-require 'odbc_adapter/dbms'
+require 'odbc_adapter/database_metadata'
 require 'odbc_adapter/registry'
 require 'odbc_adapter/type_caster'
 require 'odbc_adapter/version'
@@ -30,8 +30,8 @@ def odbc_connection(config) # :nodoc:
             raise ArgumentError, "No data source name (:dsn) or connection string (:conn_str) specified."
           end
 
-        dbms = ::ODBCAdapter::DBMS.new(connection)
-        dbms.adapter_class.new(connection, logger, dbms)
+        database_metadata = ::ODBCAdapter::DatabaseMetadata.new(connection)
+        database_metadata.adapter_class.new(connection, logger, database_metadata)
       end
 
       private
@@ -78,12 +78,12 @@ class ODBCAdapter < AbstractAdapter
       BOOLEAN_TYPE = 'BOOLEAN'.freeze
       ERR_DUPLICATE_KEY_VALUE = 23505
 
-      attr_reader :dbms
+      attr_reader :database_metadata
 
-      def initialize(connection, logger, dbms)
+      def initialize(connection, logger, database_metadata)
         super(connection, logger)
-        @connection = connection
-        @dbms       = dbms
+        @connection        = connection
+        @database_metadata = database_metadata
       end
 
       # Returns the human-readable name of the adapter. Use mixed case - one

lib/odbc_adapter/database_limits.rb

@@ -2,8 +2,8 @@ module ODBCAdapter
   module DatabaseLimits
     # Returns the maximum length of a table name.
     def table_alias_length
-      max_identifier_length = dbms.field_for(ODBC::SQL_MAX_IDENTIFIER_LEN)
-      max_table_name_length = dbms.field_for(ODBC::SQL_MAX_TABLE_NAME_LEN)
+      max_identifier_length = database_metadata.max_identifier_len
+      max_table_name_length = database_metadata.max_table_name_len
       [max_identifier_length, max_table_name_length].max
     end
   end

lib/odbc_adapter/database_metadata.rb

@@ -0,0 +1,44 @@
+module ODBCAdapter
+  # Caches SQLGetInfo output
+  class DatabaseMetadata
+    FIELDS = %i[
+      SQL_DBMS_NAME
+      SQL_DBMS_VER
+      SQL_IDENTIFIER_CASE
+      SQL_QUOTED_IDENTIFIER_CASE
+      SQL_IDENTIFIER_QUOTE_CHAR
+      SQL_MAX_IDENTIFIER_LEN
+      SQL_MAX_TABLE_NAME_LEN
+      SQL_USER_NAME
+      SQL_DATABASE_NAME
+    ]
+
+    attr_reader :values
+
+    def initialize(connection)
+      @values = Hash[FIELDS.map { |field| [field, connection.get_info(ODBC.const_get(field))] }]
+    end
+
+    def adapter_class
+      ODBCAdapter.adapter_for(dbms_name)
+    end
+
+    def upcase_identifiers?
+      @upcase_identifiers ||= (identifier_case == ODBC::SQL_IC_UPPER)
+    end
+
+    # A little bit of metaprogramming magic here to create accessors for each of
+    # the fields reported on by the DBMS.
+    FIELDS.each do |field|
+      define_method(field.to_s.downcase.gsub('sql_', '')) do
+        value_for(field)
+      end
+    end
+
+    private
+
+    def value_for(field)
+      values[field]
+    end
+  end
+end

lib/odbc_adapter/database_statements.rb

@@ -87,8 +87,7 @@ def dbms_type_cast(columns, values)
 
     # Assume received identifier is in DBMS's data dictionary case.
     def format_case(identifier)
-      case dbms.field_for(ODBC::SQL_IDENTIFIER_CASE)
-      when ODBC::SQL_IC_UPPER
+      if database_metadata.upcase_identifiers?
         identifier =~ /[a-z]/ ? identifier : identifier.downcase
       else
         identifier
@@ -114,8 +113,7 @@ def format_case(identifier)
     # Converts an identifier to the case conventions used by the DBMS.
     # Assume received identifier is in ActiveRecord case.
     def native_case(identifier)
-      case dbms.field_for(ODBC::SQL_IDENTIFIER_CASE)
-      when ODBC::SQL_IC_UPPER
+      if database_metadata.upcase_identifiers?
         identifier =~ /[A-Z]/ ? identifier : identifier.upcase
       else
         identifier

lib/odbc_adapter/quoting.rb

@@ -8,17 +8,16 @@ def quote_string(string)
     # Returns a quoted form of the column name.
     def quote_column_name(name)
       name = name.to_s
-      quote_char = dbms.field_for(ODBC::SQL_IDENTIFIER_QUOTE_CHAR).to_s.strip
+      quote_char = database_metadata.identifier_quote_char.to_s.strip
 
       return name if quote_char.length.zero?
       quote_char = quote_char[0]
 
       # Avoid quoting any already quoted name
       return name if name[0] == quote_char && name[-1] == quote_char
 
-      # If DBMS's SQL_IDENTIFIER_CASE = SQL_IC_UPPER, only quote mixed
-      # case names.
-      if dbms.field_for(ODBC::SQL_IDENTIFIER_CASE) == ODBC::SQL_IC_UPPER
+      # If upcase identifiers, only quote mixed case names.
+      if database_metadata.upcase_identifiers?
         return name unless (name =~ /([A-Z]+[a-z])|([a-z]+[A-Z])/)
       end
 

lib/odbc_adapter/schema_statements.rb

@@ -98,12 +98,12 @@ def primary_key(table_name)
     # Ensure it's shorter than the maximum identifier length for the current
     # dbms
     def index_name(table_name, options)
-      maximum = dbms.field_for(ODBC::SQL_MAX_IDENTIFIER_LEN) || 255
+      maximum = database_metadata.max_identifier_len || 255
       super(table_name, options)[0...maximum]
     end
 
     def current_database
-      dbms.field_for(ODBC::SQL_DATABASE_NAME).strip
+      database_metadata.database_name.strip
     end
   end
 end