Class: ActiveRecord::ConnectionAdapters::JdbcTypeConverter
- Inherits:
-
Object
- Object
- ActiveRecord::ConnectionAdapters::JdbcTypeConverter
- Defined in:
- lib/arjdbc/jdbc/type_converter.rb
Overview
I want to use JDBC's DatabaseMetaData#getTypeInfo to choose the best native types to use for ActiveRecord's Adapter#native_database_types in a database-independent way, but apparently a database driver can return multiple types for a given java.sql.Types constant. So this type converter uses some heuristics to try to pick the best (most common) type to use. It's not great, it would be better to just delegate to each database's existing AR adapter's native_database_types method, but I wanted to try to do this in a way that didn't pull in all the other adapters as dependencies. Improvements appreciated.
Constant Summary collapse
- AR_TO_JDBC_TYPES =
The basic ActiveRecord types, mapped to an array of procs that are used to #select the best type. The procs are used as selectors in order until there is only one type left. If all the selectors are applied and there is still more than one type, an exception will be raised.
{ :string => [ lambda {|r| Jdbc::Types::VARCHAR == r['data_type'].to_i}, lambda {|r| r['type_name'] =~ /^varchar/i}, lambda {|r| r['type_name'] =~ /^varchar$/i}, lambda {|r| r['type_name'] =~ /varying/i}], :text => [ lambda {|r| TEXT_TYPES.include?(r['data_type'].to_i)}, lambda {|r| r['type_name'] =~ /^text$/i}, # For Informix lambda {|r| r['type_name'] =~ /sub_type 1$/i}, # For FireBird lambda {|r| r['type_name'] =~ /^(text|clob)$/i}, lambda {|r| r['type_name'] =~ /^character large object$/i}, lambda {|r| r['sql_data_type'] == 2005}], :integer => [ lambda {|r| Jdbc::Types::INTEGER == r['data_type'].to_i}, lambda {|r| r['type_name'] =~ /^integer$/i}, lambda {|r| r['type_name'] =~ /^int4$/i}, lambda {|r| r['type_name'] =~ /^int$/i}], :decimal => [ lambda {|r| Jdbc::Types::DECIMAL == r['data_type'].to_i}, lambda {|r| r['type_name'] =~ /^decimal$/i}, lambda {|r| r['type_name'] =~ /^numeric$/i}, lambda {|r| r['type_name'] =~ /^number$/i}, lambda {|r| r['type_name'] =~ /^real$/i}, lambda {|r| r['precision'] == '38'}, lambda {|r| r['data_type'].to_i == Jdbc::Types::DECIMAL}], :float => [ lambda {|r| FLOAT_TYPES.include?(r['data_type'].to_i)}, lambda {|r| r['data_type'].to_i == Jdbc::Types::REAL}, #Prefer REAL to DOUBLE for Postgresql lambda {|r| r['type_name'] =~ /^float/i}, lambda {|r| r['type_name'] =~ /^double$/i}, lambda {|r| r['type_name'] =~ /^real$/i}, lambda {|r| r['precision'] == '15'}], :datetime => [ lambda {|r| Jdbc::Types::TIMESTAMP == r['data_type'].to_i}, lambda {|r| r['type_name'] =~ /^datetime$/i}, lambda {|r| r['type_name'] =~ /^timestamp$/i}, lambda {|r| r['type_name'] =~ /^datetime.+/i}, lambda {|r| r['type_name'] =~ /^date/i}, lambda {|r| r['type_name'] =~ /^integer/i}], #Num of milliseconds for SQLite3 JDBC Driver :timestamp => [ lambda {|r| Jdbc::Types::TIMESTAMP == r['data_type'].to_i}, lambda {|r| r['type_name'] =~ /^timestamp$/i}, lambda {|r| r['type_name'] =~ /^datetime$/i}, lambda {|r| r['type_name'] =~ /^datetime.+/i}, lambda {|r| r['type_name'] =~ /^date/i}, lambda {|r| r['type_name'] =~ /^integer/i}], #Num of milliseconds for SQLite3 JDBC Driver :time => [ lambda {|r| Jdbc::Types::TIME == r['data_type'].to_i}, lambda {|r| r['type_name'] =~ /^time$/i}, lambda {|r| r['type_name'] =~ /^datetime$/i}, lambda {|r| r['type_name'] =~ /^datetime.+/i}, # For Informix lambda {|r| r['type_name'] =~ /^date/i}, lambda {|r| r['type_name'] =~ /^integer/i}], #Num of milliseconds for SQLite3 JDBC Driver :date => [ lambda {|r| Jdbc::Types::DATE == r['data_type'].to_i}, lambda {|r| r['type_name'] =~ /^date$/i}, lambda {|r| r['type_name'] =~ /^date/i}, lambda {|r| r['type_name'] =~ /^integer/i}], #Num of milliseconds for SQLite3 JDBC Driver3 :binary => [ lambda {|r| BINARY_TYPES.include?(r['data_type'].to_i)}, lambda {|r| r['type_name'] =~ /^blob/i}, lambda {|r| r['type_name'] =~ /sub_type 0$/i}, # For FireBird lambda {|r| r['type_name'] =~ /^varbinary$/i}, # We want this sucker for Mimer lambda {|r| r['type_name'] =~ /^binary$/i}, ], :boolean => [ lambda {|r| Jdbc::Types::BIT == r['data_type'].to_i && r['precision'].to_i == 1}, lambda {|r| Jdbc::Types::TINYINT == r['data_type'].to_i}, lambda {|r| r['type_name'] =~ /^bool/i}, lambda {|r| r['data_type'].to_i == Jdbc::Types::BIT}, lambda {|r| r['type_name'] =~ /^tinyint$/i}, lambda {|r| r['type_name'] =~ /^decimal$/i}, lambda {|r| r['type_name'] =~ /^integer$/i}] }
Instance Method Summary collapse
- #choose_best_types ⇒ Object
- #choose_type(ar_type) ⇒ Object
-
#initialize(types) ⇒ JdbcTypeConverter
constructor
A new instance of JdbcTypeConverter.
- #set_limit_to_nonzero_precision(map, row) ⇒ Object
Constructor Details
#initialize(types) ⇒ JdbcTypeConverter
Returns a new instance of JdbcTypeConverter.
95 96 97 98 |
# File 'lib/arjdbc/jdbc/type_converter.rb', line 95 def initialize(types) @types = types @types.each {|t| t['type_name'] ||= t['local_type_name']} # Sybase driver seems to want 'local_type_name' end |
Instance Method Details
#choose_best_types ⇒ Object
100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 |
# File 'lib/arjdbc/jdbc/type_converter.rb', line 100 def choose_best_types type_map = {} @types.each do |row| name = row['type_name'].downcase k = name.to_sym type_map[k] = { :name => name } set_limit_to_nonzero_precision(type_map[k], row) end AR_TO_JDBC_TYPES.keys.each do |ar_type| typerow = choose_type(ar_type) type_map[ar_type] = { :name => typerow['type_name'].downcase } case ar_type when :integer, :string, :decimal set_limit_to_nonzero_precision(type_map[ar_type], typerow) when :boolean type_map[ar_type][:limit] = 1 end end type_map end |
#choose_type(ar_type) ⇒ Object
122 123 124 125 126 127 128 129 130 131 132 133 134 135 |
# File 'lib/arjdbc/jdbc/type_converter.rb', line 122 def choose_type(ar_type) types = @types AR_TO_JDBC_TYPES[ar_type].each do |proc| new_types = types.reject {|r| r["data_type"].to_i == Jdbc::Types::OTHER} new_types = new_types.select(&proc) new_types = new_types.inject([]) do |typs,t| typs << t unless typs.detect {|el| el['type_name'] == t['type_name']} typs end return new_types.first if new_types.length == 1 types = new_types if new_types.length > 0 end raise "unable to choose type for #{ar_type} from:\n#{types.collect{|t| t['type_name']}.inspect}" end |
#set_limit_to_nonzero_precision(map, row) ⇒ Object
137 138 139 140 141 |
# File 'lib/arjdbc/jdbc/type_converter.rb', line 137 def set_limit_to_nonzero_precision(map, row) if row['precision'] && row['precision'].to_i > 0 map[:limit] = row['precision'].to_i end end |