Object
The Translator class encapsulates the logic and callbacks necessary for converting string data to a value of some specified type. Every Database instance may have a Translator instance, in order to assist in type translation (Database#type_translation).
Further, applications may define their own custom type translation logic by registering translator blocks with the corresponding database’s translator instance (Database#translator).
Create a new Translator instance. It will be preinitialized with default translators for most SQL data types.
# File lib/sqlite3/translator.rb, line 18 18: def initialize 19: @translators = Hash.new( proc { |type,value| value } ) 20: @type_name_cache = {} 21: register_default_translators 22: end
Add a new translator block, which will be invoked to process type translations to the given type. The type should be an SQL datatype, and may include parentheses (i.e., “VARCHAR(30)”). However, any parenthetical information is stripped off and discarded, so type translation decisions are made solely on the “base” type name.
The translator block itself should accept two parameters, “type” and “value”. In this case, the “type” is the full type name (including parentheses), so the block itself may include logic for changing how a type is translated based on the additional data. The “value” parameter is the (string) data to convert.
The block should return the translated value.
# File lib/sqlite3/translator.rb, line 37 37: def add_translator( type, &block ) # :yields: type, value 38: @translators[ type_name( type ) ] = block 39: end
Translate the given string value to a value of the given type. In the absense of an installed translator block for the given type, the value itself is always returned. Further, nil values are never translated, and are always passed straight through regardless of the type parameter.
# File lib/sqlite3/translator.rb, line 45 45: def translate( type, value ) 46: unless value.nil? 47: # FIXME: this is a hack to support Sequel 48: if type && %{ datetime timestamp }.include?(type.downcase) 49: @translators[ type_name( type ) ].call( type, value.to_s ) 50: else 51: @translators[ type_name( type ) ].call( type, value ) 52: end 53: end 54: end
Register the default translators for the current Translator instance. This includes translators for most major SQL data types.
# File lib/sqlite3/translator.rb, line 69 69: def register_default_translators 70: [ "time", 71: "timestamp" ].each { |type| add_translator( type ) { |t, v| Time.parse( v ) } } 72: 73: add_translator( "date" ) { |t,v| Date.parse(v) } 74: add_translator( "datetime" ) { |t,v| DateTime.parse(v) } 75: 76: [ "decimal", 77: "float", 78: "numeric", 79: "double", 80: "real", 81: "dec", 82: "fixed" ].each { |type| add_translator( type ) { |t,v| v.to_f } } 83: 84: [ "integer", 85: "smallint", 86: "mediumint", 87: "int", 88: "bigint" ].each { |type| add_translator( type ) { |t,v| v.to_i } } 89: 90: [ "bit", 91: "bool", 92: "boolean" ].each do |type| 93: add_translator( type ) do |t,v| 94: !( v.strip.gsub(/00+/,"0") == "0" || 95: v.downcase == "false" || 96: v.downcase == "f" || 97: v.downcase == "no" || 98: v.downcase == "n" ) 99: end 100: end 101: 102: add_translator( "tinyint" ) do |type, value| 103: if type =~ /\(\s*1\s*\)/ 104: value.to_i == 1 105: else 106: value.to_i 107: end 108: end 109: end
A convenience method for working with type names. This returns the “base” type name, without any parenthetical data.
# File lib/sqlite3/translator.rb, line 58 58: def type_name( type ) 59: @type_name_cache[type] ||= begin 60: type = "" if type.nil? 61: type = $1 if type =~ /^(.*?)\(/ 62: type.upcase 63: end 64: end
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