Class: SQLite3::Translator

### Home Classes Methods

### In Files

- lib/sqlite3/translator.rb

### Parent

Object

### Methods

- ::new
- #add_translator
- #translate

### Files

- API_CHANGES.rdoc
- Manifest.txt
- README.rdoc

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# SQLite3::Translator

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).

### Public Class Methods

new() click to toggle source

Create a new Translator instance. It will be preinitialized with default translators for most SQL data types.

    # File lib/sqlite3/translator.rb, line 18
    def initialize
      @translators = Hash.new( proc { |type,value| value } )
      @type_name_cache = {}
      register_default_translators
    end

### Public Instance Methods

add_translator( type ) click to toggle source

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
    def add_translator( type, &block ) # :yields: type, value
      warn(#{caller[0]} is calling `add_translator`.Built in translators are deprecated and will be removed in version 2.0.0) if $VERBOSE
      @translators[ type_name( type ) ] = block
    end

translate( type, value ) click to toggle source

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 49
    def translate( type, value )
      unless value.nil?
        # FIXME: this is a hack to support Sequel
        if type && %{ datetime timestamp }.include?(type.downcase)
          @translators[ type_name( type ) ].call( type, value.to_s )
        else
          @translators[ type_name( type ) ].call( type, value )
        end
      end
    end

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