Class: TaliaCore::DataTypes::MimeMapping

Inherits:
Object
  • Object
show all
Defined in:
lib/talia_core/data_types/mime_mapping.rb

Overview

Mapping from Mime types to data classes and importing methods for DataRecord.

See the DataTypes::DataLoader module to see how the import works. In a nutshell, each MIME type can be connected either to a DataTypes::FileRecord type that will be used for new data records, or the MIME type can be connected to a handler method that will do the creation.

Default Mappings

See the source code of the mapping_hash method for the detailed default mapping. It goes something like this:

  • All image types (:jpeg, :tiff, :png, :gif, …) use DataTypes::ImageData

  • HTML, XML and all “transcription” types (:html, :xml, :tei, …) use DataTypes::XmlData

  • :text uses DataTypes::SimpleText

  • :pdf uses DataTypes::PdfData

  • The default (for unknow types) is to use DataTypes::FileRecord

Configure the MIME mappings for Talia

The mapping can be configured in Rails’ initializer files (e.g. config/initializers/talia.rb):

TaliaCore::DataTypes::MimeMapping.add_mapping(:tiff, :image_data, :create_iip)

Add a mapping for each MIME type that you need, or where you want to change the default mapping

Class Method Summary collapse

Class Method Details

.add_mapping(mime_type, data_class, handler = nil) ⇒ Object

Set a new mapping for the given MIME type. If only a class is given, this will use the class to create new data records from. If a symbol is given for data_class, this will take the corresponding class from TaliaCore::DataTypes.

Examples

# Uses DataTypes::ImageData#create_iip to create new records
TaliaCore::DataTypes::MimeMapping.add_mapping(:tiff, :image_data, :create_iip)

# Use the DataTypes::ImageData class for new data records, and create records
# in the default way (using create_with_file or similar)
TaliaCore::DataTypes::MimeMapping.add_mapping(:png, DataTypes::ImageData)



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# File 'lib/talia_core/data_types/mime_mapping.rb', line 64

def add_mapping(mime_type, data_class, handler = nil)
  mapping = {}
  if(!data_class.is_a?(Class))
    data_class = TaliaCore::DataTypes.const_get(data_class.to_s.camelize)
  end
  
  raise("Error: #{data_class} is not a valid data class.") unless(data_class.is_a?(Class) && (data_class <= DataRecord))
  
  mapping[:type] = data_class
  mapping[:loader] = handler.to_sym if(handler)
  mapping_hash[symbol_for(mime_type)] = mapping
  true
end

.class_type_from(mime_type) ⇒ Object

Gets the data class for the given mime type. For loaders configured through add_mapping, this will always return the class corresponding to data_class. (Otherwise it will return the data_class configured in the default mapping)



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# File 'lib/talia_core/data_types/mime_mapping.rb', line 39

def class_type_from(mime_type)
  mapping_for(mime_type)[:type]
end

.loader_type_from(mime_type) ⇒ Object

Return the “loader type” for the given MIME type. This will return the handler (as a symbol, see add_mapping) if set. If no handler is set, it will return the data_class (as class_type_from).



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# File 'lib/talia_core/data_types/mime_mapping.rb', line 46

def loader_type_from(mime_type)
  map = mapping_for(mime_type)
  map[:loader] || map[:type]
end

.mapping_hash ⇒ Object

Returns the current mapping. This will be automatically initialized with the default mappings.



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# File 'lib/talia_core/data_types/mime_mapping.rb', line 80

def mapping_hash
  @mapping ||= {
    :xml => { :type => DataTypes::XmlData },
    :html =>{ :type => DataTypes::XmlData },
    :tei => { :type => DataTypes::XmlData },
    :tei_p5 => { :type => DataTypes::XmlData },
    :tei_p4 => { :type => DataTypes::XmlData }, 
    :gml => { :type => DataTypes::XmlData },
    :wittei => { :type => DataTypes::XmlData },
    :hnml => { :type => DataTypes::XmlData },
    :jpeg => { :type => DataTypes::ImageData },
    :tiff => { :type => DataTypes::ImageData },
    :png => { :type => DataTypes::ImageData },
    :gif => { :type => DataTypes::ImageData },
    :bmp => { :type => DataTypes::ImageData },
    :pdf => { :type => DataTypes::PdfData },
    :text => { :type => DataTypes::SimpleText },            
    # Default fallback handler
    :default => { :type => FileRecord }
  }
end