Class: ROM::Mapper

Inherits:
Object
  • Object
show all
Includes:
DSL
Defined in:
lib/rom/mapper.rb,
lib/rom/mapper/dsl.rb,
lib/rom/mapper/version.rb,
lib/rom/mapper/model_dsl.rb,
lib/rom/mapper/attribute_dsl.rb

Overview

Mapper is a simple object that uses transformers to load relations

Defined Under Namespace

Modules: DSL, ModelDSL Classes: AttributeDSL

Constant Summary collapse

VERSION = 
'0.3.0'.freeze

Instance Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Methods included from DSL

included

Constructor Details

#initialize(header, processor = :transproc) ⇒ Mapper

This method is part of a private API. You should avoid using this method if possible, as it may be removed or be changed in the future.

Returns a new instance of Mapper.



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# File 'lib/rom/mapper.rb', line 74

def initialize(header, processor = :transproc)
  processor = Mapper.processors.fetch(processor)
  @transformers = self.class.headers(header).map do |header|
    processor.build(self, header)
  end
  @header = header
end

Instance Attribute Details

#header ⇒ Header (readonly)

This method is part of a private API. You should avoid using this method if possible, as it may be removed or be changed in the future.

Returns header that was used to build the transformers.

Returns:

  • (Header) —

    header that was used to build the transformers



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# File 'lib/rom/mapper.rb', line 26

def header
  @header
end

#transformers ⇒ Object (readonly)

This method is part of a private API. You should avoid using this method if possible, as it may be removed or be changed in the future.

Returns transformers object built by a processor.

Returns:

  • (Object) —

    transformers object built by a processor



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# File 'lib/rom/mapper.rb', line 21

def transformers
  @transformers
end

Class Method Details

.build(header = self.header, processor = :transproc) ⇒ Mapper

This method is part of a private API. You should avoid using this method if possible, as it may be removed or be changed in the future.

Build a mapper using provided processor type

Returns:



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# File 'lib/rom/mapper.rb', line 61

def self.build(header = self.header, processor = :transproc)
  new(header, processor)
end

.headers(header) ⇒ Array<Header>

This method is part of a private API. You should avoid using this method if possible, as it may be removed or be changed in the future.

Prepares an array of headers for a potentially multistep mapper

Returns:

Raises:



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# File 'lib/rom/mapper.rb', line 50

def self.headers(header)
  return [header] if steps.empty?
  return steps.map(&:header) if attributes.empty?
  raise(MapperMisconfiguredError, "cannot mix outer attributes and steps")
end

.processors ⇒ Hash

This method is part of a private API. You should avoid using this method if possible, as it may be removed or be changed in the future.

Returns registered processors.

Returns:

  • (Hash) —

    registered processors



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# File 'lib/rom/mapper.rb', line 31

def self.processors
  @_processors ||= {}
end

.register_processor(processor) ⇒ Hash

This method is part of a private API. You should avoid using this method if possible, as it may be removed or be changed in the future.

Register a processor class

Returns:

  • (Hash) 


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# File 'lib/rom/mapper.rb', line 40

def self.register_processor(processor)
  name = processor.name.split('::').last.downcase.to_sym
  processors.update(name => processor)
end

.registry(descendants) ⇒ Object

This method is part of a private API. You should avoid using this method if possible, as it may be removed or be changed in the future. 



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# File 'lib/rom/mapper.rb', line 66

def self.registry(descendants)
  descendants.each_with_object({}) do |klass, h|
    name = klass.register_as || klass.relation
    (h[klass.base_relation] ||= {})[name] = klass.build
  end
end

Instance Method Details

#call(relation) ⇒ Object

This method is part of a private API. You should avoid using this method if possible, as it may be removed or be changed in the future.

Process a relation using the transformers



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# File 'lib/rom/mapper.rb', line 92

def call(relation)
  transformers.reduce(relation.to_a) { |a, e| e.call(a) }
end

#model ⇒ Class

This method is part of a private API. You should avoid using this method if possible, as it may be removed or be changed in the future.

Returns optional model that is instantiated by a mapper.

Returns:

  • (Class) —

    optional model that is instantiated by a mapper



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# File 'lib/rom/mapper.rb', line 85

def model
  header.model
end