Class: ROM::Mapper

Inherits:
Object
  • Object
show all
Includes:
DSL
Defined in:
lib/rom/mapper.rb,
lib/rom/mapper/dsl.rb,
lib/rom/mapper/builder.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, Builder

Instance Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(header, processor = :transformer) ⇒ 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 78

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

Instance Attribute Details

#headerHeader (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 29

def header
  @header
end

#transformersObject (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 24

def transformers
  @transformers
end

Class Method Details

.build(header = self.header, processor = :transformer) ⇒ 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 65

def self.build(header = self.header, processor = :transformer)
  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 53

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

.processorsHash

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 34

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 43

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 70

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 96

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

#modelClass

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 89

def model
  header.model
end