Class: DmAdapterSimpledb::Record

Inherits:
Object
  • Object
show all
Includes:
Utils
Defined in:
lib/dm-adapter-simpledb/record.rb

Direct Known Subclasses

RecordV0, RecordV1_1

Constant Summary collapse

METADATA_KEY = 
"__dm_metadata"
STORAGE_NAME_KEY = 
"simpledb_type"
META_KEYS = 
[METADATA_KEY, STORAGE_NAME_KEY]
CURRENT_VERSION = 
"01.01.00"

Instance Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Methods included from Utils

#transform_hash

Constructor Details

#initialize(hash_or_resource) ⇒ Record

Returns a new instance of Record.



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# File 'lib/dm-adapter-simpledb/record.rb', line 64

def initialize(hash_or_resource)
  case hash_or_resource
  when DataMapper::Resource then
    attrs_to_update, attrs_to_delete = extract_attributes(hash_or_resource)
    @simpledb_attributes  = attrs_to_update
    @deletable_attributes = attrs_to_delete
    @item_name = item_name_for_resource(hash_or_resource)
    @model = hash_or_resource.model
  when Hash
    hash = hash_or_resource
    @item_name = hash.keys.first
    @simpledb_attributes  = hash.values.first
    @deletable_attributes = []
  else
    raise "Don't know how to initialize from #{hash_or_resource.inspect}"
  end
end

Instance Attribute Details

#deletable_attributes ⇒ Object

Returns the value of attribute deletable_attributes.



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# File 'lib/dm-adapter-simpledb/record.rb', line 60

def deletable_attributes
  @deletable_attributes
end

#item_name ⇒ Object

Returns the value of attribute item_name.



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# File 'lib/dm-adapter-simpledb/record.rb', line 61

def item_name
  @item_name
end

#simpledb_attributes ⇒ Object Also known as: writable_attributes

Returns the value of attribute simpledb_attributes.



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# File 'lib/dm-adapter-simpledb/record.rb', line 59

def simpledb_attributes
  @simpledb_attributes
end

Class Method Details

.data_version(simpledb_attributes) ⇒ Object 



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# File 'lib/dm-adapter-simpledb/record.rb', line 47

def self.data_version(simpledb_attributes)
  simpledb_attributes.fetch(METADATA_KEY){[]}.grep(/v\d\d\.\d\d\.\d\d/) do 
    |version_stamp|
    return version_stamp[1..-1]
  end
  return "00.00.00"
end

.from_resource(resource) ⇒ Object 



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# File 'lib/dm-adapter-simpledb/record.rb', line 26

def self.from_resource(resource)
  versions.fetch(CURRENT_VERSION).new(resource)
end

.from_simpledb_hash(hash) ⇒ Object 



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# File 'lib/dm-adapter-simpledb/record.rb', line 19

def self.from_simpledb_hash(hash)
  data_version = data_version(simpledb_attributes(hash))
  versions.fetch(data_version) do
    raise "Unknown data version for: #{hash.inspect}"
  end.new(hash)
end

.register(klass, version) ⇒ Object 



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# File 'lib/dm-adapter-simpledb/record.rb', line 30

def self.register(klass, version)
  versions[version] = klass
end

.simpledb_attributes(hash) ⇒ Object 



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# File 'lib/dm-adapter-simpledb/record.rb', line 55

def self.simpledb_attributes(hash)
  hash.values.first
end

.version(version = nil) ⇒ Object 



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# File 'lib/dm-adapter-simpledb/record.rb', line 38

def self.version(version=nil)
  if version
    Record.register(self, version)
    @version = version
  else
    @version
  end
end

.versions ⇒ Object 



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# File 'lib/dm-adapter-simpledb/record.rb', line 34

def self.versions
  @versions ||= {}
end

Instance Method Details

#[](attribute, type) ⇒ Object 



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# File 'lib/dm-adapter-simpledb/record.rb', line 98

def [](attribute, type)
  values = Array(simpledb_attributes[attribute])
  coerce_to(values, type)
end

#add_metadata_to!(hash, table_name) ⇒ Object 



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# File 'lib/dm-adapter-simpledb/record.rb', line 183

def add_metadata_to!(hash, table_name)
  hash.merge!({
      STORAGE_NAME_KEY => [table_name],
      METADATA_KEY     => [version_token, Table.token_for(table_name)]
    })
end

#coerce_to(values, type_or_property) ⇒ Object 



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# File 'lib/dm-adapter-simpledb/record.rb', line 103

def coerce_to(values, type_or_property)
  case type_or_property
  when DataMapper::Property
    coerce_to_property(values, type_or_property)
  when Class
    coerce_to_type(values, type_or_property)
  else raise "Should never get here"
  end
end

#coerce_to_property(value, property) ⇒ Object 



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# File 'lib/dm-adapter-simpledb/record.rb', line 113

def coerce_to_property(value, property)
  property.typecast(coerce_to_type(value, property.type))
end

#coerce_to_type(values, type) ⇒ Object 



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# File 'lib/dm-adapter-simpledb/record.rb', line 117

def coerce_to_type(values, type)
  case 
  when type <= String
    case values.size
    when 0
      nil
    when 1
      values.first
    else
      ChunkedString.new(values)
    end
  when type <= Array, type <= DataMapper::Types::SdbArray
    values
  else
    values.first
  end
end

#metadata ⇒ Object 



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# File 'lib/dm-adapter-simpledb/record.rb', line 156

def metadata
  simpledb_attributes[METADATA_KEY]
end

#migrate ⇒ Object

Returns a record of the current version



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# File 'lib/dm-adapter-simpledb/record.rb', line 161

def migrate
  new_record = Record.versions[CURRENT_VERSION].allocate
  new_record.item_name = item_name
  data = transform_hash(simpledb_attributes) {
    |hash, key, values|
    hash[key] = coerce_heuristically(values)
  }
  updates = {}
  deletes = []
  data.each_pair do |key, values|
    if Array(values).empty?
      deletes << key
    else
      updates[key] = values
    end
  end
  new_record.add_metadata_to!(updates, table)
  new_record.simpledb_attributes = updates
  new_record.deletable_attributes = deletes
  new_record
end

#storage_name ⇒ Object

Deprecated - we are moving the type information under the metadata key



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# File 'lib/dm-adapter-simpledb/record.rb', line 94

def storage_name
  simpledb_attributes[STORAGE_NAME_KEY].first
end

#table ⇒ Object

Returns the “Table” this record belongs to. SimpleDB has no concept of tables, but we fake it with metadata.



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# File 'lib/dm-adapter-simpledb/record.rb', line 145

def table
  table_name_from_model || Table.name_from_metadata(metadata) || 
    storage_name
end

#table_name_from_model(repository = DataMapper.repository.name) ⇒ Object 



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# File 'lib/dm-adapter-simpledb/record.rb', line 150

def table_name_from_model(repository=DataMapper.repository.name)
  if defined?(@model) && @model
    @model.storage_name(repository)
  end
end

#to_resource_hash(fields) ⇒ Object

Convert to a Hash suitable for initializing a Resource

Parameters:

  • fields (PropertySet) —

    The fields to extract



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# File 'lib/dm-adapter-simpledb/record.rb', line 86

def to_resource_hash(fields)
  result = transform_hash(fields) {|hash, property|
    hash[property.name.to_s] = self[property.field, property]
  }
  result
end

#version ⇒ Object 



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# File 'lib/dm-adapter-simpledb/record.rb', line 135

def version
  self.class.version || self.class.data_version(simpledb_attributes)
end

#version_token ⇒ Object 



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# File 'lib/dm-adapter-simpledb/record.rb', line 139

def version_token
  "v#{version}"
end