Class: DataMapper::Adapters::InMemoryAdapter

Inherits:
AbstractAdapter show all
Defined in:
lib/dm-core/adapters/in_memory_adapter.rb

Overview

This is probably the simplest functional adapter possible. It simply stores and queries from a hash containing the model classes as keys, and an array of hashes. It is not persistent whatsoever; when the Ruby process finishes, everything that was stored it lost. However, it doesn’t require any other external libraries, such as data_objects, so it is ideal for writing specs against. It also serves as an excellent example for budding adapter developers, so it is critical that it remains well documented and up to date.

Instance Attribute Summary

Attributes inherited from AbstractAdapter

#field_naming_convention, #name, #options, #resource_naming_convention

Instance Method Summary collapse

Methods included from Equalizer

#equalize

Instance Method Details

#create(resources) ⇒ Object

Used by DataMapper to put records into a data-store: “INSERT” in SQL-speak. It takes an array of the resources (model instances) to be saved. Resources each have a key that can be used to quickly look them up later without searching, if the adapter supports it.



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# File 'lib/dm-core/adapters/in_memory_adapter.rb', line 21

def create(resources)
  records = records_for(resources.first.model)

  resources.each do |resource|
    initialize_serial(resource, records.size.succ)
    records << resource.attributes(:field)
  end
end

#delete(collection) ⇒ Integer

Destroys all the records matching the given query. “DELETE” in SQL.



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# File 'lib/dm-core/adapters/in_memory_adapter.rb', line 70

def delete(collection)
  records = records_for(collection.model)
  records_to_delete = collection.query.filter_records(records.dup)
  records.replace(records - records_to_delete)
  records_to_delete.size
end

#read(query) ⇒ Array

Looks up one record or a collection of records from the data-store: “SELECT” in SQL.



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# File 'lib/dm-core/adapters/in_memory_adapter.rb', line 41

def read(query)
  query.filter_records(records_for(query.model).dup)
end

#update(attributes, collection) ⇒ Object

Used by DataMapper to update the attributes on existing records in a data-store: “UPDATE” in SQL-speak. It takes a hash of the attributes to update with, as well as a collection object that specifies which resources should be updated.



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# File 'lib/dm-core/adapters/in_memory_adapter.rb', line 56

def update(attributes, collection)
  attributes = attributes_as_fields(attributes)
  read(collection.query).each { |resource| resource.update(attributes) }.size
end