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 inherited from AbstractAdapter

#attributes_as_fields, descendants, inherited, #initialize_serial, #new_query

Methods included from DataMapper::Assertions

#assert_kind_of

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.

Parameters:

  • resources (Enumerable(Resource)) —

    The set of resources (model instances)



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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 << attributes_as_fields(resource.attributes(nil))
  end
end

#delete(collection) ⇒ Integer

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

Parameters:

Returns:

  • (Integer) —

    The number of records that were deleted.



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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.

Parameters:

  • query (Query) —

    The query to be used to seach for the resources

Returns:

  • (Array) —

    An Array of Hashes containing the key-value pairs for each record



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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

#reset ⇒ Object

TODO consider proper automigrate functionality



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# File 'lib/dm-core/adapters/in_memory_adapter.rb', line 78

def reset
  @records = {}
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.

Parameters:

  • attributes (Hash) —

    A set of key-value pairs of the attributes to update the resources with.

  • resources (DataMapper::Collection) —

    The collection of resources to update.



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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 { |record| record.update(attributes) }.size
end