Module: Hold::IdentitySetRepository

Includes:
SetRepository
Included in:
Hold::InMemory::IdentitySetRepository, Sequel::IdentitySetRepository, Sequel::PolymorphicRepository, Serialized::IdentitySetRepository
Defined in:
lib/hold/interfaces/identity_set_repository.rb

Overview

A special kind of SetRepository which stores Objects whose identities are determined by an identity property, and supports indexed lookup by their id.

May allocate the IDs itself, or not.

Exposes a somewhat more familiar CRUD-style persistence interface as a result.

Comes with default implementations for most of the extra interface

Defined Under Namespace

Classes: IdCell

Instance Method Summary collapse

Methods included from SetRepository

#can_get_class?, #can_set_class?, #contains?, #delete, #get_all, #store, #store_new

Instance Method Details

#allocates_ids? ⇒ Boolean

Either the repository allocates IDs, and you don’t (in which case any entity with an ID may be assumed to be already persisted in the repo), or the repository doesn’t allocate IDs (in which case you must always supply one when persisting a new object).

If you allocates_ids?, you should deal with an object without an identity as an argument to store and store_new, and you should set the id property on it before returning it.

If you don’t, you may raise MissingIdentity if passed an object without one.

Returns:

  • (Boolean) 


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# File 'lib/hold/interfaces/identity_set_repository.rb', line 26

def allocates_ids?
  false
end

#cell(object) ⇒ Object 



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# File 'lib/hold/interfaces/identity_set_repository.rb', line 88

def cell(object)
  id = object.id or raise MissingIdentity
  id_cell(id)
end

#contains_id?(id) ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/hold/interfaces/identity_set_repository.rb', line 75

def contains_id?(id)
  !!get_by_id(id)
end

#delete_id(id) ⇒ Object

deletes the object with the given identity where it exists in the repo



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# File 'lib/hold/interfaces/identity_set_repository.rb', line 36

def delete_id(id)
  delete(get_by_id(id))
end

#get_by_id(id) ⇒ Object

Looks up a persisted object by the value of its identity property

Raises:



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# File 'lib/hold/interfaces/identity_set_repository.rb', line 31

def get_by_id(id)
  raise UnsupportedOperation
end

#get_many_by_ids(ids) ⇒ Object 



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# File 'lib/hold/interfaces/identity_set_repository.rb', line 80

def get_many_by_ids(ids)
  ids.map {|id| get_by_id(id)}
end

#id_cell(id) ⇒ Object 



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# File 'lib/hold/interfaces/identity_set_repository.rb', line 84

def id_cell(id)
  IdCell.new(self, id)
end

#load(object) ⇒ Object

Like reload, but updates the given instance in-place with the updated data. Returns nil where the object is no longer present in the repository

Raises:



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# File 'lib/hold/interfaces/identity_set_repository.rb', line 50

def load(object)
  raise UnsupportedOperation unless object.respond_to?(:merge!)
  updated = reload(object) or return
  object.merge!(updated)
  object
end

#reload(object) ⇒ Object

Loads a fresh instance of the given object by its id Returns nil where the object is no longer present in the repository



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# File 'lib/hold/interfaces/identity_set_repository.rb', line 42

def reload(object)
  id = object.id or raise MissingIdentity
  get_by_id(id)
end

#update(entity, update_entity) ⇒ Object

Applies an in-place update to the object, where it exists in the repository

Raises:



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# File 'lib/hold/interfaces/identity_set_repository.rb', line 59

def update(entity, update_entity)
  raise UnsupportedOperation unless entity.respond_to?(:merge!)
  load(entity) or return
  entity.merge!(update_entity)
  store(entity)
end

#update_by_id(id, update_entity) ⇒ Object

Applies an in-place update to the object with the given identity, where it exists in the repository

Raises:



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# File 'lib/hold/interfaces/identity_set_repository.rb', line 68

def update_by_id(id, update_entity)
  entity = get_by_id(id) or return
  raise UnsupportedOperation unless entity.respond_to?(:merge!)
  entity.merge!(update_entity)
  store(entity)
end