Module: ActiveTriples::PersistenceStrategy Abstract

Included in:
ParentStrategy, RepositoryStrategy
Defined in:
lib/active_triples/persistence_strategies/persistence_strategy.rb

Overview

This module is abstract.

defines the basic interface for persistence of RDFSource‘s.

A PersistenceStrategy has an underlying resource which should be an RDFSource or equivalent. Strategies can be injected into RDFSource instances at runtime to change the target datastore, repository, or object the instance syncs its graph with on save and reload operations.

Examples:

Changing a PersistenceStrategy at runtime

source = ActiveTriples::Resource.new
source.persistence_strategy # => #<ActiveTriples::RepositoryStrategy:...>

source.set_persistence_strategy(MyStrategy)
source.persistence_strategy # => #<ActiveTriples::MyStrategy:...>

Instance Method Summary collapse

Instance Method Details

#destroy { ... } ⇒ Boolean Also known as: destroy!

Deletes the resource from the datastore / repository.

Yields:

  • prior to persisting, yields to allow a block that performs deletions in the persisted graph(s).

Returns:

  • (Boolean) —

    true if the resource was sucessfully destroyed



25
26
27
28
29
30
 
# File 'lib/active_triples/persistence_strategies/persistence_strategy.rb', line 25

def destroy(&block)
  yield if block_given?

  persist!
  @destroyed = true
end

#destroyed? ⇒ true, false

Indicates if the Resource has been destroyed.

Returns:

  • (true, false) 


37
38
39
 
# File 'lib/active_triples/persistence_strategies/persistence_strategy.rb', line 37

def destroyed?
  @destroyed ||= false
end

#erase_old_resource ⇒ Boolean

This method is abstract.

Clear out any old assertions in the datastore / repository

about this node or statement thus preparing to receive the updated assertions.

Returns:

  • (Boolean)

Raises:

  • (NotImplementedError) 


79
80
81
82
 
# File 'lib/active_triples/persistence_strategies/persistence_strategy.rb', line 79

def erase_old_resource
  raise NotImplementedError, 
        'Abstract method #erase_old_resource is unimplemented'
end

#graph ⇒ RDF::Graph

Returns:

  • (RDF::Graph) 


69
70
71
 
# File 'lib/active_triples/persistence_strategies/persistence_strategy.rb', line 69

def graph
  @graph ||= RDF::Graph.new
end

#graph=(graph) ⇒ RDF::Graph

Parameters:

  • graph (RDF::Graph)

Returns:

  • (RDF::Graph) 


63
64
65
 
# File 'lib/active_triples/persistence_strategies/persistence_strategy.rb', line 63

def graph=(graph)
  @graph = graph
end

#persist! ⇒ true

This method is abstract.

save the resource according to the strategy and set the @persisted flag to true

Returns true if the save did not error.

Returns:

  • (true) —

    true if the save did not error

Raises:

  • (NotImplementedError)

See Also:



56
57
58
 
# File 'lib/active_triples/persistence_strategies/persistence_strategy.rb', line 56

def persist!
  raise NotImplementedError, 'Abstract method #persist! is unimplemented'
end

#persisted? ⇒ Boolean

Indicates if the resource is persisted to the datastore / repository

Returns:

  • (Boolean) —

    true if persisted; else false.



45
46
47
 
# File 'lib/active_triples/persistence_strategies/persistence_strategy.rb', line 45

def persisted?
  @persisted ||= false
end

#reload ⇒ Boolean

This method is abstract.

Repopulate the in-memory graph from the persisted graph

Returns:

  • (Boolean)

Raises:

  • (NotImplementedError) 


88
89
90
 
# File 'lib/active_triples/persistence_strategies/persistence_strategy.rb', line 88

def reload
  raise NotImplementedError, 'Abstract method #reload is unimplemented'
end