Class: ActiveTriples::ParentStrategy

Inherits:
Object
  • Object
show all
Includes:
PersistenceStrategy
Defined in:
lib/active_triples/persistence_strategies/parent_strategy.rb

Overview

Persistence strategy for projecting ‘RDFSource`s onto the graph of an owning parent source. This allows individual resources to be treated as within the scope of another `RDFSource`.

Defined Under Namespace

Classes: Ancestors, NilParentError, UnmutableParentError

Instance Attribute Summary collapse

Instance Method Summary collapse

Methods included from PersistenceStrategy

#destroyed?

Constructor Details

#initialize(source) ⇒ ParentStrategy

Returns a new instance of ParentStrategy.

Parameters:

  • source (RDFSource, RDF::Enumerable) —

    the ‘RDFSource` (or other `RDF::Enumerable` to persist with the strategy.



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# File 'lib/active_triples/persistence_strategies/parent_strategy.rb', line 21

def initialize(source)
  @graph  = source.graph
  @source = source
end

Instance Attribute Details

#parent ⇒ Object

Returns the value of attribute parent.



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# File 'lib/active_triples/persistence_strategies/parent_strategy.rb', line 16

attr_reader :source, :parent

#source ⇒ Object (readonly)

the source to persist with this strategy



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# File 'lib/active_triples/persistence_strategies/parent_strategy.rb', line 16

def source
  @source
end

Instance Method Details

#ancestors ⇒ Enumerator<RDFSource>

Returns:



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# File 'lib/active_triples/persistence_strategies/parent_strategy.rb', line 76

def ancestors
  Ancestors.new(source).to_enum
end

#destroy ⇒ Object

Destroys the resource by removing it graph and references from the parent.

See Also:



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# File 'lib/active_triples/persistence_strategies/parent_strategy.rb', line 61

def destroy
  super do
    graph.delete  [source.to_term, nil, nil]
    parent.delete [parent, nil, source.to_term]
  end
end

#erase_old_resource ⇒ Object

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.



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# File 'lib/active_triples/persistence_strategies/parent_strategy.rb', line 72

def erase_old_resource; end

#final_parent ⇒ #persist!

Returns the last parent in a chain from ‘parent` (e.g. the parent’s parent’s parent). This is the RDF::Mutable that the resource will project itself on when persisting.

Returns:

  • (#persist!) —

    the last parent in a chain from ‘parent` (e.g. the parent’s parent’s parent). This is the RDF::Mutable that the resource will project itself on when persisting.



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# File 'lib/active_triples/persistence_strategies/parent_strategy.rb', line 84

def final_parent
  ancestors.to_a.last
end

#graph ⇒ ActiveTriples::BufferedTransaction

Returns a transaction on parent with buffered changes, with reads projected against an “Extended Bounded Description” of the strategy’s ‘#source`.

Returns:

  • (ActiveTriples::BufferedTransaction) —

    a transaction on parent with buffered changes, with reads projected against an “Extended Bounded Description” of the strategy’s ‘#source`.

See Also:



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# File 'lib/active_triples/persistence_strategies/parent_strategy.rb', line 41

def graph
  @graph ||= BufferedTransaction.begin(parent,
                                       mutable:   true,
                                       subject:   source.to_term)
end

#graph=(graph) ⇒ Object

See Also:

  • PeristenceStrategy#graph=


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# File 'lib/active_triples/persistence_strategies/parent_strategy.rb', line 28

def graph=(graph)
  final_parent.insert(graph || source.to_a)
  @graph = BufferedTransaction.begin(parent,
                                     mutable:   true,
                                     subject:   source.to_term)
end

#persist! ⇒ true

Persists the resource to the final parent.

Returns:

  • (true) —

    true if the save did not error

Raises:



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# File 'lib/active_triples/persistence_strategies/parent_strategy.rb', line 106

def persist!
  raise NilParentError unless parent
  return false if final_parent.frozen?

  graph.execute

  parent.persist! if
    ancestors.find { |a| a.is_a?(ActiveTriples::List::ListResource) }

  reload

  @persisted = true
end

#persisted? ⇒ Boolean

Resources using this strategy are persisted only if their parent is also persisted.

Returns:

  • (Boolean)

See Also:



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# File 'lib/active_triples/persistence_strategies/parent_strategy.rb', line 52

def persisted?
  super && parent.persisted?
end

#reload ⇒ Boolean

Repopulates the graph from parent.

Returns:

  • (Boolean) 


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# File 'lib/active_triples/persistence_strategies/parent_strategy.rb', line 124

def reload
  return false if source.frozen?

  final_parent.persistence_strategy.class.new(source).reload
  self.graph = source.to_a

  @persisted = true unless graph.empty?

  true
end