Module: Tripod::EagerLoading

Extended by:
ActiveSupport::Concern
Included in:
Components
Defined in:
lib/tripod/eager_loading.rb

Instance Attribute Summary collapse

Instance Method Summary collapse

Instance Attribute Details

#object_resources ⇒ Object (readonly)

array of resources that represent the objects of the triples of this resource



9
10
11
 
# File 'lib/tripod/eager_loading.rb', line 9

def object_resources
  @object_resources
end

#predicate_resources ⇒ Object (readonly)

array of resources that represent the predicates of the triples of this resource



6
7
8
 
# File 'lib/tripod/eager_loading.rb', line 6

def predicate_resources
  @predicate_resources
end

Instance Method Details

#build_multifield_query(predicates, subject_position_as) ⇒ Object

build a list of optional predicates

for the input 

build_multifield_query(RDF::SKOS.prefLabel, RDF::RDFS.label, RDF::DC.title],"?p")

the follwing query is generated

CONSTRUCT {

?p <http://www.w3.org/2004/02/skos/core#prefLabel> ?pref_label . 
?p <http://www.w3.org/2000/01/rdf-schema#label> ?label . 
?p <http://purl.org/dc/elements/1.1/title> ?title . }
WHERE {  
  <http://data.hampshirehub.net/data/miscelleanous/2011-census-ks101ew-usual-resident-population-key-statistics-ks> ?p ?o .  
  OPTIONAL { ?p <http://www.w3.org/2004/02/skos/core#prefLabel> ?pref_label .  } 
  OPTIONAL { ?p <http://www.w3.org/2000/01/rdf-schema#label> ?label .  }
  OPTIONAL { ?p <http://purl.org/dc/elements/1.1/title> ?title .  } 
}



66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
 
# File 'lib/tripod/eager_loading.rb', line 66

def build_multifield_query(predicates,subject_position_as)
    clauses = []

    iter = 0
    predicates.each do |p|
      variable_name = "var#{iter.to_s}"
      clauses << "#{subject_position_as} <#{p.to_s}> ?#{variable_name} . "   
      iter +=1   
    end

    construct_query = "CONSTRUCT { "
    clauses.each do |c|
      construct_query += c
    end

    construct_query += " } WHERE {  <#{self.uri.to_s}> ?p ?o . "
    clauses.each do |c|
      construct_query += " OPTIONAL { #{c} } "
    end
    construct_query += " }" # close WHERE
end

#eager_load_object_triples!(opts = {}) ⇒ Object

get all the triples in the db where the object uri is their subject stick the results in this resource’s repo options: labels_only (default false) options: predicates (default nil) array of predicaets (as URIs or strings representing URIs) for fieldnames to fetch



33
34
35
36
37
38
39
40
41
42
43
44
45
46
 
# File 'lib/tripod/eager_loading.rb', line 33

def eager_load_object_triples!(opts={})
  object_uris = []

  if opts[:labels_only]
    construct_query = "CONSTRUCT { ?o <#{RDF::RDFS.label}> ?obj_label } WHERE { <#{self.uri.to_s}> ?p ?o . ?o <#{RDF::RDFS.label}> ?obj_label }"
  elsif (opts[:predicates] && opts[:predicates].length > 0)      
    construct_query = build_multifield_query(opts[:predicates],"?o")
  else
    construct_query = "CONSTRUCT { ?o ?obj_pred ?obj_label } WHERE { <#{self.uri.to_s}> ?p ?o . ?o ?obj_pred ?obj_label }"
  end

  extra_triples = self.class._graph_of_triples_from_construct_or_describe construct_query
  self.class.add_data_to_repository(extra_triples, self.repository)
end

#eager_load_predicate_triples!(opts = {}) ⇒ Object

get all the triples in the db where the predicate uri is their subject stick the results in this resource’s repo options: labels_only (default false) options: predicates (default nil) array of predicaets (as URIs or strings representing URIs) for fieldnames to fetch



15
16
17
18
19
20
21
22
23
24
25
26
27
 
# File 'lib/tripod/eager_loading.rb', line 15

def eager_load_predicate_triples!(opts={})

  if opts[:labels_only]
    construct_query = "CONSTRUCT { ?p <#{RDF::RDFS.label}> ?pred_label } WHERE { <#{self.uri.to_s}> ?p ?o . ?p <#{RDF::RDFS.label}> ?pred_label }"
  elsif (opts[:predicates] && opts[:predicates].length > 0)
    construct_query = build_multifield_query(opts[:predicates],"?p")
  else
    construct_query = "CONSTRUCT { ?p ?pred_pred ?pred_label } WHERE { <#{self.uri.to_s}> ?p ?o . ?p ?pred_pred ?pred_label }"
  end

  extra_triples = self.class._graph_of_triples_from_construct_or_describe construct_query
  self.class.add_data_to_repository(extra_triples, self.repository)
end

#get_related_resource(resource_uri, class_of_resource_to_create) ⇒ Object

 get the resource that represents a particular uri. If there’s triples in our repo where that uri  is the subject, use that to hydrate a resource, otherwise justdo a find against the db.



90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
 
# File 'lib/tripod/eager_loading.rb', line 90

def get_related_resource(resource_uri, class_of_resource_to_create)
  data_graph = RDF::Graph.new

  self.repository.query( [ RDF::URI.new(resource_uri.to_s), :predicate, :object] ) do |stmt|
    data_graph << stmt
  end

  if data_graph.empty?
    r = nil
  else
    # it's in our eager loaded repo
    r = class_of_resource_to_create.new(resource_uri)
    r.hydrate!(:graph => data_graph)
    r.new_record = false
    r
  end
  r
end

#has_related_resource?(resource_uri, class_of_resource) ⇒ Boolean

Returns:

  • (Boolean) 


109
110
111
 
# File 'lib/tripod/eager_loading.rb', line 109

def has_related_resource?(resource_uri, class_of_resource)
  !!get_related_resource(resource_uri, class_of_resource)
end