Module: Tripod::CriteriaExecution

Extended by:
ActiveSupport::Concern
Included in:
Criteria
Defined in:
lib/tripod/criteria/execution.rb

Overview

this module provides execution methods to a criteria object

Instance Method Summary collapse

Instance Method Details

#as_query(opts = {}) ⇒ Object

turn this criteria into a query



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# File 'lib/tripod/criteria/execution.rb', line 56

def as_query(opts={})
  Tripod.logger.debug("TRIPOD: building select query for criteria...")

  return_graph = opts.has_key?(:return_graph) ? opts[:return_graph] : true

  Tripod.logger.debug("TRIPOD: with return_graph: #{return_graph.inspect}")

  select_query = "SELECT DISTINCT ?uri "

  if return_graph
    # if we are returing the graph, select it as a variable, and include either the <graph> or ?graph in the where clause
    if graph_uri
      select_query += "(<#{graph_uri}> as ?graph) WHERE { GRAPH <#{graph_uri}> { "
    else
      select_query += "?graph WHERE { GRAPH ?graph { "
    end
  else
    select_query += "WHERE { "
    # if we're not returning the graph, only restrict by the <graph> if there's one set at class level
    select_query += "GRAPH <#{graph_uri}> { " if graph_uri
  end

  select_query += self.query_where_clauses.join(" . ")
  select_query += " } "
  select_query += "} " if return_graph || graph_uri # close the graph clause
  select_query += self.extra_clauses.join(" ")

  select_query += [order_clause, limit_clause, offset_clause].join(" ")

  select_query.strip
end

#count(opts = {}) ⇒ Object

Return how many records the current criteria would return

Parameters:

  • options (Hash) —

    a customizable set of options



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# File 'lib/tripod/criteria/execution.rb', line 43

def count(opts={})
  sq = Tripod::SparqlQuery.new(self.as_query(opts))
  count_sparql = sq.as_count_query_str
  result = Tripod::SparqlClient::Query.select(count_sparql)

  if result.length > 0
    result[0]["tripod_count_var"]["value"].to_i
  else
    return 0
  end
end

#first(opts = {}) ⇒ Object

Execute the query and return the first result as a hydrated resource

Parameters:

  • options (Hash) —

    a customizable set of options



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# File 'lib/tripod/criteria/execution.rb', line 34

def first(opts={})
  sq = Tripod::SparqlQuery.new(self.as_query(opts))
  first_sparql = sq.as_first_query_str
  self.resource_class._resources_from_sparql(first_sparql).first
end

#resources(opts = {}) ⇒ Object

Execute the query and return a ResourceCollection of all hydrated resources ResourceCollection is an Enumerable, Array-like object.

Parameters:

  • options (Hash) —

    a customizable set of options



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# File 'lib/tripod/criteria/execution.rb', line 13

def resources(opts={})
  Tripod::ResourceCollection.new(
    self.resource_class._resources_from_sparql(self.as_query(opts)),
     # pass in the criteria that was used to generate this collection, as well as whether the user specified return graph
    :return_graph => (opts.has_key?(:return_graph) ? opts[:return_graph] : true),
    :criteria => self
  )
end

#serialize(opts = {}) ⇒ Object

run a query to get the raw serialisation of the results of this criteria object.

Parameters:

  • options (Hash) —

    a customizable set of options



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# File 'lib/tripod/criteria/execution.rb', line 26

def serialize(opts={})
  select_sparql = self.as_query(:return_graph => opts[:return_graph])
  self.resource_class._raw_describe_select_results(select_sparql, :accept_header => opts[:accept_header]) # note that this method defaults to using application/n-triples.
end