Module: Neo4j::ActiveNode::QueryMethods

Included in:
Labels::ClassMethods
Defined in:
lib/neo4j/active_node/query_methods.rb

Instance Method Summary collapse

Instance Method Details

#count(distinct = nil) ⇒ Integer Also known as: size, length

Returns number of nodes of this class.

Returns:

  • (Integer) —

    number of nodes of this class



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# File 'lib/neo4j/active_node/query_methods.rb', line 24

def count(distinct = nil)
  fail(Neo4j::InvalidParameterError, ':count accepts `distinct` or nil as a parameter') unless distinct.nil? || distinct == :distinct
  q = distinct.nil? ? 'n' : 'DISTINCT n'
  self.query_as(:n).return("count(#{q}) AS count").first.count
end

#empty? ⇒ Boolean Also known as: blank?

Returns:



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# File 'lib/neo4j/active_node/query_methods.rb', line 33

def empty?
  !self.all.exists?
end

#exists?(node_condition = nil) ⇒ Boolean

Returns:



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# File 'lib/neo4j/active_node/query_methods.rb', line 4

def exists?(node_condition = nil)
  unless node_condition.is_a?(Integer) || node_condition.is_a?(Hash) || node_condition.nil?
    fail(Neo4j::InvalidParameterError, ':exists? only accepts ids or conditions')
  end
  query_start = exists_query_start(node_condition)
  start_q = query_start.respond_to?(:query_as) ? query_start.query_as(:n) : query_start
  start_q.return('COUNT(n) AS count').first.count > 0
end

#find_each(options = {}) ⇒ Object 



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# File 'lib/neo4j/active_node/query_methods.rb', line 45

def find_each(options = {})
  self.query_as(:n).return(:n).find_each(:n, primary_key, options) do |batch|
    yield batch.n
  end
end

#find_in_batches(options = {}) ⇒ Object 



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# File 'lib/neo4j/active_node/query_methods.rb', line 39

def find_in_batches(options = {})
  self.query_as(:n).return(:n).find_in_batches(:n, primary_key, options) do |batch|
    yield batch.map(&:n)
  end
end

#first ⇒ Object

Returns the first node of this class, sorted by ID. Note that this may not be the first node created since Neo4j recycles IDs.



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# File 'lib/neo4j/active_node/query_methods.rb', line 14

def first
  self.query_as(:n).limit(1).order(n: primary_key).pluck(:n).first
end

#last ⇒ Object

Returns the last node of this class, sorted by ID. Note that this may not be the first node created since Neo4j recycles IDs.



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# File 'lib/neo4j/active_node/query_methods.rb', line 19

def last
  self.query_as(:n).limit(1).order(n: {primary_key => :desc}).pluck(:n).first
end