Module: Neo4j::Cypher::Context::Returnable

Defined in:
lib/neo4j-cypher/context.rb

Instance Method Summary collapse

Instance Method Details

#extract(&block) ⇒ Object

To return a single property, or the value of a function from a collection of nodes or relationships, you can use EXTRACT. It will go through a collection, run an expression on every element, and return the results in an collection with these values. It works like the map method in functional languages such as Lisp and Scala. Will generate:

EXTRACT( identifier in collection : expression )



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# File 'lib/neo4j-cypher/context.rb', line 137

def extract(&block)
  Collection.new(clause_list, 'extract', self, &block).eval_context
end

#filter(&block) ⇒ Object

Returns all the elements in a collection that comply to a predicate. Will generate

FILTER(identifier in collection : predicate)



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# File 'lib/neo4j-cypher/context.rb', line 144

def filter(&block)
  Collection.new(clause_list, 'filter', self, &block).eval_context
end

#foreach(&block) ⇒ Object 



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# File 'lib/neo4j-cypher/context.rb', line 148

def foreach(&block)
  Foreach.new(clause_list, self, &block).eval_context
end

#ret(*returns, &block) ⇒ ReturnItem

Specifies a return statement. Notice that this is not needed, since the last value of the DSL block will be converted into one or more return statements.

Parameters:

  • returns (Symbol, #var_name) —

    a list of variables we want to return

Returns:



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# File 'lib/neo4j-cypher/context.rb', line 124

def ret(*returns, &block)
  options = returns.last.is_a?(Hash) ? returns.pop : {}
  returns = [self] if returns.empty? # return self unless not specified what to return
  returns = [RootClause::EvalContext.new(self).instance_exec(self, &block)].flatten if block
  r = Return.new(clause_list, returns, options, &block).eval_context
  (self.is_a?(RootClause::EvalContext)) ? r : self
end