Class: Cyrel::Expression::ExistsBlock

Inherits:
Base
  • Object
show all
Defined in:
lib/cyrel/expression/exists.rb

Overview

Represents an EXISTS { MATCH … WHERE … } subquery predicate (Memgraph 3.5+). Allows full subquery syntax inside EXISTS block.

Examples:

Cyrel.exists_block { match(Cyrel.node(:a) > Cyrel.rel(:r) > Cyrel.node(:b)); where(Cyrel.prop(:b, :active) == true) }
# => EXISTS { MATCH (a)-[r]->(b) WHERE b.active = $p1 }

Instance Attribute Summary collapse

Instance Method Summary collapse

Methods inherited from Base

#!=, #%, #&, #*, #+, #-, #/, #<, #<=, #==, #=~, #>, #>=, #^, #|

Constructor Details

#initialize(subquery) ⇒ ExistsBlock

Returns a new instance of ExistsBlock.

Parameters:

  • subquery (Cyrel::Query) —

    A query object representing the subquery.

Raises:

  • (ArgumentError) 


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# File 'lib/cyrel/expression/exists.rb', line 49

def initialize(subquery)
  raise ArgumentError, 'ExistsBlock requires a Cyrel::Query' unless subquery.is_a?(Cyrel::Query)

  @subquery = subquery
end

Instance Attribute Details

#subquery ⇒ Object (readonly)

Returns the value of attribute subquery.



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# File 'lib/cyrel/expression/exists.rb', line 46

def subquery
  @subquery
end

Instance Method Details

#render(query) ⇒ String

Renders the EXISTS { … } expression.

Parameters:

  • query (Cyrel::Query) —

    The parent query for parameter merging.

Returns:

  • (String) —

    The Cypher string fragment.



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# File 'lib/cyrel/expression/exists.rb', line 58

def render(query)
  inner_cypher, inner_params = @subquery.to_cypher

  # Merge subquery parameters into the parent query
  # The inner query uses its own parameter keys, we need to register values
  # which will get new keys in the parent query
  inner_params.each_value do |value|
    query.register_parameter(value)
  end

  "EXISTS { #{inner_cypher} }"
end