Conditional expressions (`CASE`)

This page describes how to create CASE expressions in Cypher® with Cypher Builder.

Simple CASE

The simple CASE form compares a single expressions against multiple values. It can be constructed with the Case class by passing the expression to be compared the constructor:

const person = new Cypher.Node();
new Cypher.Case(person.property("eyes"))
    .when(new Cypher.Literal("blue")).then(new Cypher.Literal(1))
    .when(new Cypher.Literal("brown"), new Cypher.Literal("hazel")).then(new Cypher.Literal(2))
    .else(new Cypher.Literal(3))

The resulting Cypher®, note that END is added automatically:

CASE n.eyes
  WHEN 'blue'  THEN 1
  WHEN 'brown', 'hazel' THEN 2
  ELSE 3
END

Generic CASE

The generic CASE expression with conditional statements can be constructed with the Case class by ignoring the constructor parameter:

const person = new Cypher.Node();
new Cypher.Case()
    .when(Cypher.eq(person.property("eyes"), new Cypher.Literal("blue")))
    .then(new Cypher.Literal(1))
    .when(Cypher.lt(person.property("age"), new Cypher.Literal(40)))
    .then(new Cypher.Literal(2))
    .else(new Cypher.Literal(3))

The resulting Cypher®, note that END is added automatically:

CASE
  WHEN n.eyes = 'blue' THEN 1
  WHEN n.age < 40      THEN 2
  ELSE 3
END