apoc.custom.asFunction

Procedure APOC Full Deprecated

apoc.custom.asFunction(name, statement, outputs, inputs, forceSingle, description) - register a custom cypher function

Signature

apoc.custom.asFunction(name :: STRING?, statement :: STRING?, outputs =  :: STRING?, inputs = null :: LIST? OF LIST? OF STRING?, forceSingle = false :: BOOLEAN?, description =  :: STRING?) :: VOID

Input parameters

Name	Type	Default
name	STRING?	null
statement	STRING?	null
outputs	STRING?
inputs	LIST? OF LIST? OF STRING?	null
forceSingle	BOOLEAN?	false
description	STRING?

Name

Type

Default

name

STRING?

null

statement

STRING?

null

outputs

STRING?

inputs

LIST? OF LIST? OF STRING?

null

forceSingle

BOOLEAN?

false

description

STRING?

Usage Examples

Please note that apoc.custom.asFunction and apoc.custom.asProcedure are deprecated in favor of apoc.custom.declareFunction and apoc.custom.declareProcedure. See here for more info.

This is the list of input parameters, name and statement are mandatory fields:

Table 1. Parameters
name	default	description
`name`	`none`	dot-separated name, will be prefixed with `custom`
`statement`	`none`	cypher statement to run, can use $parameters
`outputs`	`"LIST OF MAP"`	Output type for single output, if the type is a list, then all rows will be collected, otherwise just the first row. Only single column results are allowed. If your single row result is a list you can force a single row by setting the last parameter to `true`
`inputs`	`[["params","MAP","{}"]]`	Pairs or triples of name-type-default, to be used as input parameters. The default just takes an optional map, otherwise they will become proper parameters in order
`singleRow`	`false`	If set to true, the statement is treated as single row even with the list result type, then your statement has to return a list.
`description`	`""`	A general description about the business rules implemented into the function

Given statement will be registered as a statement, the results into a single value. If the given output type is a list, results will be collected into a list, otherwise the first row will be used. The statement needs to return a single column, otherwise an error is thrown.

The type names can be the same as apoc.custom.declare* analogues.

Here is a simple example:

CALL apoc.custom.asFunction('answer','RETURN 42')

We can create the function custom.double, that doubles the provided value, by running the following function:

CALL apoc.custom.asFunction(
  'double',
  'RETURN $input*2 as answer',
  'long',
  [['input','number']]
);

We can use this function, as shown in the query below:

RETURN custom.double(12) AS value;

Table 2. Results
value
24

More documentation of apoc.custom.asFunction