DEFINE FUNCTION

DEFINE FUNCTION statement

The DEFINE FUNCTION statement allows you to define custom functions that can be reused throughout a database.

Requirements

• You must be authenticated as a root or namespace user before you can use the DEFINE FUNCTION statement.
• You must select your namespace and database before you can use the DEFINE FUNCTION statement.

Statement syntax

SurrealQL Syntax

DEFINE FUNCTION fn::@name(
    [ @argument: @type ... ]
) {
    [ @query ... ]
    [ RETURN @returned ]
}

Example usage

Below shows how you can define a custom function using the DEFINE FUNCTION statement, and how to call it.

-- It is necessary to prefix the name of your function with "fn::"
-- This indicates that it's a custom function
DEFINE FUNCTION fn::greet($name: string) {
    RETURN "Hello, " + $name + "!";
}

-- Returns: "Hello, Tobie!"
RETURN fn::greet("Tobie");

To showcase a slightly more complex custom function, this will check if a relation between two nodes exists:

DEFINE FUNCTION fn::relation_exists(
    $in: record,
    $tb: string,
    $out: record
) {
    LET $results = SELECT VALUE id FROM type::table($tb) WHERE in = $in AND out = $out;
    RETURN array::len($results) > 0;
};