Register a new scalar or aggregate function for use with Query of Query.
Functions only need to be registered once per runtime and they will be cached in memory until the runtime restarts.
QueryRegisterFunction(name=[string], function=[function], returnType=[string], type=[string])name
string
true
The name of the function to register without parenthesis. You will reference it in your SQL with this name.
function
function
true
The function to register. This can be a closure or a function reference. For scalar functions, the function will receive a value for each incoming argument and must return a single value. For aggregate functions, the function will receive a value for each incoming argument in the form of an array of values representing each row being aggregated and must return a single value. Null values are not passed into aggregates. Aggregate functions should return a scalar value so the size of the array won't necessarily match the number of rows in the query, and may be different across columns.
returnType
string
true
The return type of the function as a query column type. Default is "Object". This can be any valid query column type. This can be used to enforce how the return values of this function are handled. For example, customFunc() + customFunc2() will behave differently based on whether the custom functions return strings or numbers.
Object
type
string
true
The type of function to register. This can be "scalar" or "aggregate". Default is "scalar".
scalar
queryRegisterFunction( "doubleIt", ( value ) => value * 2 );
q = queryNew( "n", "integer", [ [ 5 ], [ 10 ] ] );
result = q.map( ( row ) => doubleIt( row.n ) );
writeOutput( result[ 1 ] );
Result: 10
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