9.2 Function libraries

A function library groups related functions under a namespace imported by scripts. Define functions as Java methods or register a Map<String, Udf>.

Implement a library

Extend AbstractUdfSource and use @UdfName for script-visible names. This example converts text case.

TextFunctions.java

package com.example.dataway;

import java.util.Locale;
import net.hasor.dataql.host.function.AbstractUdfSource;
import net.hasor.dataql.host.function.UdfName;

public class TextFunctions extends AbstractUdfSource {
    @UdfName("upper")
    public String upper(String value) {
        return value.toUpperCase(Locale.ROOT);
    }

    @UdfName("lower")
    public String lower(String value) {
        return value.toLowerCase(Locale.ROOT);
    }
}

Register the library

config is the application’s DatawayConfig; apply these settings before creating Dataway.

import com.example.dataway.TextFunctions;

config.importSource("app.text", TextFunctions::new);

This stateless implementation has a no-argument constructor. AbstractUdfSource creates method targets by reflection by default. Use Application imports to expose data such as application settings directly to scripts.

Call from a script

import 'app.text' as text;
return {
    'upper': text.upper('Dataway'),
    'lower': text.lower('Dataway')
};

Returns {"upper":"DATAWAY","lower":"dataway"}.

Register a function Map

import java.util.Map;
import com.example.dataway.GreetingUdf;

config.library("app.tools", Map.of("greeting", new GreetingUdf()));

import 'app.tools' as tools;
return tools.greeting('Dataway');

See Custom functions for GreetingUdf. library copies the Map during configuration; later Map changes do not alter registered functions. Method-based functions do not support overloading; use distinct names.