7.6 Conversion functions

Module dependency

Provided by dataql-engine. Import net.hasor.dataql.host.function.basic.ConvertUdfSource to use this library.

Convert values to numbers, strings, booleans or binary data. Each example runs independently. Square brackets in signatures denote optional parameters.

toInt

convert.toInt(target) accepts a number or numeric string and returns a number, preserving fractions. null, blank strings and other types return 0; invalid numeric strings throw an error.

import 'net.hasor.dataql.host.function.basic.ConvertUdfSource' as convert;
return [convert.toInt('12.5'), convert.toInt('42'), convert.toInt(null), convert.toInt(' ')];

Returns [12.5, 42, 0, 0].

toString

convert.toString(target) returns a string representation; null becomes the string "null". Use json.toJson for JSON objects.

import 'net.hasor.dataql.host.function.basic.ConvertUdfSource' as convert;
return [convert.toString(12), convert.toString(true), convert.toString(null)];

Returns ["12", "true", "null"].

toBoolean

convert.toBoolean(target) preserves booleans and accepts case-insensitive boolean strings including true/false, on/off and yes/no. Unrecognized strings return null; null, numbers and other types return false.

import 'net.hasor.dataql.host.function.basic.ConvertUdfSource' as convert;
return [convert.toBoolean('ON'), convert.toBoolean('off'),
        convert.toBoolean('blue'), convert.toBoolean(null), convert.toBoolean(1)];

Returns [true, false, null, false, false].

textToByte

convert.textToByte(text[, charset]) encodes a string as binary data. charset is a charset name and defaults to UTF-8. Null and empty strings produce empty binary values.

import 'net.hasor.dataql.host.function.basic.ConvertUdfSource' as convert;
var content = convert.textToByte('你好', 'UTF-16LE');
return {'hex': convert.byteToHex(content), 'text': convert.byteToString(content, 'UTF-16LE')};

Returns {"hex":"604F7D59","text":"你好"}. Pass binary values directly to other functions; this example decodes them to show their contents.

stringToByte

convert.stringToByte(text[, charset]) returns binary data with the same behavior as textToByte.

import 'net.hasor.dataql.host.function.basic.ConvertUdfSource' as convert;
return convert.byteToHex(convert.stringToByte('AB'));

Returns "4142".

hexToByte

convert.hexToByte(text) parses an even-length hexadecimal string as binary data. Hex letters are case-insensitive. Null returns null; an empty string returns empty binary data.

import 'net.hasor.dataql.host.function.basic.ConvertUdfSource' as convert;
return convert.byteToHex(convert.hexToByte('007fff'));

Returns "007FFF".

byteToHex

convert.byteToHex(content) returns uppercase hex from binary data or a numeric byte list. Null returns null; empty content returns an empty string.

import 'net.hasor.dataql.host.function.basic.ConvertUdfSource' as convert;
return [convert.byteToHex([0, 127, -1]), convert.byteToHex([]), convert.byteToHex(null)];

Returns ["007FFF", "", null]. Numbers are converted to signed bytes; for example, -1 becomes FF.

byteToString

convert.byteToString(content[, charset]) decodes binary data or a numeric byte list. The charset defaults to UTF-8. Null returns null; empty content returns an empty string.

import 'net.hasor.dataql.host.function.basic.ConvertUdfSource' as convert;
return [convert.byteToString([65, 66]), convert.byteToString([]), convert.byteToString(null)];

Returns ["AB", "", null].

Binary reads close the stream they open. In-memory bytes support repeated reads; a single-use stream can be consumed only once. Uploaded temporary files are cleaned up after the request. See Binary responses for HTTP output.