Use Chance.js and Fony.js in your SQL queries😎
Tags: javascript, backend, database, sql
Published: 2023-05-03 07:01:43

## TL;DR
This post explains how to use the [Chance.js](https://www.jsdelivr.com/package/npm/chance) library and how to provide JSON template feature inspired from the [Fony.js](https://github.com/captainsafia/fony) library so that you can generate random JSON data using SQL:
```sql
select json_serialize( 
           chance.template( json {'raceId': 'natural', 
                                  'name': 'name', 
                                  'laps': 'natural', 
                                  'date': 'date', 
                                  'podium': {} } 
                          ) pretty ) as new_races;

NEW_RACES
__________________________________________
{
  "date" : "2056-11-14T13:26:53.751000Z",
  "laps" : 35,
  "name" : "Scott Wilkins",
  "podium" :
  {
  },
  "raceId" : 64315
}
```

![MLE for JavaScript](https://dev-to-uploads.s3.amazonaws.com/uploads/articles/wimzpjox05cgyfh9igak.png)
The Oracle Database has the **MultiLingual Engine** (MLE) for JavaScript built directly into the kernel since the 21c release. MLE allows running JavaScript code _inside_ the Oracle database. It is powered by the [GraalVM](https://www.graalvm.org/javascript/).

JavaScript support was first introduced in Oracle 21c specifically targeting Application Express developers, allowing them to use an additional programming languge. In Oracle 23c the feature set has been greatly expanded to include the creation of JavaScript ES Modules (ESM for ECMAScript Modules).

## Setup
_Remark: The following scripts are run on an Oracle database 23c FREE - Developer Release using sqlplus._

First things first, let's start a 23c FREE Developer Release Docker image using Podman:

```sh
# create a folder where we'll download our ES Modules
mkdir mle

# start the container
podman run -d --name oracle -e ORACLE_PASSWORD=free -p 1521:1521 \
  --mount=type=bind,src=./mle,dst=/home/oracle/mle,relabel=shared gvenzl/oracle-free:23.2.0-full
# wait a couple of seconds-minutes depending on whether it's the first time being started
```

The command will configure the SYS and SYSTEM passwords as `free` (in lower case), it will allow connecting to the FREEPDB1 pluggable database using local port 1521 and it will mount our local folder `mle` into the container as `/home/oracle/mle`.

Next, let's create a new user named developer and grant the right privileges for getting started:
```sql
-- Running these commands as SYS or SYSTEM
-- sqlplus sys/free@localhost:1521/freepdb1 as sysdba

-- create the user and grant privileges
create user developer identified by "free";
alter user developer quota unlimited on users; -- no quota issue on USERS tablespace
grant DB_DEVELOPER_ROLE to developer; -- new role to ease quick setup for developers
grant execute on javascript to developer; -- allows running JavaScript

-- create the directory to access filesystem where we'll download our ES Modules
create directory mle_dir as '/home/oracle/mle';
grant read on directory mle_dir to developer;
```

## Installing the Chance.js ES Module
For the rest of this post, we'll focus on the [Chance.js](https://www.jsdelivr.com/package/npm/chance) module from [Victor Quinn](https://www.victorquinn.com/about/) under [MIT License](https://en.wikipedia.org/wiki/MIT_License). This module is really interesting when working on data as it provides _numerous_ ways to "generate random numbers, characters, strings, names, addresses, dice, and pretty much anything else"; in brief 100+ new data generators.

The latest version available at the time of writing is 1.1.11, so let's download it into our `mle` folder so that it can be used by the database:
```sh
curl -Lo ./mle/chance.js https://cdn.jsdelivr.net/npm/chance@1.1.11/+esm
```

Now it's time to connect as our `developer` user and do the real things, connect with `sqlplus` (from inside the container or using other tools such as [SQLcl](https://download.oracle.com/otn_software/java/sqldeveloper/sqlcl-latest.zip) or [SQL Developer](https://www.oracle.com/database/sqldeveloper/technologies/download/) from outside the container):
```sh
# Run sqlplus from inside the container:
podman exec -it oracle /bin/bash

sqlplus developer/free@localhost:1521/freepdb1
```

And now connected as `developer`, run:
```sql
-- prevents variable substitution because of &
SET VERIFY OFF
-- prevents && interpretation by sqlplus
SET DEFINE OFF

-- creates the MLE module named chance_module
create or replace mle module chance_module language javascript version '1.1.11' using bfile( mle_dir, 'chance.js' );
/

-- creates the corresponding MLE environment that will help for managing depencies at runtime
create or replace mle env chance_module_env imports ('chance' module chance_module);

-- creates a new 'extended' module that will export properly the functions for future usage in PL/SQL
create or replace mle module chance_extended language javascript version '1.1.11' as
import Chance from 'chance';
const chance = new Chance();
const chanceTypes = Object.keys(Object.getPrototypeOf(chance));

// inspired from Fony
function valid(type) {
  return chanceTypes.indexOf(type) !== -1;
}

function getArrayValue(definition) {
  if (definition.length !== 2) {
    return null;
}
  const type = definition[0];
  const count = definition[1];
  if (!valid(type) || typeof count !== "number" || count === 0) {
    return null;
}
  return new Array(count).fill(null).map(function() {
    return getValue(type);
  });
}

function getValue(type) {
  if (Array.isArray(type)) {
    return getArrayValue(type);
  }
  if (typeof type === "object" && !Array.isArray(type) && type != null) {
    var result = template(type);
    return result._$_chance ? result._$_chance : result;
  }
  try {
    return chance[type]();
  } catch (exception) {
    return null;
  }
}

function template(json_template) {
  const output = {};
  Object.keys(json_template).map(function(key, index) {
    if (typeof key === "string" && key.charAt(0) === '$' && valid(key.substring(1))) {
      output['_$_chance'] = chance[key.substring(1)](json_template[key]);
    } else {
      output[key] = getValue(json_template[key]);
    }
  });
  return output;
}

chance.yearStr = chance.year;
chance.year = function (doc) { return parseInt(chance.yearStr(doc)); }

export {chance, template};

/
```

So far, we've installed the `Chance.js` module and an extended one that exports properly each of the function with a signature compatible with the Oracle database data types (including the native [JSON](https://docs.oracle.com/en/database/oracle/oracle-database/23/sqlrf/Data-Types.html#GUID-E441F541-BA31-4E8C-B7B4-D2FB8C42D0DF) and new 23c [BOOLEAN](https://docs.oracle.com/en/database/oracle/oracle-database/23/sqlrf/Data-Types.html#GUID-285FFCA8-390D-4FA9-9A51-47B84EF5F83A)).

We've also created an [MLE environment](https://docs.oracle.com/en/database/oracle/oracle-database/23/mlejs/mle-js-modules-and-environments.html#GUID-32E2D1BB-37A0-4BA8-AD29-C967A8CA0CE1) that will help us for the next setup phase: integrating the SQL engine with the JavaScript MLE using PL/SQL functions, and more precisely, how JavaScript imports will be managed:
```sql
-- Installing a PL/SQL package to make Chance functions accessible in SQL
-- See how the chance_module_env MLE environment is being used so that dependencies resolution goes well
create or replace package chance as
 function address( p_doc in json ) return varchar2 as mle module chance_extended env chance_module_env signature 'chance.address';
 function address return varchar2 as mle module chance_extended env chance_module_env signature 'chance.address';
 function age return number as mle module chance_extended env chance_module_env signature 'chance.age';
 function age( p_doc in json ) return number as mle module chance_extended env chance_module_env signature 'chance.age';
 function altitude return number as mle module chance_extended env chance_module_env signature 'chance.altitude';
 function altitude( p_doc in json ) return number as mle module chance_extended env chance_module_env signature 'chance.altitude';
 function ampm( p_doc in json ) return varchar2 as mle module chance_extended env chance_module_env signature 'chance.ampm';
 function ampm return varchar2 as mle module chance_extended env chance_module_env signature 'chance.ampm';
 function android_id( p_doc in json ) return varchar2 as mle module chance_extended env chance_module_env signature 'chance.android_id';
 function android_id return varchar2 as mle module chance_extended env chance_module_env signature 'chance.android_id';
 function animal( p_doc in json ) return varchar2 as mle module chance_extended env chance_module_env signature 'chance.animal';
 function animal return varchar2 as mle module chance_extended env chance_module_env signature 'chance.animal';
 function apple_token( p_doc in json ) return varchar2 as mle module chance_extended env chance_module_env signature 'chance.apple_token';
 function apple_token return varchar2 as mle module chance_extended env chance_module_env signature 'chance.apple_token';
 function areacode return varchar2 as mle module chance_extended env chance_module_env signature 'chance.areacode';
 function areacode( p_doc in json ) return varchar2 as mle module chance_extended env chance_module_env signature 'chance.areacode';
 function avatar( p_doc in json ) return varchar2 as mle module chance_extended env chance_module_env signature 'chance.avatar';
 function avatar return varchar2 as mle module chance_extended env chance_module_env signature 'chance.avatar';
 function bb_pin return varchar2 as mle module chance_extended env chance_module_env signature 'chance.bb_pin';
 function bb_pin( p_doc in json ) return varchar2 as mle module chance_extended env chance_module_env signature 'chance.bb_pin';
 function birthday( p_doc in json ) return date as mle module chance_extended env chance_module_env signature 'chance.birthday';
 function birthday return date as mle module chance_extended env chance_module_env signature 'chance.birthday';
 function bool( p_doc in json ) return boolean as mle module chance_extended env chance_module_env signature 'chance.bool';
 function bool return boolean as mle module chance_extended env chance_module_env signature 'chance.bool';
 function cc return varchar2 as mle module chance_extended env chance_module_env signature 'chance.cc';
 function cc( p_doc in json ) return varchar2 as mle module chance_extended env chance_module_env signature 'chance.cc';
 function cc_type return varchar2 as mle module chance_extended env chance_module_env signature 'chance.cc_type';
 function cc_type( p_doc in json ) return varchar2 as mle module chance_extended env chance_module_env signature 'chance.cc_type';
 function cf( p_doc in json ) return varchar2 as mle module chance_extended env chance_module_env signature 'chance.cf';
 function cf return varchar2 as mle module chance_extended env chance_module_env signature 'chance.cf';
 function character return varchar2 as mle module chance_extended env chance_module_env signature 'chance.character';
 function character( p_doc in json ) return varchar2 as mle module chance_extended env chance_module_env signature 'chance.character';
 function city( p_doc in json ) return varchar2 as mle module chance_extended env chance_module_env signature 'chance.city';
 function city return varchar2 as mle module chance_extended env chance_module_env signature 'chance.city';
 function coin( p_doc in json ) return varchar2 as mle module chance_extended env chance_module_env signature 'chance.coin';
 function coin return varchar2 as mle module chance_extended env chance_module_env signature 'chance.coin';
 function color( p_doc in json ) return varchar2 as mle module chance_extended env chance_module_env signature 'chance.color';
 function color return varchar2 as mle module chance_extended env chance_module_env signature 'chance.color';
 function company return varchar2 as mle module chance_extended env chance_module_env signature 'chance.company';
 function company( p_doc in json ) return varchar2 as mle module chance_extended env chance_module_env signature 'chance.company';
 function country return varchar2 as mle module chance_extended env chance_module_env signature 'chance.country';
 function country( p_doc in json ) return varchar2 as mle module chance_extended env chance_module_env signature 'chance.country';
 function county return varchar2 as mle module chance_extended env chance_module_env signature 'chance.county';
 function county( p_doc in json ) return varchar2 as mle module chance_extended env chance_module_env signature 'chance.county';
 function cpf return varchar2 as mle module chance_extended env chance_module_env signature 'chance.cpf';
 function cpf( p_doc in json ) return varchar2 as mle module chance_extended env chance_module_env signature 'chance.cpf';
 function currency return json as mle module chance_extended env chance_module_env signature 'chance.currency';
 function currency( p_doc in json ) return json as mle module chance_extended env chance_module_env signature 'chance.currency';
 function currency_pair( p_doc in json ) return json as mle module chance_extended env chance_module_env signature 'chance.currency_pair';
 function currency_pair return json as mle module chance_extended env chance_module_env signature 'chance.currency_pair';
 function d10( p_doc in json ) return number as mle module chance_extended env chance_module_env signature 'chance.d10';
 function d10 return number as mle module chance_extended env chance_module_env signature 'chance.d10';
 function d100 return number as mle module chance_extended env chance_module_env signature 'chance.d100';
 function d100( p_doc in json ) return number as mle module chance_extended env chance_module_env signature 'chance.d100';
 function d12 return number as mle module chance_extended env chance_module_env signature 'chance.d12';
 function d12( p_doc in json ) return number as mle module chance_extended env chance_module_env signature 'chance.d12';
 function d20( p_doc in json ) return number as mle module chance_extended env chance_module_env signature 'chance.d20';
 function d20 return number as mle module chance_extended env chance_module_env signature 'chance.d20';
 function d30( p_doc in json ) return number as mle module chance_extended env chance_module_env signature 'chance.d30';
 function d30 return number as mle module chance_extended env chance_module_env signature 'chance.d30';
 function d4( p_doc in json ) return number as mle module chance_extended env chance_module_env signature 'chance.d4';
 function d4 return number as mle module chance_extended env chance_module_env signature 'chance.d4';
 function d6 return number as mle module chance_extended env chance_module_env signature 'chance.d6';
 function d6( p_doc in json ) return number as mle module chance_extended env chance_module_env signature 'chance.d6';
 function d8 return number as mle module chance_extended env chance_module_env signature 'chance.d8';
 function d8( p_doc in json ) return number as mle module chance_extended env chance_module_env signature 'chance.d8';
 function "date" return date as mle module chance_extended env chance_module_env signature 'chance.date';
 function "date"( p_doc in json ) return varchar2 as mle module chance_extended env chance_module_env signature 'chance.date';
 function "date"( p_doc in json, p_will_be_date in boolean ) return date as mle module chance_extended env chance_module_env signature 'chance.date';
 function depth return number as mle module chance_extended env chance_module_env signature 'chance.depth';
 function depth( p_doc in json ) return number as mle module chance_extended env chance_module_env signature 'chance.depth';
 function dollar return varchar2 as mle module chance_extended env chance_module_env signature 'chance.dollar';
 function dollar( p_doc in json ) return varchar2 as mle module chance_extended env chance_module_env signature 'chance.dollar';
 function domain( p_doc in json ) return varchar2 as mle module chance_extended env chance_module_env signature 'chance.domain';
 function domain return varchar2 as mle module chance_extended env chance_module_env signature 'chance.domain';
 function email return varchar2 as mle module chance_extended env chance_module_env signature 'chance.email';
 function email( p_doc in json ) return varchar2 as mle module chance_extended env chance_module_env signature 'chance.email';
 function euro return varchar2 as mle module chance_extended env chance_module_env signature 'chance.euro';
 function euro( p_doc in json ) return varchar2 as mle module chance_extended env chance_module_env signature 'chance.euro';
 function exp return varchar2 as mle module chance_extended env chance_module_env signature 'chance.exp';
 function exp( p_doc in json ) return varchar2 as mle module chance_extended env chance_module_env signature 'chance.exp';
 function exp_month( p_doc in json ) return varchar2 as mle module chance_extended env chance_module_env signature 'chance.exp_month';
 function exp_month return varchar2 as mle module chance_extended env chance_module_env signature 'chance.exp_month';
 function exp_year( p_doc in json ) return varchar2 as mle module chance_extended env chance_module_env signature 'chance.exp_year';
 function exp_year return varchar2 as mle module chance_extended env chance_module_env signature 'chance.exp_year';
 function falsy return varchar2 as mle module chance_extended env chance_module_env signature 'chance.falsy';
 function falsy( p_doc in json ) return varchar2 as mle module chance_extended env chance_module_env signature 'chance.falsy';
 function fbid return varchar2 as mle module chance_extended env chance_module_env signature 'chance.fbid';
 function fbid( p_doc in json ) return varchar2 as mle module chance_extended env chance_module_env signature 'chance.fbid';
 function first( p_doc in json ) return varchar2 as mle module chance_extended env chance_module_env signature 'chance.first';
 function first return varchar2 as mle module chance_extended env chance_module_env signature 'chance.first';
 function floating( p_doc in json ) return number as mle module chance_extended env chance_module_env signature 'chance.floating';
 function floating return number as mle module chance_extended env chance_module_env signature 'chance.floating';
 function gender return varchar2 as mle module chance_extended env chance_module_env signature 'chance.gender';
 function gender( p_doc in json ) return varchar2 as mle module chance_extended env chance_module_env signature 'chance.gender';
 function geohash return varchar2 as mle module chance_extended env chance_module_env signature 'chance.geohash';
 function geohash( p_doc in json ) return varchar2 as mle module chance_extended env chance_module_env signature 'chance.geohash';
 function geojson return json as mle module chance_extended env chance_module_env signature 'chance.geojson';
 function geojson( p_doc in json ) return json as mle module chance_extended env chance_module_env signature 'chance.geojson';
 function google_analytics( p_doc in json ) return varchar2 as mle module chance_extended env chance_module_env signature 'chance.google_analytics';
 function google_analytics return varchar2 as mle module chance_extended env chance_module_env signature 'chance.google_analytics';
 function guid( p_doc in json ) return varchar2 as mle module chance_extended env chance_module_env signature 'chance.guid';
 function guid return varchar2 as mle module chance_extended env chance_module_env signature 'chance.guid';
 function hammertime return number as mle module chance_extended env chance_module_env signature 'chance.hammertime';
 function hammertime( p_doc in json ) return number as mle module chance_extended env chance_module_env signature 'chance.hammertime';
 function hash return varchar2 as mle module chance_extended env chance_module_env signature 'chance.hash';
 function hash( p_doc in json ) return varchar2 as mle module chance_extended env chance_module_env signature 'chance.hash';
 function hashtag( p_doc in json ) return varchar2 as mle module chance_extended env chance_module_env signature 'chance.hashtag';
 function hashtag return varchar2 as mle module chance_extended env chance_module_env signature 'chance.hashtag';
 function hour( p_doc in json ) return number as mle module chance_extended env chance_module_env signature 'chance.hour';
 function hour return number as mle module chance_extended env chance_module_env signature 'chance.hour';
 function iban return varchar2 as mle module chance_extended env chance_module_env signature 'chance.iban';
 function iban( p_doc in json ) return varchar2 as mle module chance_extended env chance_module_env signature 'chance.iban';
 function "integer" return number as mle module chance_extended env chance_module_env signature 'chance.integer';
 function "integer"( p_doc in json ) return number as mle module chance_extended env chance_module_env signature 'chance.integer';
 function ip( p_doc in json ) return varchar2 as mle module chance_extended env chance_module_env signature 'chance.ip';
 function ip return varchar2 as mle module chance_extended env chance_module_env signature 'chance.ip';
 function ipv6( p_doc in json ) return varchar2 as mle module chance_extended env chance_module_env signature 'chance.ipv6';
 function ipv6 return varchar2 as mle module chance_extended env chance_module_env signature 'chance.ipv6';
 function klout( p_doc in json ) return number as mle module chance_extended env chance_module_env signature 'chance.klout';
 function klout return number as mle module chance_extended env chance_module_env signature 'chance.klout';
 function last return varchar2 as mle module chance_extended env chance_module_env signature 'chance.last';
 function last( p_doc in json ) return varchar2 as mle module chance_extended env chance_module_env signature 'chance.last';
 function latitude return number as mle module chance_extended env chance_module_env signature 'chance.latitude';
 function latitude( p_doc in json ) return number as mle module chance_extended env chance_module_env signature 'chance.latitude';
 function letter( p_doc in json ) return varchar2 as mle module chance_extended env chance_module_env signature 'chance.letter';
 function letter return varchar2 as mle module chance_extended env chance_module_env signature 'chance.letter';
 function locale return varchar2 as mle module chance_extended env chance_module_env signature 'chance.locale';
 function locale( p_doc in json ) return varchar2 as mle module chance_extended env chance_module_env signature 'chance.locale';
 function longitude( p_doc in json ) return number as mle module chance_extended env chance_module_env signature 'chance.longitude';
 function longitude return number as mle module chance_extended env chance_module_env signature 'chance.longitude';
 function millisecond return number as mle module chance_extended env chance_module_env signature 'chance.millisecond';
 function millisecond( p_doc in json ) return number as mle module chance_extended env chance_module_env signature 'chance.millisecond';
 function minute( p_doc in json ) return number as mle module chance_extended env chance_module_env signature 'chance.minute';
 function minute return number as mle module chance_extended env chance_module_env signature 'chance.minute';
 function month( p_doc in json ) return varchar2 as mle module chance_extended env chance_module_env signature 'chance.month';
 function month return varchar2 as mle module chance_extended env chance_module_env signature 'chance.month';
 function name return varchar2 as mle module chance_extended env chance_module_env signature 'chance.name';
 function name( p_doc in json ) return varchar2 as mle module chance_extended env chance_module_env signature 'chance.name';
 function natural( p_doc in json ) return number as mle module chance_extended env chance_module_env signature 'chance.natural';
 function natural return number as mle module chance_extended env chance_module_env signature 'chance.natural';
 function normal( p_doc in json ) return number as mle module chance_extended env chance_module_env signature 'chance.normal';
 function normal return number as mle module chance_extended env chance_module_env signature 'chance.normal';
 function paragraph( p_doc in json ) return varchar2 as mle module chance_extended env chance_module_env signature 'chance.paragraph';
 function paragraph return varchar2 as mle module chance_extended env chance_module_env signature 'chance.paragraph';
 function phone return varchar2 as mle module chance_extended env chance_module_env signature 'chance.phone';
 function phone( p_doc in json ) return varchar2 as mle module chance_extended env chance_module_env signature 'chance.phone';
 function postal return varchar2 as mle module chance_extended env chance_module_env signature 'chance.postal';
 function postal( p_doc in json ) return varchar2 as mle module chance_extended env chance_module_env signature 'chance.postal';
 function postcode return varchar2 as mle module chance_extended env chance_module_env signature 'chance.postcode';
 function postcode( p_doc in json ) return varchar2 as mle module chance_extended env chance_module_env signature 'chance.postcode';
 function prefix( p_doc in json ) return varchar2 as mle module chance_extended env chance_module_env signature 'chance.prefix';
 function prefix return varchar2 as mle module chance_extended env chance_module_env signature 'chance.prefix';
 function prime( p_doc in json ) return number as mle module chance_extended env chance_module_env signature 'chance.prime';
 function prime return number as mle module chance_extended env chance_module_env signature 'chance.prime';
 function profession return varchar2 as mle module chance_extended env chance_module_env signature 'chance.profession';
 function profession( p_doc in json ) return varchar2 as mle module chance_extended env chance_module_env signature 'chance.profession';
 function province( p_doc in json ) return varchar2 as mle module chance_extended env chance_module_env signature 'chance.province';
 function province return varchar2 as mle module chance_extended env chance_module_env signature 'chance.province';
 function radio( p_doc in json ) return varchar2 as mle module chance_extended env chance_module_env signature 'chance.radio';
 function radio return varchar2 as mle module chance_extended env chance_module_env signature 'chance.radio';
 function rpg( p_doc in varchar2 ) return json as mle module chance_extended env chance_module_env signature 'chance.rpg';
 function second( p_doc in json ) return number as mle module chance_extended env chance_module_env signature 'chance.second';
 function second return number as mle module chance_extended env chance_module_env signature 'chance.second';
 function sentence return varchar2 as mle module chance_extended env chance_module_env signature 'chance.sentence';
 function sentence( p_doc in json ) return varchar2 as mle module chance_extended env chance_module_env signature 'chance.sentence';
 function ssn return varchar2 as mle module chance_extended env chance_module_env signature 'chance.ssn';
 function ssn( p_doc in json ) return varchar2 as mle module chance_extended env chance_module_env signature 'chance.ssn';
 function state return varchar2 as mle module chance_extended env chance_module_env signature 'chance.state';
 function state( p_doc in json ) return varchar2 as mle module chance_extended env chance_module_env signature 'chance.state';
 function street( p_doc in json ) return varchar2 as mle module chance_extended env chance_module_env signature 'chance.street';
 function street return varchar2 as mle module chance_extended env chance_module_env signature 'chance.street';
 function string( p_doc in json ) return varchar2 as mle module chance_extended env chance_module_env signature 'chance.string';
 function string return varchar2 as mle module chance_extended env chance_module_env signature 'chance.string';
 function suffix return varchar2 as mle module chance_extended env chance_module_env signature 'chance.suffix';
 function suffix( p_doc in json ) return varchar2 as mle module chance_extended env chance_module_env signature 'chance.suffix';
 function syllable( p_doc in json ) return varchar2 as mle module chance_extended env chance_module_env signature 'chance.syllable';
 function syllable return varchar2 as mle module chance_extended env chance_module_env signature 'chance.syllable';
 function timestamp return number as mle module chance_extended env chance_module_env signature 'chance.timestamp';
 function timestamp( p_doc in json ) return number as mle module chance_extended env chance_module_env signature 'chance.timestamp';
 function timezone return json as mle module chance_extended env chance_module_env signature 'chance.timezone';
 function timezone( p_doc in json ) return json as mle module chance_extended env chance_module_env signature 'chance.timezone';
 function tld return varchar2 as mle module chance_extended env chance_module_env signature 'chance.tld';
 function tld( p_doc in json ) return varchar2 as mle module chance_extended env chance_module_env signature 'chance.tld';
 function tv( p_doc in json ) return varchar2 as mle module chance_extended env chance_module_env signature 'chance.tv';
 function tv return varchar2 as mle module chance_extended env chance_module_env signature 'chance.tv';
 function twitter( p_doc in json ) return varchar2 as mle module chance_extended env chance_module_env signature 'chance.twitter';
 function twitter return varchar2 as mle module chance_extended env chance_module_env signature 'chance.twitter';
 function url( p_doc in json ) return varchar2 as mle module chance_extended env chance_module_env signature 'chance.url';
 function url return varchar2 as mle module chance_extended env chance_module_env signature 'chance.url';
 function word return varchar2 as mle module chance_extended env chance_module_env signature 'chance.word';
 function word( p_doc in json ) return varchar2 as mle module chance_extended env chance_module_env signature 'chance.word';
 function wp7_anid( p_doc in json ) return varchar2 as mle module chance_extended env chance_module_env signature 'chance.wp7_anid';
 function wp7_anid return varchar2 as mle module chance_extended env chance_module_env signature 'chance.wp7_anid';
 function wp8_anid2( p_doc in json ) return varchar2 as mle module chance_extended env chance_module_env signature 'chance.wp8_anid2';
 function wp8_anid2 return varchar2 as mle module chance_extended env chance_module_env signature 'chance.wp8_anid2';
 function year( p_doc in json ) return number as mle module chance_extended env chance_module_env signature 'chance.year';
 function year return number as mle module chance_extended env chance_module_env signature 'chance.year';
 function zip( p_doc in json ) return varchar2 as mle module chance_extended env chance_module_env signature 'chance.zip';
 function zip return varchar2 as mle module chance_extended env chance_module_env signature 'chance.zip';
 function zodiac( p_doc in json ) return varchar2 as mle module chance_extended env chance_module_env signature 'chance.zodiac';
 function zodiac return varchar2 as mle module chance_extended env chance_module_env signature 'chance.zodiac';
 function template( p_doc in json ) return json as mle module chance_extended env chance_module_env signature 'template';
end;
/
```

That's all!

You can now use all the new functions to generate random data. See the following examples.

## Using Chance.js functions in SQL

Our first example will focus on very basic data generation:

```sql
-- Generate a random string
select chance.string;

STRING
______________
^2nZ*5n*Xhv
```

```sql
-- Generate a random string with 5 chars
select chance.string( json { 'length': 5 } );

CHANCE.STRING(JSON{'LENGTH':5})    
__________________________________
@AgM3
```

If you want more than 1 row, you can leverage this trick:

```sql
-- Generate 7 random strings with 10 chars
select chance.string( json { 'length': 10 } ) connect by level <= 7;

CHANCE.STRING(JSON{'LENGTH':10})
___________________________________
#^lgZ*6r!i
N7alrlEznY
g(2@6A3c4o
NB9M4WXsMk
^uI*jJG1oM
T6bBsYKfFd
bMv]69L]WQ
```

```sql
-- Generate 5 prime numbers (between 0 to 10000)
select chance.prime connect by level <= 5;
   
   PRIME
________
    5591
    2113
    9239
    9479
     587
```

```sql
-- Generate a random credit card number (Mastercard)
select chance.cc( json { 'type': 'Mastercard' } );
   
CHANCE.CC(JSON{'TYPE':'MASTERCARD'})
_______________________________________
5199094555584914
```

```sql
-- Generate 2 random dates (which includes time for Oracle database)
-- first one is a DATE, second one is a formatted string (or varchar2)
select chance."date", to_char( chance."date", 'yyyy-mm-dd hh24:mi:ss' );
   
date        TO_CHAR(CHANCE."DATE",'YYYY-MM-DDHH24:MI:SS')
___________ ________________________________________________
15/09/49    2039-01-29 09:33:45
```
Remark that `DATE` is an Oracle datatype and thus you need to use lowercase call to distinguish it from the function, that's why the double-quotes are mandatory and the lower case must be used here (as for "`integer`"). In the previous example, the first date is 15th of September 2049 because of my localized session (France).

```sql
-- Generate a random date as a string (or varchar2)
-- here, the format is the one from Chance: american (28th of January 2024, MM/DD/YYYY)
select chance."date"( json{ 'string': true } );

CHANCE."DATE"(JSON{'STRING':TRUE})
_____________________________________
1/28/2024
```

```sql
-- Generate a random date as a string (or varchar2), but this time with format DD/MM/YYYY
select chance."date"( json{ 'string': true, 'american': false } );

CHANCE."DATE"(JSON{'STRING':TRUE,'AMERICAN':FALSE})
______________________________________________________
15/2/2103
```

```sql
-- Generate a random date with a fixed year
select chance."date"( json{ 'year': 2023 } );

ORA-04156: Unable to convert MLE value to database CHAR value. Reason:
unsupported type for value:2023-03-08T02:45:14.246Z.
```

Here you can see some limitations or flexibility (depending on your point of view) of interoperability between JavaScript and PL/SQL. When passing a JSON parameter, we can ask for an extended generation mode for a given data generator. But the PL/SQL function signatures have to be compatible because PL/SQL is strongly typed. Hence the trick here is to have a third signature for that case:

```js
function "date" return date as mle module chance_extended env chance_module_env signature 'chance.date';
 function "date"( p_doc in json ) return varchar2 as mle module chance_extended env chance_module_env signature 'chance.date';
 -- This one will help:
 function "date"( p_doc in json, p_will_be_date in boolean ) return date as mle module chance_extended env chance_module_env signature 'chance.date'; 
```

If we add a second parameter then we allow the resulting type to be an Oracle database `DATE` instead of a `VARCHAR2`:

```sql
-- Generate a random date with a fixed year
-- Passing true as the second argument (p_will_be_date) so that 
-- the returned JavaScript date is properly casted into a DATE
select chance."date"( json{ 'year': 2023 }, true );

CHANCE."DATE"(JSON{'YEAR':2023},TRUE)
________________________________________
21/02/23
```

```sql
-- Generate a random address
select chance.address;

ADDRESS
_________________
66 Bomcu Drive
```

```sql
-- Generate a random timezone
select chance.timezone;

TIMEZONE
__________________________________________________________________________________________________________________________
{"name":"Samoa Standard Time","abbr":"SST","offset":13,"isdst":false,"text":"(UTC+13:00) Samoa","utc":["Pacific/Apia"]}
```

You can see how it is now easy to generate random data, it's up to you... but one last word!

## Using extended Chance.js functions in SQL
If you've taken a look at the extended MLE module above, you may have seen some additional code. In fact, while looking for JavaScript data generators, I found out that [Fony.js](https://github.com/captainsafia/fony) ([MIT License](https://en.wikipedia.org/wiki/MIT_License)) from [Safia Abdalla](https://github.com/captainsafia) provided an interesting concept of `JSON template`. So I've decided to integrate it and improve it to benefit from the additional possibilities offered by `Chance.js` in terms of generator customization using a JSON document as a parameter. The result is that the `template()` function can now be used to generate random JSON documents based on JSON templates!

Let's see some examples:

```sql
-- Generate a JSON document containing tags as an array of 3 words
select chance.template( json {'tags': ['word', 3]} );

CHANCE.TEMPLATE(JSON{'TAGS':['WORD',3]})    
___________________________________________
{"tags":["ehugu","luf","fiksojuh"]}
```

```sql
-- Generate a JSON document containing random information for a person
select chance.template( json { 'name': 'name', 'age': 'age', 'address': 'address' } );

CHANCE.TEMPLATE(JSON{'NAME':'NAME','AGE':'AGE','ADDRESS':'ADDRESS'})
_______________________________________________________________________
{"address":"1904 Luwe Ridge","age":38,"name":"Cory Hopkins"}
```
You'll note that the ordering of the JSON fields is not respected. This is expected since the `template()` function leverages the `Object.keys()` function which in the latest ES standard doesn't guarantee the ordering anymore. But that's not really a problem, right?

```sql
-- Generate 2 random JSON documents for fictious races
-- We display the JSON document formatted for better readability
select json_serialize( chance.template( json {'raceId': { '$natural': {'min': 1, 'max': 99999} }, 
                                              'name': 'name', 
                                              'laps': { '$natural': {'min': 5, 'max': 42} }, 
                                              'date': 'date', 
                                              'podium': {} } ) pretty ) as new_races 
  connect by level <= 2;

NEW_RACES
__________________________________________
{
  "date" : "2056-11-14T13:26:53.751000Z",
  "laps" : 35,
  "name" : "Scott Wilkins",
  "podium" :
  {
  },
  "raceId" : 64315
}
{
  "date" : "2060-10-11T13:18:00.826000Z",
  "laps" : 5,
  "name" : "Wesley Ramsey",
  "podium" :
  {
  },
  "raceId" : 84434
}
```

This would bring some interesting ability to populate the [JSON Relational Duality Views](https://docs.oracle.com/en/database/oracle/oracle-database/23/jsnvu/loe.html) examples from the 23c FREE documentation.

## Conclusion
We've seen how to import an ES Module inside the Oracle database 23c FREE Developer Release thanks to the JavaScript MultiLingual Engine. We've also seen how dependencies resolution work using an MLE environment.

As you can see, the possibilities are infinite and benefiting from such a data generator for both simple values but also JSON documents is incredibly useful. This could be used for [Oracle Application Express](https://apex.oracle.com/en/) (APEX) applications, demos, random data for unit testing, etc.

And now, it's up to you!

## Resources to continue learning
As Jeff Smith said in his [blog post on MLE JS Modules & Snippets](https://www.thatjeffsmith.com/archive/2023/04/oracle-23c-free-developer-release-mle-js-modules-snippets/), we _highly_ recommend reading the [23c JavaScript Developer Guide (Docs.)](https://docs.oracle.com/en/database/oracle/oracle-database/23/mlejs/).

You may want also to review Martin Bach's [blog post on Using JavaScript community modules in Oracle Database 23c Free - Developer Release](https://blogs.oracle.com/developers/post/using-javascript-community-modules-in-oracle-database-23c-free-developer-release) which I've stolen some of the commands used here.

Don't forget to provide us your feedback on the [23c FREE community forum](https://forums.oracle.com/ords/apexds/domain/dev-community/category/oracle-database-free) that we monitor and where you can provide feedback.

## Thanks
I would never have discovered the possibilities highlighted here without the help of Martin Bach and Lucas Victor Braun-Lohrer, respectively Product Manager for JavaScript MLE and Program Manager at Oracle Labs; so thanks a lot!!!