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An ORM for SQLite and NodeJS. Flyweight combines a very simple API for performing basic operations, with the ability to create SQL queries that are parsed by the ORM.

For example, if you create a query in ./database/sql/users/roles.sql that looks like this:

    groupArray( as roles
    users u join
    userRoles ur on ur.userId = join
    roles r on ur.roleId =
where = $name
group by

A function db.users.roles will be available in the API with the correct types.

auto-completed code

Shorthand JSON functions

object(,, as user

is just shorthand for

    'social', as user

Other commands available are groupArray which is shorthand for json_group_array, and array, which is shorthand for json_array.

Alias stars

Normally, SQLite doesn't support aliased stars, but this syntax is now available when writing SQL statements with Flyweight.

    e.*, as locationName
    events e join
    locations l on e.locationId =

Creating tables

Tables are created the same way as they are in SQL. The native types available in strict mode are integer, real, text, blob, and any. In addition to these types, four additional types are included by default: boolean, date, and json. boolean is a column in which the values are restricted to 1 or 0, date is a JavaScript Date stored as an ISO8601 string, and json is json stored as text. These additional types are automatically parsed by the ORM.

create table events (
    id integer primary key,
    name text not null,
    startTime date not null,
    locationId integer references locations

Each table has a singular and plural form. If you want to get one row with the basic API, you can use:

const event = await db.event.get({ id: 100 });

If you want to get many rows, you can use:

const names = await{ id: eventIds }, 'name');

If you want to insert a row, you can do:

const id = await{
  name: 'Eugene Bareman',
  city: 'Auckland'

Getting started

mkdir test
cd test
npm init
npx create-flyweight database

You can run the npx command at the root of either an existing or a new project. Once that is done, you can import the database this way:

import { db } from './database/db.js';

await db.user.insert({ name: 'Andrew' });
const users = await db.users.get();

A users table has already been created for you to play around with.

You can update types whenever you change the SQL by either calling npm run watch to automatically update the types, or npm run types to do it manually.


Tables are defined in ./database/sql/tables.sql. You can add or change tables from here and then run the migration command npm run migrate <migration-name>.

If you want to reset the migration system to a new database that already has tables created on it, edit the tables.sql file and then run npm run reset.

If you want to add a new column to a table without needing to drop the table, make sure you put the column at the end of the list of columns.

Default values

Default values can be set for boolean and date columns using the following syntax:

create table users (
  id integer primary key,
  isDisabled boolean not null default false,
  createdAt date not null default now()

current_timestamp will not work properly when wanting to set the default date to the current time. This is because current_timestamp does not include timezone information and therefore when parsing the date string from the database, JavaScript will assume it is in local time when it is in fact in UTC time.


Every table has get, update, insert, and remove methods available to it, along with any of the custom methods that are created when you add a new SQL file to the corresponding table's folder. Views only have the get method available to them.


insert simply takes one argument - params, with the keys and values corresponding to the column names and values you want to insert. It returns the primary key, or part of the primary key if the table has a composite primary key. The plural version of insert is for batch inserts and takes an array of params. It doesn't return anything.


update takes two arguments - the query (or null), and the params you want to update. It returns a number representing the number of rows that were affected by the query. For example:

await{ id: 100 }, { city: 'Brisbane' });

which corresponds to

update coaches set city = 'Brisbane' where id = 100;


get takes two optional arguments. The first is params - an object representing the where clause. For example:

const fights = await db.fights.get({ cardId: 9, titleFight: true });

translates to

select * from fights where cardId = 9 and titleFight = 1;

The keys to params must be the column names of the table. The values can either be of the same type as the column, an array of values that are the same type as the column or null. If an array is passed in, an in clause is used, such as:

const fights = await db.fights.get({ cardId: [1, 2, 3] });

which translates to

select * from fights where cardId in (1, 2, 3);

If null is passed in as the value, the SQL will use is null.

All of the arguments are passed in as parameters for security reasons.

The second argument to get can be one of three possible values:

  1. a string representing a column to select. In this case, the result returned is a single value or array of single values, depending on whether a plural or singular table name is used in the query.
  2. an array of strings, representing the columns to select.
  3. An object with one or more of the following properties:

select or exclude: select can be a string or array representing the columns to select. exclude can be an array of columns to exclude, with all of the other columns being selected.

orderBy: a string representing the column to order the result by, or an array of columns to order the result by.

desc: set to true when using orderBy if you want the results in descending order.

limit and offset: corresponding to the SQL keywords with the same name.

distinct: adds the distinct keywords to the start of the select clause.

For example:

const fighters = await db.fighters.get({ isActive: true }, {
  select: ['name', 'hometown'],
  orderBy: 'reachCm',
  limit: 10

While the default interpretation of the query parameters is =, you can modify the meaning by importing not, gt, gte, lt, lte, like, match and glob.

For example:

import { not } from 'flyweightjs';

const excluded = [1, 2, 3];
const users = await db.users.get({ id: not(excluded) });

Exists and Count

These functions take one argument representing the where clause.

const count = await db.fighters.count({ hometown: 'Brisbane, Australia' });
const exists = await db.fighter.exists({ name: 'Israel Adesanya' });


remove takes one argument representing the where clause and returns the number of rows affected by the query.

const changes = await db.fighters.remove({ id: 100 });

Creating SQL queries

When the basic API doesn't do what you need it to do, you can create SQL queries. You can do this by creating a folder that is the plural version of the table name, such as ./database/sql/users. You can then put SQL files in this folder that will be available in the API in both singular and plural form, depending on whether you want a single item returned, or an array of items returned.

When creating SQL queries, make sure you give an alias to any columns in the select statement that don't have a name. For example, do not do:

select max(startTime) from events;

as there is no name given to max(startTime).

Parameters in SQL files should use the $name notation. If you want to include dynamic content that cannot be parameterized, you should use the ${column} format and then pass in a second argument when calling the SQL statement in JavaScript. For example:

select * from users where location = $location order by ${column};
const options = {
  unsafe: {
    column: 'lastName'
const users = await db.users.from({ location: 'Brisbane' }, options);

If the unsafe parameter is undefined in the options argument, it will be removed from the SQL statement.

Single quotes in strings should be escaped with \. JSON functions are automatically typed and parsed. For example, the following:

select id, object(name, startTime) as nest from events;

will have the type:

interface EventQuery {
  id: number;
  nest: { name: string, startTime: Date }

Nulls are automatically removed from all groupArray results. When all of the properties of object are from a left or right join, and there are no matches from that table, instead of returning, for example:

{ name: null, startTime: null }

the entire object will be null.

Transactions and concurrency

Transactions involve taking a connection from a pool of connections by calling getTransaction. Once you have finished using the transaction, you should call release to return the connection to the pool. If there are a large number of simultaneous transactions, the connection pool will be empty and getTransaction will start to wait until a connection is returned to the pool.

import { db } from './db.js';
import { like } from 'flyweightjs';

try {
  const tx = await db.getTransaction();
  await tx.begin();

  const coachId = await{
    name: 'Eugene Bareman',
    city: 'Auckland'
  const fighterId = await tx.fighter.get({ name: like('Israel%') }, 'id');
  await tx.fighterCoach.insert({
  await tx.commit();
catch (e) {
  await tx.rollback();
finally {


Views are treated like read-only tables. They have a get method available to them that works the same as with tables. If you want to create a view called activeUsers you can add a file in the views folder called ./database/views/activeUsers.sql that might have SQL like this:

create view activeUsers as
select * from users where isActive = true;

You can now use it in the API like this:

import { db } from './database/db.js';

const user = await db.activeUser.get({ id: 100 }, ['name', 'email']);

Cloudflare D1

Flyweight provides first-class support for D1. The only difference between the D1 API and the SQLite API is that D1 doesn't support transactions. Instead, there is a batch method available that can be used like this:

import Database from './database/db';
import files from './database/files';

export default {
  async fetch(request: Request, env: Env, ctx: ExecutionContext): Promise<Response> {
    const db = Database({
      db: env.DB,

    const projectId = 1;
    const [project, tags, issues] = await db.batch((bx) => [
      bx.project.get({ id: projectId }),
      bx.tags.get({ projectId }),
      bx.issues.get({ projectId })

    return Response.json({

To get started, run this command in the root of your Cloudflare Workers project.

npx create-flyweight d1 src/database

If your database already has tables created on it, go into src/database/sql/tables.sql and add all of the create statements and then run:

npm run reset

to reset the migration system to the current state of the database. All migration commands work on the local version of the database and interface with the wrangler migration system so that you can run apply on the remote database yourself to add any migrations.

If you have more than one database and want to create a migration for a specific database, you can run:

npm run migrate dbName migrationName

You should run npm run watch to keep the src/database/files.js updated with any new sql files or table changes while you write the code.

Running tests

To run the tests, first go into the test folder and run node setup.js to move the test database to the right location. You can then run the tests with node test.js or npm test.


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