Gostek

Gostek is a completely typesafe querybuilder written in TypeScript

Fancy, huh?

Goals of the project

Typesafe queries

One of the main design goals of this library is to be able to provide completely typesafe queries. It means that when you do SELECT id, name you actually get { id: number, age: string } without the need to write any types manually 😎

Generating types based on DB structure

What makes this library unique is the fact that you don't have to write any types or models manually. They're all generated based on your database structure and provide 100% typesafety!

Examples (draft syntax)

Gostek generates types and models based on your DB schema, for example:

const User = {
  name: 'user',
  columns: {
    id: { type: 'int4', notNull: true },
    name: { type: 'text', notNull: false },
  },
} as const;

Immutable query

Each function returns an immutable query representation:

const query1 = db.from(User).select(['id']);

The following query selects age and id from User:

const query2 = db.from(User).select(['id', 'age']);

It would be a compile-time error to try to select columns which don't exist:

const query3 = db.from(User).select(['id', 'foo']);
// Argument of type '"foo"' is not assignable to parameter of type '"*" | ("age" | "id")[]'.

All queries are typesafe! Executing it returns only fields which are selected:

const result1 = await db.from(User).select(['id']).execute();
// {
//   readonly id: number;
// }[]

Mind that nullability of name was taken into account as well.

There's a shorthand notation for selecting all properties and it's also typesafe:

const result2 = await db.from(User).select('*').execute();
// {
//   readonly id: number;
//   readonly name: string | null;
// }[]

Typesafe operators

Operators are also typesafe! In this case, Gostek knows that types of User.name and name have to match:

db.from(User).select(['name']).where(['name', Op.$eq, 'Kasia']);

The library is also aware of the operator you're using:

db.from(User)
  .select(['name'])
  .where(['id', Op.$in, [1, 2, 3]]);
// $in requires an array!

This would be a compile-time TypeScript error:

db.from(User).select(['name']).where(['name', Op.$eq, 123]);
// Type 'number' is not assignable to type 'string | null'.

This is also an error because $in requires the argument to be an array of values:

db.from(User).select(['name']).where(['name', Op.$in, 'Michał']);
// Type 'string' is not assignable to type '(string | null)[]'.

0.1.0 plan

• finish generator which outputs safely-typed models for simple tables
• support PostgreSQL
• make sure all queries from the README work on a real database

0.2.0 plan

• allow for more complex where conditions (and, or)