kanel-kysely/README.md

Kysely extension for Kanel

# Kysely extension for Kanel

Generate [Kysely](https://kysely.dev/) types directly from your Postgres database.
This packages extends [Kanel](https://github.com/kristiandupont/kanel) with some Kysely specific features.
Check ./example/.kanelrc.js for how to customize your schema generation.

```typescript
// @generated
// This file is automatically generated by Kanel. Do not modify manually.

import type { ColumnType, Selectable, Insertable, Updateable } from "kysely";

/** Identifier type for actor */
export type ActorId = number & { __flavor?: "ActorId" };

/** Represents the table public.actor */
export default interface ActorTable {
  /** Database type: pg_catalog.int4 */
  actor_id: ColumnType<ActorId, ActorId | null, ActorId | null>;

  /** Database type: pg_catalog.varchar */
  first_name: ColumnType<string, string, string | null>;

  /** Database type: pg_catalog.varchar */
  last_name: ColumnType<string, string, string | null>;

  /** Database type: pg_catalog.timestamp */
  last_update: ColumnType<Date, Date | null, Date | null>;
}

export type Actor = Selectable<ActorTable>;

export type NewActor = Insertable<ActorTable>;

export type ActorUpdate = Updateable<ActorTable>;
```

Assuming you already have Kanel installed, add this with

```bash
$ npm i -D kanel-kysely
```

To use it, add it to your `.kanelrc.js` file:

```javascript
const { makeKyselyHook } = require("kanel-kysely");

module.exports = {
  // ... your config here.

  preRenderHooks: [makeKyselyHook()],
};
```

## Note About Branded IDs

Kanel generates some types with extra guards.

```typescript
/** Identifier type for actor */
export type ActorId = number & { __flavor?: "ActorId" };
```

`{ __flavor?: 'ActorId' }` exists at build time and _not at runtime_. It will prevent you from accidentally passing an incorrect value for the Id.

To pass a string value as primary key or foreign key reference, just add a type assertion for the `<table>Id` generated type.

In cases such as subqueries, the type assertion will happen automatically.

## Usage with `CamelCasePlugin`

If you use Kysely with `CamelCasePlugin` then append `kyselyCamelCaseHook` to `preRenderHooks`:

```ts
const { makeKyselyHook, kyselyCamelCaseHook } = require("kanel-kysely");

module.exports = {
  // ... your config here.

  preRenderHooks: [makeKyselyHook(), kyselyCamelCaseHook],
};
```

## Type Filter

If you're using Kysely for migrations, you might want to filter the types of the migration tables, such as `kysely_migration` and `kysely_migration_lock`. The `kyselyTypeFilter` will do this for you. 

```ts
  const { kyselyTypeFilter } = require("kanel-kysely");

  module.exports = {
    /// ... your config here.

    typeFilter: kyselyTypeFilter,
  };
```