Database type generator for Kysely - Supports PostgreSQL, MySQL, SQLite, and MSSQL
npm install kysely-genGenerate TypeScript types from your database for Kysely.
Supports PostgreSQL, MySQL, SQLite, and MSSQL.
``shPostgreSQL
npm install kysely-gen kysely pg
Usage
sh
PostgreSQL (auto-detected from URL)
DATABASE_URL=postgres://user:pass@localhost:5432/db npx kysely-genMySQL (auto-detected from URL)
DATABASE_URL=mysql://user:pass@localhost:3306/db npx kysely-genSQLite (auto-detected from file extension)
npx kysely-gen --url ./database.dbMSSQL (auto-detected from URL or connection string)
npx kysely-gen --url "mssql://user:pass@localhost:1433/db"
npx kysely-gen --url "Server=localhost;Database=db;User Id=user;Password=pass"Explicit dialect
npx kysely-gen --dialect mysql --url mysql://user:pass@localhost:3306/db
`Options
| Option | Description |
|--------|-------------|
|
| Database dialect: postgres, mysql, sqlite, or mssql (auto-detected) |
| --out | Output file (default: ./db.d.ts) |
| --schema | Schema to introspect (repeatable) |
| --url | Database URL (overrides DATABASE_URL) |
| --camel-case | Convert names to camelCase |
| --include-pattern | Only include matching tables |
| --exclude-pattern | Exclude matching tables |
| --zod | Generate Zod schemas instead of TypeScript interfaces |
| --no-boolean-coerce | Output 0 \| 1 instead of coercing to boolean for CHECK constraints |Zod Schema Generation
Generate Zod validation schemas with inferred types instead of TypeScript interfaces. Requires Zod v4+:
`sh
npm install zod@4
npx kysely-gen --zod
`This generates
with Zod schemas and inferred types:`typescript
import { z } from 'zod';export const userSchema = z.object({
id: z.number(),
email: z.string(),
name: z.string().nullable(),
createdAt: z.date(),
});
export const newUserSchema = z.object({
id: z.number().optional(),
email: z.string(),
name: z.string().nullable().optional(),
createdAt: z.union([z.date(), z.string()]).optional(),
});
export const userUpdateSchema = z.object({
id: z.number().optional(),
email: z.string().optional(),
name: z.string().nullable().optional(),
createdAt: z.union([z.date(), z.string()]).optional(),
});
export type User = z.infer;
export type NewUser = z.infer;
export type UserUpdate = z.infer;
`Three schemas are generated per table:
- Select schema (
): What you get from queries
- Insert schema (newUserSchema): For inserts - auto-increment/default columns are optional
- Update schema (userUpdateSchema): For updates - all columns are optionalThe
--zod flag replaces TypeScript interface generation. Types are inferred from schemas via z.infer<>, ensuring they never drift.Example
`sh
kysely-gen --out ./src/db.d.ts --camel-case
`Generates:
typescript
import type { ColumnType } from 'kysely';export type Generated = T extends ColumnType
? ColumnType
: ColumnType;
export type Status = 'pending' | 'approved' | 'rejected';
export interface User {
id: Generated;
email: string;
status: Status;
createdAt: ColumnType;
}
export interface DB {
users: User;
}
`Features
$3
- Enums mapped to union types
- for select/insert/update type differences
- Generated for auto-increment and default columns
- Materialized views, domains, partitioned tables
- Array columns$3
- Enums parsed from column definitions
- ColumnType for timestamps, bigint, decimal
- Generated for auto_increment columns
- Views
- Geometry types (Point, LineString, Polygon)
- tinyint(1) mapped to boolean$3
- Generated for INTEGER PRIMARY KEY (auto-increment)
- Views
- JSON columns mapped to JsonValue
- Simple type affinity mapping (no ColumnType wrappers)$3
- for identity and computed columns
- Views
- Multi-schema support (default: dbo)
- All MSSQL types: uniqueidentifier, datetime2, datetimeoffset, money, xml, varbinary, etc.
- Both URL (mssql://) and ADO.NET connection string formats$3
SQLite and MSSQL store booleans as integers (0/1). When a
CHECK(col IN (0, 1)) constraint is detected, kysely-gen generates:TypeScript:
boolean
Zod: Use
to output raw 0 | 1 instead:`sh
kysely-gen --zod --no-boolean-coerce
`Type Mappings
Types are generated to match the default behavior of each database driver. If you customize your driver's type parsers, the generated types may not match.
$3
Generated types match
(pg) defaults:- Dates (
timestamp, date): Driver returns Date objects. Inserts accept Date | string.
- Bigint (int8): Driver returns string (JS Number can't represent full int8 range). Inserts accept string | number | bigint.
- Numeric (numeric, decimal): Driver returns string for precision. Inserts accept string | number.| PostgreSQL | TypeScript |
|------------|------------|
|
int2, int4, integer | number |
| int8, bigint | ColumnType |
| numeric, decimal | ColumnType |
| timestamp, date | ColumnType |
| jsonb, json | JsonValue |
| text[], int4[] | string[], number[] |$3
Generated types match
mysql2 defaults:- Dates (
datetime, timestamp): Driver returns Date objects. Inserts accept Date | string.
- Bigint: Driver returns string. Inserts accept string | number | bigint.
- Decimal: Driver returns string for precision. Inserts accept string | number.| MySQL | TypeScript |
|-------|------------|
|
tinyint(1) | boolean |
| int, smallint | number |
| bigint | ColumnType |
| decimal | ColumnType |
| datetime, timestamp | ColumnType |
| json | JsonValue |
| point | Point |
| enum('a','b') | 'a' \| 'b' |$3
Generated types match
better-sqlite3 defaults. SQLite has simpler type affinity - no ColumnType wrappers needed since values are returned as-is.| SQLite | TypeScript |
|--------|------------|
|
INTEGER, INT, BIGINT | number |
| REAL, DOUBLE, FLOAT | number |
| TEXT, VARCHAR, CHAR | string |
| BLOB | Buffer |
| DATE, DATETIME, TIMESTAMP | string |
| JSON | JsonValue |
| BOOLEAN | number (0/1) |$3
Generated types match
tedious defaults. The driver handles type conversions, so simple types are used without ColumnType wrappers.| MSSQL | TypeScript |
|-------|------------|
|
int, smallint, tinyint, bigint | number |
| decimal, numeric, money, smallmoney | number |
| float, real | number |
| datetime, datetime2, date, time | Date |
| datetimeoffset, smalldatetime | Date |
| char, varchar, nchar, nvarchar | string |
| text, ntext | string |
| uniqueidentifier | string |
| xml | string |
| bit | boolean |
| binary, varbinary, image | Buffer |
| sql_variant | unknown` |MIT