Schemats

Upstream fork of https://github.com/SweetIQ/schemats, with new features / options:

• forInsert: defines any nullable / columns with defaults optional ?:, default false
• forInsertNull: use with forInsert, makes any null columns required, default false
• customTypes: define a mapping of custom types, e.g. for emulating enum behavior
• customHeader: allows adding a custom string header to the generated document
• prettierConfig: specify a path to prettier to auto-format the output
• tableNamespaces: whether to add extra namespaces for columns, default false

yarn install @tgriesser/schemats

Using Schemats, you can generate TypeScript interface definitions from (Postgres, MySQL) SQL database schema automatically.

Start with a database schema:

Automatically have the following TypesScript Interface generated

interface Users {
    id: number
    username: string
    password: string
    last_logon: Date
}

For an overview on the motivation and rational behind this project, please take a look at Statically typed PostgreSQL queries in Typescript .

Quick Start

Installing Schemats

npm install -g schemats

Generating the type definition from schema

schemats generate -c postgres://postgres@localhost/osm -t users -o osm.ts
schemats generate -c mysql://mysql@localhost/osm -t users -o osm.ts

The above commands will generate typescript interfaces for osm database with table users. The resulting file is stored as osm.ts.

Generating the type definition for all the tables in a postgres schema

To generate all type definitions for all the tables within the schema 'public':

Note: MySQL does not have a default public schema, but should it have a schema named public, this will still work.

schemats generate -c postgres://postgres@localhost/osm -s public -o osm.ts
schemats generate -c mysql://mysql@localhost/osm -s public -o osm.ts

If neither the table parameter nor the schema parameter is provided, all tables in schema 'public' will be generated, so the command above is equivalent to:

schemats generate -c postgres://postgres@localhost/osm -o osm.ts
schemats generate -c mysql://mysql@localhost/osm -o osm.ts

Using schemats.json config file

Schemats supports reading configuration from a json config file (defaults to schemats.json). Instead of passing configuration via commandline parameter like done above, it is also possible to supply the configuration through a config file. The config file supports the same parameters as the commandline arguments.

For example, if a schemats.json exists in the current working directory with the following content:

{
    "conn": "postgres://postgres@localhost/osm",
    "table": ["users"]
}

Running schemats generate here is equivalent to running schemats generate -c postgres://postgres@localhost/osm -t users -o osm.ts.

Writing code with typed schema

We can import osm.ts directly

// imports the _osm_ namespace from ./osm.ts

import * as osm from './osm'

// Now query with pg-promise and have a completely typed return value

let usersCreatedAfter2013: Array<osm.users> = await db.query(
    "SELECT * FROM users WHERE creation_time >= '2013-01-01'"
)

// We can decide to only get selected fields

let emailOfUsersCreatedAfter2013: Array<{
    email: osm.users['email']
    creation_time: osm.users['creation_time']
}> = await db.query(
    "SELECT (email, creation_time) FROM users WHERE creation_time >= '2013-01-01'"
)

With generated type definition for our database schema, we can write code with autocompletion and static type checks.

Using schemats as a library

Schemats exposes two high-level functions for generating typescript definition from a database schema. They can be used by a build tool such as grunt and gulp.