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

``typescript
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

$3

`
npm install -g schemats
`

$3

`
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.

$3

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
`

$3

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:

`json
{
"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.

$3

We can import osm.ts directly

`typescript

// 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
= 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.

`bash
schemats generate -c postgres://postgres@localhost/db -n yournamespace -o db.ts
`

and import them with
`typescript
import {yournamespace} from './db'
`

It is now encouraged to generate without namespace
`bash
schemats generate -c postgres://postgres@localhost/db -o db.ts
`
and import them with
`typescript
import * as yournamespace from './db'
// or
import {table_a, table_b} from './db'
``

As TypeScript's documentation describes,
having a top level namespace is needless. This was discussed in #25.

Generating schema typescript files with namespace still works in v1.0, but it is discouraged and subjected to
removal in the future.

#### Support Strict Null-Checking

Version 1.0 supports
strict null-checking
and reflects the _NOT NULL_ constraint defined in PostgreSQL schema.