knex-schema-inspector

Utility for extracting information about existing DB schema

This library currently supports Postgres, MySQL, MS SQL, SQLite, and OracleDB. We aim to have support for the same databases as the main knex project.

Installation

Install the package through NPM or Yarn:

npm install knex-schema-inspector

yarn add knex-schema-inspector

Usage

The package is initialized by passing it an instance of Knex:

1import Knex from 'knex';
2import schemaInspector from 'knex-schema-inspector';
3
4const database = Knex({
5  client: 'mysql',
6  connection: {
7    host: '127.0.0.1',
8    user: 'your_database_user',
9    password: 'your_database_password',
10    database: 'myapp_test',
11    charset: 'utf8',
12  },
13});
14
15const inspector = schemaInspector(database);
16
17export default inspector;

Examples

1import inspector from './inspector';
2
3async function logTables() {
4  const tables = await inspector.tables();
5  console.log(tables);
6}

API

Note: MySQL doesn't support the schema parameter, as schema and database are ambiguous in MySQL.

Note 2: Some database types might return slightly more information than others. See the type files for a specific overview what to expect from driver to driver.

Note 3: MSSQL doesn't support comment for either tables or columns

Methods

Table

• tables(): Promise<string[]>
• tableInfo(table?: string): Promise<Table | Table[]>
• hasTable(table: string): Promise<boolean>

Columns

• columns(table?: string): Promise<{ table: string, column: string }[]>
• columnInfo(table?: string, column?: string): Promise<Column[] | Column>
• primary(table: string): Promise<string>

Foreign Keys

• foreignKeys(): Promise<ForeignKey>

Misc.

• withSchema(schema: string): void

Tables

tables(): Promise<string[]>

Retrieve all tables in the current database.

1await inspector.tables();
2// => ['articles', 'images', 'reviews']

tableInfo(table?: string): Promise<Table | Table[]>

Retrieve the table info for the given table, or all tables if no table is specified

1await inspector.tableInfo('articles');
2// => {
3//   name: 'articles',
4//   schema: 'project',
5//   comment: 'Informational blog posts'
6// }
7
8await inspector.tableInfo();
9// => [
10//   {
11//     name: 'articles',
12//     schema: 'project',
13//     comment: 'Informational blog posts'
14//   },
15//   { ... },
16//   { ... }
17// ]

hasTable(table: string): Promise<boolean>

Check if a table exists in the current database.

1await inspector.hasTable('articles');
2// => true

Columns

columns(table?: string): Promise<{ table: string, column: string }[]>

Retrieve all columns in a given table, or all columns if no table is specified

1await inspector.columns();
2// => [
3//   {
4//     "table": "articles",
5//     "column": "id"
6//   },
7//   {
8//     "table": "articles",
9//     "column": "title"
10//   },
11//   {
12//     "table": "images",
13//     "column": "id"
14//   }
15// ]
16
17await inspector.columns('articles');
18// => [
19//   {
20//     "table": "articles",
21//     "column": "id"
22//   },
23//   {
24//     "table": "articles",
25//     "column": "title"
26//   }
27// ]

columnInfo(table?: string, column?: string): Promise<Column[] | Column>

Retrieve all columns from a given table. Returns all columns if table parameter is undefined.

1await inspector.columnInfo('articles');
2// => [
3//   {
4//     name: "id",
5//     table: "articles",
6//     data_type: "VARCHAR",
7//     default_value: null,
8//     max_length: null,
9//     numeric_precision: null,
10//     numeric_scale: null,
11//     is_nullable: false,
12//     is_unique: false,
13//     is_primary_key: true,
14//     has_auto_increment: true,
15//     foreign_key_column: null,
16//     foreign_key_table: null,
17//     comment: "Primary key for the articles collection"
18//   },
19//   { ... },
20//   { ... }
21// ]
22
23await inspector.columnInfo('articles', 'id');
24// => {
25//    name: "id",
26//    table: "articles",
27//    data_type: "VARCHAR",
28//    default_value: null,
29//    max_length: null,
30//    numeric_precision: null,
31//    numeric_scale: null,
32//    is_nullable: false,
33//    is_unique: false,
34//    is_primary_key: true,
35//    has_auto_increment: true,
36//    foreign_key_column: null,
37//    foreign_key_table: null,
38//    comment: "Primary key for the articles collection"
39//  }

primary(table: string): Promise<string>

Retrieve the primary key column for a given table

1await inspector.primary('articles');
2// => "id"

Foreign Keys

Retrieve all configured foreign key constraints.

1await inspector.foreignKeys();
2// => [
3//   {
4//     table: 'directus_files',
5//     column: 'folder',
6//     foreign_key_table: 'directus_folders',
7//     foreign_key_column: 'id',
8//     constraint_name: 'directus_files_folder_foreign',
9//     on_update: 'CASCADE',
10//     on_delete: 'SET NULL'
11//   },
12//   {
13//     table: 'directus_files',
14//     column: 'modified_by',
15//     foreign_key_table: 'directus_users',
16//     foreign_key_column: 'id',
17//     constraint_name: 'directus_files_modified_by_foreign',
18//     on_update: 'CASCADE',
19//     on_delete: 'SET NULL'
20//   }
21// ]

Misc.

withSchema(schema: string): void

Not supported in MySQL

Set the schema to use. Note: this is set on the inspector instance and only has to be done once:

1inspector.withSchema('my-schema');

Contributing

Pull requests are welcome. For major changes, please open an issue first to discuss what you would like to change.

Please make sure to update tests as appropriate.

Tests

First start docker containers:

1$ docker-compose up -d

Then run tests:

1$ npm test

Standard mocha filter (grep) can be used:

1$ npm test -- -g '.tableInfo'

License

MIT