knex-stringcase

knex-stringcase

Easily convert database column names for use in your Node.js application when using knex.

By default, this library assumes your database uses snake_case and your Node.js application uses camelCase. However, these settings can be changed.

🚀 Why Knex Stringcase?

If your database columns follow a snake_case convention (a common practice), you might want to convert them into a more JavaScript-friendly camelCase for use in your application.

For example, you might have database columns id, is_verified, deleted_at, but your application prefers id, isVerified, deletedAt. This library takes care of that conversion.

Example usage:

const user = await db('users')
    .first('id', 'isVerified')
    .where({ id: params.userId, deletedAt: null });

This will return an object:

{
  "id": "xxxx",
  "isVerified": true
}

This is maps database field is_verified to isVerified and allows you to refer to deleted_at using deletedAt. No more snake_case to camelCase troubles!

🔧 How It Works

By leveraging knex’s built-in configuration options: wrapIdentifier and postProcessResponse. You can use these configuration options yourself, this library just makes the conversions simpler.

🌟 Features

• Full TypeScript support as of version 1.5.0.
• Automatic conversion between snake_case and camelCase or custom formats.
• Extend and modify conversion logic with custom functions.
• Handles nested objects and subqueries.

📦 Installation

Use npm (or yarn, pnpm, etc.):

npm i knex-stringcase

📘 Usage

Add knex-stringcase to your knex configuration.

import knex from 'knex';
import knexStringcase from 'knex-stringcase';

const db = knex({
  client: 'mysql',
  connection: {
    host: '127.0.0.1',
    user: 'your_database_user',
    password: 'your_database_password',
    database: 'myapp_test'
  },
  ...knexStringcase(),
});

This library overwrites wrapIdentifier and postProcessResponse pass them as library options instead, they will be run when keys are in database format. If you wish to run when keys are in application format use appWrapIdentifier and appPostProcessResponse.

📰 Library Options

stringcase

Default: 'snakecase'

Define how keys are modified when heading to the database. Accepts a string found in stringcase (e.g. 'snakecase'), or a custom function.

This parameter may be an array describing more than one alteration in sequence.

stringcase: ['snakecase', (value) => 'db_' + value]
// 'myKey' => 'db_my_key'

appStringcase

Default: 'camelcase'

Define how keys are converted when returning to the application. This attribute may also be be an array and operates closely to how stringcase operates above.

wrapIdentifier

In order to use this knex feature with the library ensure that you pass it as a parameter.

Knex documentation

appWrapIdentifier

(value: string, queryContext?: unknown) => string

Custom function to modify identifiers before conversion. Runs when keys are still in application format, on the way to the database.

postProcessResponse

In order to use this knex feature with the library ensure that you pass it as a parameter.

Knex documentation

appPostProcessResponse

(result: unknown, queryContext?: unknown) => unknown

Custom function to process the response after conversion. Runs when keys are in application format, after the data is retrieved from the database.

recursiveStringcase

(value: object, path: string, queryContext?: unknown) => boolean

A function to control nested object conversions (useful for subqueries or JSON fields). The function receives the object and its path in dot notation. Return true to convert the object.

🔄 Upgrade Guide (1.5.0 → 1.5.5)

1.5.5: knexStringcase() no longer has to wrap your entire knex configuration instead you can insert it into the options.

1.5.0: TypeScript support is available out-of-the-box.

🤝 Contributing

Contributions are welcome! Feel free to open an issue or submit a pull request. Note that we avoid dependencies whenever possible.