Squell

Introduction

Squell is a type-safe wrapper for the Sequelize library, usable in TypeScript 2.1+ projects. Squell takes the Sequelize type definitions a step further by allowing models to be designed using ModelSafe. Each model is defined as a class with all of its properties being decorated with the relevant ModelSafe data types, which will be in turned mapped to Sequelize types.

Additionally to serializing ModelSafe models to SQL databases, Squell provides what is essentially a type-safe query language that compiles down to Sequelize queries. This means that any queries on the database are partially checked at compile time, which obviously can't capture all errors, but stops small issues like type inconsistencies and typos.

Installation

npm install --save squell

Usage

Model definitions (including associations/relationships) are written using the ModelSafe library. See the ModelSafe documentation for more information on how to define models.

An example model definition for a basic user in our application might look like:

@modelsafe.model('user')
class User extends modelsafe.Model {
  @modelsafe.attr(modelsafe.STRING)
  public username: string;
 
  @modelsafe.attr(modelsafe.STRING)
  public email: string;
}

Squell also provides its own @model, @attr and @assoc decorators that are companion pieces to the ModelSafe decorators. These can be used to provide specific Sequelize options, such as attribute options like autoIncrement which is not captured in ModelSafe. Take a look at the documentation for more information.

To query that model, you might do something like this:

let db = new squell.Database('mysql://username:password@localhost/db');
 
db.query(User)
  .where(m => m.email.eq('[e-mail]').or(m.id.lt(5)))
  .find()
  .then((users: User[]) => {
    // Do something with `users`.
  });

This query would find a user with the email of exactly [e-mail], or an ID larger than 5, but with the benefit of the query being checked at compile time. Take a look at the API documentation for more information on the query operators available - but for the most part they are the same as the Sequelize operators.

Documentatation

The API documentation generated using TypeDoc is available online.

To generate API documentation from the code into the docs directory, run:

npm run docs

Testing

First install the library dependencies and the SQLite3 library:

npm install
npm install sqlite3

To execute the test suite using SQLite as the backend, run:

npm run test

By default, the tests will not log the SQL queries performed to keep the output sane. If a test is giving particular trouble, run the tests with LOG_TEST_SQL turned on to inspect the generated SQL queries:

LOG_TEST_SQL=1 npm run test

License

This project is licensed under the MIT license. Please see LICENSE.md for more details.

Limitations

• Any static functions or methods on the model classes are not yet transferred over to Sequelize. This means when trying to call them they will be undefined.
• Calling update will do both an update and findAll call instead of just the single update call. This is because relationships have to be automatically assigned by Squell, which requires the updated instance model.
• Associations will always be updated every create/update call, even if the association hasn't changed. These associations will only be updated if an include for that association model has be set, however.
• bulkCreate cannot create objects with relationships.