Sequelize Transformations

Sequelize plugin to add configurable attribute transformations. It allows you to define transformation functions to run on attribute values when an instance is updated (through assignment, set, build, create etc.). The transformation functions can be enabled and configured on attribute level.

Installation

npm install sequelize-transformations

Activation

To activate the plugin for all your models, call the plugin on your sequelize instance before you define your models:

var sequelizeTransformations = require('sequelize-transformations');

sequelizeTransformations(sequelize);

// Now you can define your models

Usage

To use transformations for an attribute, just add them to its definition:

var Model = sequelize.define('Model', {
  email: {
    type: Sequelize.DataTypes.STRING,
    lowercase: true,
    trim: true
  }
});

With this configuration, the email attribute will always be trimmed and transformed to lower case.

Predefined Transformations

The plugin comes with the following predefined transformations:

• trim: trim value
• lowercase: transform value to all lower case
• uppercase: transform value to all upper case

Custom Transformations

It is possible to override predefined transformations or add your own by passing an object as the second argument:

sequelizeTransformations(sequelize, {
  trim: function(val, defintion) {
    return val.toString().replace(/ /g, '*');
  },
  append: function(val, definition) {
    return val.toString() + definition['append'];
  },
  removeMilliseconds: function(val, definition) {
    if(val) {
      val.setMilliseconds(0);
    }

    return val;
  }
});

This would override the trim transform and add a new one called append. Every transformation function is called with two parameters: the value to transform and the definition of the attribute being transformed.

Notes

• If more than one transformation is defined on an attribute, then the order in which they are executed is unpredictable. This is generally not an issue as you should not use mutually exclusive transformation together, e.g. lowercase and uppercase.
• If an attribute is updated with the raw option set to true, then the transformation will not be run.

TypeScript

Activation

import {sequelizeTransformations, ModelAttributeDefinition} from 'sequelize-transformations';

type TransformationOptions = {
  removeMilliseconds?: boolean;
}

sequelizeTransformations(sequelize, {
  removeMilliseconds: function(date: Date, definition: ModelAttributeDefinition<TransformationOptions>) {
    if(definition.removeMilliseconds) {
      date?.setMilliseconds(0);
    }

    return date;
  }
});

Usage

import {DataTypes, Optional} from 'sequelize';
import {ModelAttributesWithTransformations} from 'sequelize-transformations';

interface ModelAttributes {
  id: number;
  email: string;
}

interface ModelCreationAttributes extends Optional<ModelAttributes, 'id'> {}

var Model = sequelize.define('Model', (<ModelAttributesWithTransformations<ModelCreationAttributes>>{
  email: {
    type: DataTypes.STRING,
    lowercase: true,
    trim: true
  }
}));