json-sequelize

Translate JSON Schemas to Sequelize model definitions.

Install

npm i --save json-sequelize

Use

Simply provide a valid JSON schema to the sequelizer function.

const { sequelizer } = require('json-sequelize')

const schema = {
  title: 'User Schema',
  unique: ['username', 'email'],
  required: ['username', 'email', 'password'],
  properties: {
    id: { type: 'integer' },
    active: { type: 'boolean' },
    username: { type: 'string', maxLength: 255 },
    password: { type: 'string' },
    email: { type: 'string', format: 'email' },
    role: { type: 'string', enum: ['admin', 'staff', 'guest'], default: 'guest' },
    tags: { type: 'array', items: { type: 'string' } },
    createdAt: { type: 'string', format: 'date-time' }
  }
}

const model = sequelizer(schema)

console.log(model)

Yields:

{
  id: { type: Sequelize.INTEGER },
  active: { type: Sequelize.BOOLEAN },
  username: { type: Sequelize.STRING, unique: true, allowNull: false },
  password: { type: Sequelize.TEXT, allowNull: false },
  email: { type: Sequelize.TEXT, unique: true, allowNull: false },
  role: { type: Sequelize.ENUM('admin', 'staff', 'guest'), defaultValue: 'guest' },
  tags: { type: Sequelize.JSONB },
  createdAt: { type: Sequelize.DATE, defaultValue: Sequelize.NOW }
}

Mixins

You can provide one or more Mixins to the sequelizer function, each with a selector and a handler.

Mixin handler

The handler must be a Function that returns a new Sequelize model definition or SKIP if ignoring selected properties.

The handler function gets called with an object containing:

• schema - the schema object
• key - the current property key
• property - the current property object
• definition - the current model definition
• SKIP - Symbol required to exclude a property
• Sequelize - the Sequelize object

Using handler to ignore props

Sometimes it can be useful to include computed properties in the JSON Schema but to exclude them in the Sequelize model definitions.

const schema {
  computed: ['beep', 'boop'],
  properties: {
    id: {},
    beep: {},
    boop: {}
  }
}

const mixin = {
  handler: ({ key, schema, SKIP }) => schema.computed.includes(key) && SKIP
}

The resulting model will only include the id property:

{
  id: {}
}

Using handler to modify props

Typically, the handler is used to update one or more properties with Sequelize definitions.

const schema = {
  properties: {
    id: { type: 'integer' }
  }
}

const mixin = {
  selector: 'id',
  handler: ({ Sequelize }) => ({
    type: Sequelize.STRING,
    defaultValue: () => nanoid(),
    primaryKey: true
  })
}

const model = sequelizer(schema, mixin)

The resulting model:

{
  id: { type: Sequelize.STRING, primaryKey: true, defaultValue: [Function Anonymous] }
}

The above model definition will be replicated in each of the following examples:

Mixin selector

The selector can be a String, Object, or Function:

Mixin selector (String)

The simplest way is providing the property key as a String:

const mixin = {
  selector: 'id',
  handler: () => ({/*  */})
}

Mixin selector (Object)

Another way is to provide a matching key:value pair to match one or more of the schema.properties:

const mixin = {
  selector: { type: 'integer' },
  handler: ({ Sequelize }) => ({/*  */})
}

Using the key property, allows targeting by schema.properties keys. This approach is equivalent to providing the value as a plain String.

const mixin = {
  selector: { key: 'id' },
  handler: () => ({/*  */})
}

Mixin selector (Function)

A function will execute against each property in schema.properties and should return a truthy value.

const mixin = {
  selector: ({ key }) => key === 'id',
  handler: () => ({/*  */})
}

The selector function gets called with an object containing:

• schema - the schema object
• key - the property key
• property - the property object

Multiple Mixins

Combining mixins is done by adding them to an array, where each mixin will run consecutively.

const model = sequelizer(schema, [mixin1, mixin2, ...mixins])

Tests

Run npm test to run tests.

Run npm coverage to produce a test coverage report.

Credits

Originally forked from ronalddddd/sequelizer - upgraded to a purely functional style with some added sugar.

License

MIT © Goran Spasojevic