@jaysalvat/smart-model NPM

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SmartModel

SmartModel is a fun experiment over ES6 Javascript Proxy.

It tends to bring useful tools and best practices to Javascript data objects.

Small footprint <2Kb gzipped
Value transformation
Value formatting
Value type validation
Value content validation
Default value
Readonly properties
Computed properties
Exceptions (or not) if invalid
Nested models
Hooks
Subscriptions

Compatibility

Should works on modern browsers. Check if tests pass on your browser.

SmartModel uses javascript proxy. It unfortunately makes it incompatible with VueJs reactive properties.

Install

Provided formats are IFFE, ESM, CJS and UMD, all minified.

NPM

npm install @jaysalvat/smart-model

import SmartModel from '@jaysalvat/smart-model'

Module from CDN

import SmartModel from 'https://unpkg.com/@jaysalvat/smart-model@latest/build/smart-model.esm.min.js'

The old way

<script src="https://unpkg.com/@jaysalvat/smart-model@latest/build/smart-model.min.js"></script>

Usage

function readingTime(text) { /*...*/ }

const Post = SmartModel.create('Post', {
  title: {
    required: true,
    type: String
  },
  body: {
    required: true,
    type: String,
    rule: {
      tooShort: (value) => value.length < 100,
      tooLong: (value) => value.length > 1000
    }
  },
  createdAt: {
    type: Date,
    default: new Date(),
    transform: (value) => new Date(value),
    format: (value) => value.toLocaleString()
  },
  updatedAt: {
    type: Date,
    default: new Date(),
    transform: (value) => new Date(value),
    format: (value) => value.toLocaleString()
  },
  // Nested model
  author: {
    required: true,
    type: {
      firstname: {
        required: true,
        type: String
      },
      lastname: {
        required: true,
        type: String,
        transform: (value) => value.toUpperCase()
      },
      fullname: (author) => author.firstname + ' ' + author.lastname
    }
  },
  // Computed properties
  bodyLength: (post) => post.body.length,
  readingTime: (post) => readingTime(post.body)
},
// Settings
{
  strict: true,
  exceptions: true,
  methods: {
    $onUpdate() {
      this.updatedAt = new Date()
    }
  }
})

const post = new Post({
  title: 'My new post',
  body: 'Very long post...',
  author: {
    firstname: 'James',
    lastname: 'Hetfield'
  }
})

Try a console.log(post)

Post {
  createdAt: 2020-01-31T09:50:00.000Z,
  updatedAt: 2020-01-31T09:50:00.000Z,
  title: 'My new post',
  body: 'Very long post...',
  author: Author {  
    firstname: 'James', 
    lastname: 'Hetfield' 
  }
}

Let's try to log some other magic properties

console.log(post.author.fullname)
console.log(post.createdAt)
console.log(post.readingTime)

They return

James HETFIELD
01/31/2020, 9:50:00 AM
12 minutes

Documentation

Schema

Options for property:

Option	Type	Description
default	any	Default value if the property is undefined
format	fn	Function to format the value when its read
readonly	bool	Boolean to prevent a value to be overwritten
required	bool	Boolean to prevent a value to be empty
rule	object	Object which contains the validation rules
transform	fn	Function to transform the value when its written
type	any	Required type of a value

default

The default value if the property is undefined.

format

A function to format the value when its read.

const Event = SmartModel.create('Event', {
  name: { 
    type: String 
  },
  date: {
    type Date,
    format: (value) => new Date(value).toLocaleString()
  }
})

Use with caution, it could cause unexpected effects when the model is cloned.

const clonedObject = Object.assign({}, model)

The formatted value becomes the new value of the cloned object. Consider using the $get() method instead.

const clonedObject = model.$get()

Or consider using a computed property.

const Event = SmartModel.create('Event', {
  name: { 
    type: String 
  },
  date: {
    type Date,
  },
  formattedDate: (value) => new Date(value).toLocaleString()
})

readonly

The value can't be overwritten after init.

required

The value is required. See settings.empty for the empty value check function.

rule

An object which contains the validation rules Multiple rules of validation can be set on a property.

const Discount = SmartModel.create('Discount', {
  percent: {
    type: Number,
    rule: {
      'min': {value) => value < 0,
      'max': {value) => value > 100
    }
  }
})

An exception is throw with the rule code when the condition if true.

transform

Function to transform the value when its written.

const Event = SmartModel.create('Event', {
  name: { 
    type: String 
  },
  date: {
    type Date,
    transform: (value) => new Date(value)
  }
})

type

The required type of a value. Type can be Array, Boolean, Date, Function, Object, String or a class. If a schema is set as a type, a nested model will be created.

const Post = SmartModel.create('Post', {
  title: { 
    type: String 
  },
  body: { 
    type: String 
  },
  Date: { 
    type: Date 
  },
  author: {
    type {
      firstname: {
        type: String
      },
      lastname: {
        type: String
      }
    }
  }
})

An existing model can be set as a type in order to nest this model.

const Author = SmartModel.create('Author', {
  firstname: {
    type: String
  },
  lastname: {
    type: String
  }
})

const Post = SmartModel.create('Post', {
  title: { 
    type: String 
  },
  body: { 
    type: String 
  },
  Date: { 
    type: Date 
  },
  body: { 
    type: string 
  },
  author: {
    type: Author
  }
})

An array of models can be attach to a property with this fancy syntax.

const Article = SmartModel.create('Article', {
  body: { 
    type: String 
  },
  comments: {
    type: [ Comment ]
  }
})

The syntax above is a shortcut for:

const Article = SmartModel.create('Article', {
  body: { 
    type: String 
  },
  comments: {
    type: Array,
    transform: (value) => Comment.$hydrate(value)
  }
})

Now comments always is an array of Comment models.

Settings

Option	Type	Default	Description
empty	fn	fn	Function to check if a value is empty if required
exceptions	bool/object	object	Object of exceptions settings
methods	object	object	Object of custom methods
strict	bool	false	Boolean to set only properties defined in the schema

empty

The function to check if a value is empty or not. Default function is the function below.

(value) => value === '' || value === null || value === undefined

strict

If strictset to true, only properties defined in the schema will be set.

exceptions

Any type of thrown exceptions can be set individually. By default the exceptions settings is an object these default values:

Option	Type	Default
readonly	bool	false
required	bool	true
rule	bool	true
strict	bool	false
type	bool	true

If exceptions is set to true, all types of exceptions will be thrown. If exceptions is set to false, all types of exceptions will be thrown.

methods

Custom methods can be added to model. Those methods will be accessible in any instances of the model.

const Article = SmartModel.create('Article', {
  body: {
    type: String
  }
}, {
  methods: {
    excerpt(limit = 10) {
      return this.body.substr(0, limit) + '…'
    }
  }
})

Methods

$get

Returns standard JSON from the model content.

const article = new Article()

const json = article.$get()

$post / $put

Replaces the model properties. Existing properties are deleted. An exception is thrown if the properties are required.

const article = new Article()

article.$put({
  title: 'My article'
})

$patch

Same as $post / $put, but only passed properties are updated.

$delete

Delete a or muliple properties of the model. An exception is thrown if the properties are required.

const article = new Article()

article.$delete([ 'title', 'body' ])

$subscribe

Adds an update listener. It will be called any time a value is updated.

article.$subscribe((property, value) => {
  console.log(property, 'has been updated with', value)
})

To unsubscribe the change listener, invoke the function returned by subscribe.

const unsubscribe = article.$subscribe((property, value) => {
  console.log(property, 'has been updated with', value)
})

unsubscribe()

Static methods

$check

Returns an array of potential errors if a payload was passed to the model.

const errors = Article.$check(payload)

$hydrate

Turns an object or an array of objects into models. Useful with API responses.

fetch('https://api.com/post')
  .then(response => response.json())
  .then(response => Post.$hydrate(response))
  .then(response) => { /* Array of hydrated Post models */ }

fetch('https://api.com/post/1234')
  .then(response => response.json())
  .then(response => Post.$hydrate(response))
  .then(response) => { /* Hydrated Post model */ }

Hooks

Hooks are triggered before and after properties are set, get, updated or deleted.

const User = SmartModel.create('User', {
  username: {
    type: String
  }
}, {
  methods: {
    $onBeforeDelete() {}
    $onBeforeGet() {}
    $onBeforeSet() {}
    $onBeforeUpdate() {}
    $onDelete() {}
    $onGet() {}
    $onSet() {}
    $onUpdate() {}
  }
})