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RawModel.js

Strongly-typed JavaScript object with support for validation and error handling.

This is a lightweight open source package for the server and browser (using module bundler) written with TypeScript. It's actively maintained, well tested and already used in production environments. The source code is available on GitHub where you can also find our issue tracker.

Related Projects

• vue-rawmodel: RawModel.js plugin for Vue.js v2. Form validation has never been easier!

Introduction

RawModel provides a mechanism for creating strongly-typed data objects with built-in logic for unified data validation and error handling. It has a simple and intuitive API and tends to be a powerful, magic-free, minimalistic and unopinionated framework for writing application data layers where you have a full control. It could be a perfect fit when writing an Express.js action, GraphQL resolver or similar and it's easily extendable.

It provides two core classes:

• Model represents strongly-typed data object with properties.
• Field represents model's property.

Both classes can be used independently but most likely you will use only the Model class.

We will be using TypeScript for code examples for the rest of the docs. If you haven't picked it up, you should!

Installation

Run the command below to install the package.

npm install --save rawmodel

This package uses promises thus you need to use Promise polyfill when promises are not supported.

Example

The code below shows a basic usage example.

import { Model } from 'rawmodel';
 
// defining a basic model
class User extends Model {
  public name: string;
 
  public constructor(data = {}) {
    super(data);
    this.defineField('name');
    this.populate(data);
  }
}
 
// usage example
const model = new User({
  'name': 'John Smith'
});
model.name; // => 'John Smith'

Examples are available inside the ./example folder. You should also check the links below:

• RawModel & ExpressJS: Using RawModel in ExpressJS actions to validate input data and handling data-related errors.

Usage

Below we explain some of the most important features that this package provides. You should check the API section to see a complete list of features.

Defining Fields

Model fields are defined using the defineField method. The code below is an example of a basic model class with a name field of type Any.

import { Model } from 'rawmodel';
 
class User extends Model {
  public name: string; // typescript property definition for field `name`
 
  public constructor(data = {}) {
    super(data);
    this.defineField('name'); // definition of the `name` field
  }
}
 
const user = new User();
user.name = 'John Smith';
user.name; // -> "John Smith"

Type Casting

Each field has a built-in system for type casting, thus we can force a value to be automatically converted to a specific type when setting a value.

this.defineField('name', {
  type: 'String', // automatically cast value to `String`
});

Common types are supported by default. A Model also represents a type. You can define your own types using the defineType method. Please see the API section for a list of all supported types and further details.

Nested Models

As mentioned above, a model also represents a type object. This way you can create complex nested structures by nesting models as shown in the example below.

import { Model } from 'rawmodel';
 
class Book extends Model {
  public title: string;
 
  public constructor(data = {}) {
    super(data);
    this.defineField('title');
  }
}
 
class User extends Model {
  public book: Book;
 
  public constructor(data = {}) {
    super(data);
    this.defineField('book', {
      type: Book,
    });
  }
}

Field Default Value

We can set a defaultValue for each field which will automatically populate a field on creation.

The defaultValue can also be a method which returns a dynamic value. This function shares the context of a field instance thus you have access to all the features of the Field class.

this.defineField('name', {
  defaultValue () { return this.value },
});

Field Fake Value

Similar to default values, we can set a fakeValue for each field, to populate a field with fake data when calling the fake() method.

The fakeValue can also be a method which returns a dynamic value. This function shares the context of a field instance, thus you have access to all the features of the Field class.

this.defineField('name', {
  fakeValue () { return this.value },
});

Field Null Value

By default, all defined fields are set to null. Similar to default and fake value we can set a nullValue option for each field, to automatically replace null values.

The nullValue can also be a method which returns a dynamic value. Note that this function shares the context of a field instance, thus you have access to all the features of the Field class.

this.defineField('name', {
  nullValue () { return '' }, // replace `null` value
});

Field Value Transformation

A field can have a custom getter and a custom setter. These methods all share the context of a field instance, thus you have access to all the features of the Field class.

this.defineField('name', {
  get (value) { return value },
  set (value) { return value },
});

Value Assignments

Model's fields are like properties of a Javascript Object. We can easily assign a value to a field through its setter method (e.g. model.name = 'value';). Instead of assigning fields one by one, we can use the populate() method as shown below.

this.populate({
  'name': 'John Smith',
  'age': 35,
});

We can allow only selected fields to be populated by using population strategies (e.g. when populating received form data).

class User extends Model {
  public id: string;
  public name: string;
 
  public constructor(data = {}) {
    super(data);
    this.defineField('id', {
      populatable: ['internal'], // list population strategy names
    });
    this.defineField('name', {
      populatable: ['input', 'internal'], // list population strategy names
    });
  }
}
 
const data = {
  'id': 100,
  'name': 'John Smith'
};
const user = new User();
user.populate(data); // -> { "id": 100, "name": "John Smith" }
user.populate(data, 'internal'); // -> { "id": 100, "name": "John Smith" }
user.serialize(data, 'input'); // -> { id: null, "name": "John Smith" }

Serialization & Filtering

Model provides useful methods for object serialization and filtering (check the API for more methods).

const user = new User({
  'name': 'John Smith', // initial value
});
 
user.scroll(function (field) { // argument is an instance of a field
  // do something useful
}).then((count) => { // number of processed fields
  user.serialize(); // -> { "name": "John Smith" }
});

Fields are serializable by default and are thus included in the result object returned by the serialize() method. We can customize the output and include or exclude fields for different occasions by using serialization strategies.

class User extends Model {
  public id: string;
  public name: string;
 
  public constructor(data = {}) {
    super(data);
    this.defineField('id', {
      serializable: ['output'], // list serialization strategy names
    });
    this.defineField('name', {
      serializable: ['input', 'output'], // list serialization strategy names
    });
    this.populate(data);
  }
}
 
const user = new User({
  'id': 100,
  'name': 'John Smith',
});
user.serialize(); // -> { "id": 100, "name": "John Smith" }
user.serialize('input'); // -> { "name": "John Smith" }
user.serialize('output'); // -> { "id": 100, "name": "John Smith" }

Commits & Rollbacks

RawModel tracks changes for all fields and provides a mechanism for committing values and rollbacks.

The example below explains how to setup and use these features.

class User extends Model {
  public name: string;
 
  public constructor(data = {}) {
    super(data);
    this.defineField('name');
  }
}
 
const user = new User();
user.name = 'Mandy Taylor'; // changing field's value
user.isChanged(); // -> true
user.commit(); // set `initialValue` of each field to the value of  `value`
user.isChanged(); // -> false
user.name = 'Tina Fey'; // changing field's value
user.rollback(); // -> reset `value` of each field to its `initialValue` (last committed value)

Validation

RawModel provides a simple mechanism for validating fields.

class User extends Model {
  public name: string;
 
  public constructor(data = {}) {
    super(data);
 
    this.defineField('name', {
      validate: [ // field validation setup
        { // validator recipe
          validator: 'presence', // [required] validator name
          message: '%{it} must be present', // [optional] error message
          code: 422, // [optional] error code
          condition () { return true }, // [optional] condition which switches the validation on/off
          it: 'it', // [optional] custom variable for the `message`
        },
      ],
    });
  }
}
 
const user = new User();
user.validate().catch((err) => {
  user.collectErrors(); // -> [{path: ['name'], errors: [{validator: 'presence', message: 'is must be present', code: 422}]}]
});

It already includes some useful built-in validators but it's super simple to define your own validator. Note that each validator function shares the context of a field instance thus you have access to all the features of the Field class.

class User extends Model {
  public name: string;
 
  constructor(data = {}) {
    super(data);
 
    this.defineValidator('coolness', function (v) {
      return v === 'cool';
    });
 
    this.defineField('name', {
      validate: [
        {
          validator: 'coolness',
          message: 'must be cool',
        },
      ],
    });
  }
}

Error Handling

RawModel provides a mechanism for handling field-related errors. The logic is aligned with validation thus validation and error handling can easily be managed in a unified way. This is great because we always deal with validation errors and can thus directly send these errors back to a user in a unified format.

class User extends Model {
  public name: string;
 
  public constructor(data = {}) {
    super(data);
 
    this.defineField('name', {
      handle: [ // field error handling setup
        { // handler recipe
          handler: 'block', // [required] handler name
          message: '%{is} unknown', // [optional] error message
          code: 422, // [optional] error code
          block (error) { return true }, // [optional] handler-specific function
          condition () { return true }, // [optional] condition which switches the handling on/off
          is: 'is', // [optional] custom variable for the `message`
        },
      ],
    });
  }
}
 
const error = new Error();
lconstet user = new User();
user.handle(error).then(() => {
  user.collectErrors(); // -> [{ path: ['name'], errors: [{ handler: 'block', message: 'is unknown', code: 422 }] }]
});

This mechanism is especially handful when saving data to a database. MongoDB could, for example, throw a uniqueness error (E11000) if we try to insert a value that already exists in the database. We can catch that error by using the handle() and then return a unified validation error message to a user.

RawModel already includes some useful built-in handlers but it's super simple to define your own handler. Note that each handler function shares the context of a field instance thus you have access to all the features of the Field class.

class User extends Model {
  public name: string;
 
  public constructor(data = {}) {
    super(data);
 
    this.defineHandler('coolness', function (e) {
      return e.message === 'cool';
    });
 
    this.defineField('name', {
      handle: [ // field error handling setup
        { // handler recipe
          handler: 'coolness', // handler name
          message: 'cool', // error message
        },
      ],
    });
  }
}

GraphQL

RawModel.js can be a perfect framework for writing GraphQL resolvers. An instance of a root model, in our case the App class, can represent GraphQL's rootValue.

import { Model } from 'rawmodel';
import { graphql, buildSchema } from 'graphql';
 
class App extends Model { // root resolver
  public hello() { // `hello` field resolver
    return 'Hello World!';
  }
}
 
const schema = buildSchema(`
  type Query {
    hello: String
  }
`);
 
const root = new App(); // root resolver
 
graphql(schema, '{ hello }', root).then((response) => {
  console.log(response);
});

API

Model Class

Model({ parent, ...data })

Abstract class which represents a strongly-typed JavaScript object.

class User extends Model {
  public name: string;
 
  public constructor({ parent, ...data } = {}) {
    super({ parent }); // initializing the Model
 
    this.defineField('name', {
      type: 'String', // [optional] field type casting
      populatable: ['input', 'internal'], // [optional] population strategies
      serializable: ['input', 'output'], // [optional] serialization strategies
      enumerable: true, // [optional] when set to `false` the field is not enumerable (ignored by `Object.keys()`)
      get (v) { return v }, // [optional] custom getter
      set (v) { return v }, // [optional] custom setter
      validate: [ // [optional] value validator recipes
        { // validator recipe (check validatable.js for more)
          validator: 'presence', // [required] validator name
          condition () { return true }, // [optional] condition which switches the validation on/off
          message: '%{it} must be present', // [optional] error message
          code: 422, // [optional] error code
          it: 'it' // [optional] custom variable for the `message`
        }
      ],
      handle: [ // [optional] error handling recipies
        { // handler recipe
          handler: 'block', // [optional] handler name
          condition () { return true }, // [optional] condition which switches the handling on/off
          message: '%{is} unknown', // [optional] error message
          code: 422, // [optional] error code
          block (error) { return true }, // [optional] handler-specific function
          is: 'is' // [optional] custom variable for the `message`
        }
      ],
      defaultValue: 'Noname', // [optional] field default value (value or function)
      fakeValue: 'Noname', // [optional] field fake value (value or function)
    });
 
    this.populate(data); // [optional] a good practice to enable data population from model constructor
    this.commit(); // [optional] a good practice to commit default data
  }
}

Model.prototype.applyErrors(errors): Model

Deeply populates fields with the provided errors.

model.applyErrors([
  {
    path: ['books', 1, 'title'], // field path
    errors: [
      {
        validator: 'presence', // or handler: ''
        message: 'is required',
        code: 422,
      },
    ],
  },
]);

Model.prototype.clear(): Model

Sets all model fields to null.

Model.prototype.clone(): Model

Returns a new Model instance which is the exact copy of the original.

Model.prototype.collect(handler): Array

Scrolls through model fields and collects results.

Model.prototype.collectErrors(): Array

Returns a list of errors for all the fields ({path, errors}[]).

model.collectErrors(); // => { path: ['name'], errors: [{ validator: 'absence', message: 'must be blank', code: 422 }] }

Model.prototype.commit(): Model

Sets initial value of each model field to the current value of a field. This is how field change tracking is restarted.

Model.prototype.defineField(name, { type, populatable, serializable, enumerable, get, set, defaultValue, fakeValue, validate }): Void

Defines a new model property.

Model.prototype.defineType(name, converter): Void

Defines a custom data type.

Model.prototype.defineValidator(name, handler): Void

Defines a custom validator.

Model.prototype.equals(value): Boolean

Returns true when the provided value represents an object with the same fields as the model itself.

Model.prototype.failFast(fail): Void

Configures validator to stop field validation on the first error.

Model.prototype.fake(): Model

Sets each model field to its fake value if the fake value generator is defined.

Model.prototype.filter(handler): Object

Converts a model into serialized data object with only the keys that pass the test.

Model.prototype.flatten(): Array

Converts the model into an array of fields.

user.flatten(); // -> [{path: [...], field: ...}, ...]

Model.prototype.getField(...keys): Field

Returns a class instance of a field at path.

Model.prototype.handle(error, { quiet }): Promise(Model)

Tries to handle the error against each field handlers and populates the model with possible errors.

try {
  // throws an error (e.g. you can call the `validate()` method)
}
catch (e) {
  model.handle(e);
}

Model.prototype.hasErrors(): Boolean

Returns true when no errors exist (inverse of isValid()). Make sure that you call the validate() method first.

Model.prototype.hasField(...keys): Boolean

Returns true when a field path exists.

Model.prototype.isChanged(): Boolean

Returns true if at least one model field has been changed.

Model.prototype.isNested(): Boolean

Returns true if nested fields exist.

Model.prototype.isValid(): Boolean

Returns true when all model fields are valid (inverse of hasErrors()). Make sure that you call the validate() method first.

Model.prototype.invalidate(): Model

Clears errors on all fields.

Model.prototype.options: Object

Model options.

Model.prototype.parent: Model

Parent model instance.

Model.prototype.populate(data, strategy): Model

Applies data to a model.

Model.prototype.reset(): Model

Sets each model field to its default value.

Model.prototype.rollback(): Model

Sets each model field to its initial value (last committed value). This is how you can discharge model changes.

Model.prototype.root: Model

The first model instance in a tree of models.

Model.prototype.scroll(handler): Integer

Scrolls through model fields and executes a handler on each field.

Model.prototype.serialize(strategy): Object

Converts a model into serialized data object.

Model.prototype.validate({ quiet }): Promise(Model)

Validates model fields, populates the model with possible errors and throws a validation error if not all fields are valid unless the quiet is set to true.

try {
  await model.validate(); // throws a validation error when invalid fields exist
}
catch (e) {
  // `e` is a 422 validation error
}

Field Class

Field({ type, get, set, defaultValue, fakeValue, validate, validators, handle, handlers, owner, failFast })

A model field.

Field.prototype.cast(value): Any

Returns transformed value based on field's type.

Field.prototype.clear(): Field

Sets field and related subfields to null.

Field.prototype.commit(): Field

Sets initial value to the current value. This is how field change tracking is restarted.

Field.prototype.defaultValue: Any

A getter which returns the default field value.

Field.prototype.errors: Object[]

List of field errors (sets the validate method).

Field.prototype.equals(value): Boolean

Returns true when the provided value represents an object that looks the same.

Field.prototype.fake(): Field

Sets field to a generated fake value.

Field.prototype.fakeValue: Any

A getter which returns a fake field value.

Field.prototype.handle(error): Promise(Field)

Validates the value and populates the errors property with errors.

Field.prototype.hasErrors(): Boolean

Returns true when no errors exist (inverse of isValid()). Make sure that you call the validate() method first.

Field.prototype.initialValue: Any

A getter which returns the last committed field value.

Field.prototype.isChanged(): Boolean

Returns true if the field or at least one subfield have been changed.

Field.prototype.isNested(): Boolean

Returns true if the field is a nested model.

Field.prototype.isValid(): Boolean

Returns true if the field and all subfields are valid (inverse of hasErrors()). Make sure that you call the validate() method first.

Field.prototype.invalidate(): Field

Clears the errors field on all fields (the reverse of validate()).

Field.prototype.options: Object

A getter which returns field options.

Field.prototype.owner: Model

A getter which returns a reference to a Model instance on which the field is defined.

Field.prototype.recipe: Object

A getter which returns a field recipe object.

Field.prototype.reset(): Field

Sets the field to its default value.

Field.prototype.rollback(): Field

Sets the field to its initial value (last committed value). This is how you can discharge field's changes.

Field.prototype.type: Any

A getter which returns field type (set to Model for a nested structure).

Field.prototype.validate(): Promise(Field)

Validates the value and populates the errors property with errors.

Field.prototype.value: Any

Field current value (the actual model's property).

Built-in Data Types

NOTE: Field data type should always represent a value. This means that you should never assign a function to a field. If you need to handle dynamic field values, please use field value transformations instead. You can also define your own data type by using the defineType method.

Built-in Validators

absence

Validates that the specified field is blank.

arrayExclusion

Validates that the specified field is not in an array of values.

arrayInclusion

Validates that the specified field is in an array of values.

arrayLength

Validates the size of an array.

block

Validates the specified field against the provided block function. If the function returns true then the field is treated as valid.

const recipe = {
  validator: 'block',
  message: 'must be present',
  async block (value, recipe) { return true },
};

numberSize

Validates the size of a number.

presence

Validates that the specified field is not blank.

stringBase64

Validates that the specified field is base64 encoded string.

stringDate

Validates that the specified field is a date string.

stringEmail

Validates that the specified field is an email.

stringETHAddress

Checks if the string represents an ethereum address.

stringExclusion

Checks if the string does not contain the seed.

stringFQDN

Validates that the specified field is a fully qualified domain name (e.g. domain.com).

stringHexColor

Validates that the specified field is a hexadecimal color string.

stringHexadecimal

Validates that a specified field is a hexadecimal number.

stringInclusion

Checks if the string contains the seed.

stringJSON

Validates that the specified field is a JSON string.

stringLength

Validates the length of the specified field.

stringLowercase

Validates that the specified field is lowercase.

stringMatch

Validates that the specified field matches the pattern.

stringUppercase

Validates that the specified field is uppercase.

stringUUID

Validates that the specified field is a UUID.

Built-in Handlers

block

Checks if the provided block function succeeds.

const recipe = {
  handler: 'block',
  message: 'is unknown error',
  async block (error, recipe) { return true },
};

mongoUniqueness

Checks if the error represents a MongoDB unique constraint error.

const recipe = {
  handler: 'mongoUniqueness',
  message: 'is unknown error',
  indexName: 'uniqueEmail', // make sure that this index name exists in your MongoDB collection
};

License (MIT)

Copyright (c) 2016+ Kristijan Sedlak <xpepermint@gmail.com>

Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated modelation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in
all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
THE SOFTWARE.