@rawmodel/handler v3.0.0-alpha0

Rawmodel Framework

Rawmodel is a strongly-typed JavaScript object with support for validation and error handling. It's a lightweight open source framework 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.

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 complete control. It could be a perfect fit when writing an Express.js action, GraphQL resolver or similar and it's easily extendable.

Installation

Run the command below to install the package.

$ npm install --save @rawmodel/core
$ npm install --save @rawmodel/handlers // OPTIONAL
$ npm install --save @rawmodel/parsers // OPTIONAL
$ npm install --save @rawmodel/schema // OPTIONAL
$ npm install --save @rawmodel/validators // OPTIONAL

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, prop } from '@rawmodel/core';

// defining a basic model
class User extends Model {
  @prop()
  public name: string;
}

// usage example
const model = new User({
  'name': 'John Smith',
});
model.name; // => 'John Smith'

Usage

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

Defining Props

Model properties are defined using the prop ES6 decorator. The code below is an example of a basic model class with a name property.

import { Model, prop } from '@rawmodel/core';

class User extends Model {
  @prop()
  public name: string;
}

const user = new User();
user.name = 'John Smith';
user.name; // -> "John Smith"

Type Casting

Each property 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.

import { ParserKind } from '@rawmodel/core';
import { stringParser } from '@rawmodel/parsers';

class User extends Model {
  @prop({
    parser: {
      resolver: stringParser(),
    },
  })
  public name: string;
}

Common types are supported by default. A Model also represents a type and you can create your own parsers when needed. Please see the API section for further details.

Nested Models

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

import { Model, ParserKind, prop } from '@rawmodel/core';

class Address extends Model {
  @prop()
  public country: string;
}

class Friend extends Model {
  @prop()
  public name: string;
}

class User extends Model {
  @prop({
    parser: {
      resolver: Address,
    },
  })
  public address: Address;
  @prop({
    parser: {
      array: true,
      resolver: Friend,
    },
  })
  public friends: Friend[];
}

Prop Default Value

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

The defaultValue can also be a method which returns a dynamic value. This function shares the context of the associated model.

@prop({
  defaultValue() { return new Date() },
})
public now: string;

Prop Fake Value

Similar to default values, we can set a fakeValue for each property, to populate a property with fake data when calling the fake() method. This is useful when writting automated tests.

The fakeValue can also be a method which returns a dynamic value. This function shares the context of the associated model.

@prop({
  fakeValue() { return new Date() },
})
public today: string;

Prop Empty Value

By default, all defined properties are set to null. Similar to default and fake values we can set an emptyValue option for each property, to automatically replace null values.

The emptyValue can also be a method which returns a dynamic value. This function shares the context of the associated model.

@prop({
  emptyValue() { return '' },
})
public name: string;

Prop Value Transformation

A property can have a custom getter and a custom setter. This function shares the context of the associated model.

@prop({
  getter(value) { return value },
  setter(value) { return value },
})
public name: string;

Value Assignments

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

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

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

class User extends Model {
  @prop({
    populatable: ['internal'], // list population strategy names
  })
  public id: string;
  @prop({
    populatable: ['input', 'internal'], // list population strategy names
  })
  public name: string;
}

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" }

Model properties also support dynamic data assignments. In translation, this means that we can populate a property using a function that shares the context of the associated model and is realized on property assignment.

user.name = () => 'Join';

It's encouraged to use the populate() method for assigning values unless you know how RawModel works in-depth. Adding items to an array through the native push method, directly assigning model instances and similar data manipulation can lead to strange effects.

Serialization & Filtering

Model provides useful methods for object serialization and filtering. All enumerable properties 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 properties for different situations by using serialization strategies.

class User extends Model {
  @prop({
    serializable: ['output'], // list serialization strategy names
  })
  public id: string;
  @prop({
    serializable: ['input', 'output'], // list serialization strategy names
  })
  public name: string;
}

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" }

A model can also be serialized into an array by using the flatten() method. We can thus easily scroll through all model values in a loop. The method also supports strategies thus we can customize the output and include or exclude properties for different situations.

user.flatten(); // [{ path, value, prop }, ...]
user.flatten('input');
user.flatten('output');

Commits & Rollbacks

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

class User extends Model {
  @prop()
  public name: string;
}

const user = new User();
user.name = 'Mandy Taylor'; // changing property's value
user.isChanged(); // -> true
user.commit(); // set `initialValue` of each property to the value of  `value`
user.isChanged(); // -> false
user.name = 'Tina Fey'; // changing property's value
user.rollback(); // -> reset `value` of each property to its `initialValue` (last committed value)

Note that the commit method will memorize a serialized data and the rollback method will apply it back. Assigning functions or instances to properties is discourages.

Validation

RawModel provides a simple mechanism for validating properties. All validators shares the context of the associated model.

class User extends Model {
  @prop({
    validators: [ // property validation setup
      { // validator recipe
        resolver(v) { return !!v }, // [required] validator function
        code: 422, // [optional] error code
      },
    ],
  })
  public name: string;
}

const user = new User();
user.validate().catch((err) => {
  user.collectErrors(); // -> [{ path: ['name'], code: 422 }]
});

Error Handling

RawModel provides a mechanism for handling property-related errors. The logic is aligned with the validation thus the 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. All handlers shares the context of the associated model.

class User extends Model {
  @prop({
    handlers: [ // property error handling setup
      { // handler recipe
        resolver(e) { return e.message === 'foo' }, // [required] error resolve function
        code: 31000, // [optional] error code
      },
    ],
  })
  public name: string;
}

const error = new Error();
const user = new User();
user.handle(error).then(() => {
  user.collectErrors(); // -> [{ path: ['name'], code: 31000 }]
});

This mechanism is especially handful when saving data to a database. MongoDB database, for example, throws 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() method and then return a unified validation error message to a user.

Raw Schema

JSON Schema is a pretty popular standard for describing JSON objects. It's sufficient for general use cases, but it's not powerful enough to cover all RawModel features. RawModel provides its own schema syntax which allows for the creation of generic models from a JSON definition.

We use createModelClass method to generate a new generic model class from a JSON definition. A model with a single property name could look something like this:

import { createModelClass } from '@rawmodel/schema';

const schema = { // raw model schema
  props: [ // properties definition
    {
      name: 'email', // property name
    },
  ],
};

const Model = createModelClass(schema); // creates model class

We can define static or dynamic default values. Dynamic values must have a resolver under the defaultValues option. If the property's defaultValue matches the resolver name, then the dynamic resolver is applied, otherwise, the static value of the defaultValue is copied. Similar logic applies to getters, setters, fake and empty values.

const schema = {
  defaultValues: {
    currentDate() { return new Date() },
  },
  props: [
    {
      name: 'email',
      defaultValue: 'Noname',
    },
    {
      name: 'date',
      defaultValue: 'currentDate', // referencing currentDate()
    },
  ],
};

Validators and handlers can be defined in a similar way.

import { stringLengthValidator } from '@rawmodel/validators';

const schema = {
  validators: { // schema validators
    stringLength: stringLengthValidator, // validator resolver
  },
  props: [ // schema properties
    { // property definition
      name: 'title', // property name
      validators: [
        {
          resolver: 'stringLength', // validator resolver name
          code: 30001, // validation error code
          options: { min: 5 }, // validator arguments
        },
      ],
    },
  ],
};

Schema supports basically all RawModel features. Check the API section for all the details.

GraphQL

RawModel 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/core';
import { graphql, buildSchema } from 'graphql';

class App extends Model { // root resolver
  public hello() { // `hello` property 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

@rawmodel/core

createModelClass(config)

Create the Model class from a list of property definitions.

const Model = createModelClass([
  {
    name: 'name',
    prop: {
      defaultValue: 'John Smith',
    },
  },
]);

Model(data, config)

Abstract class which represents a strongly-typed JavaScript object.

class User extends Model {
  @prop({
    set(v) { return v; }, // [optional] custom setter
    get(v) { return v; }, // [optional] custom getter
    parser: { // [optional] property type casting
      array: true, // [optional] forces to array conversion when `true`
      resolver: User, // [optional] parser function or Model
    },
    defaultValue: 'Noname', // [optional] property default value (value or function)
    fakeValue: 'Noname', // [optional] property fake value (value or function)
    emptyValue: '', // [optional] property empty value (value or function)
    validators: [ // [optional] value validator recipes
      { // validator recipe (check validatable.js for more)
        resolver(v) { return !!v; }, // [required] validator resolve function (supports async)
        code: 422, // [optional] error code
      },
    ],
    handlers: [ // [optional] error handling recipies
      { // handler recipe
        resolver(e) { return e.message === 'foo'; }, // [required] handler resolve function (supports async)
        code: 31000, // [required] error code
      },
    ],
    populatable: ['input', 'internal'], // [optional] population strategies
    serializable: ['input', 'output'], // [optional] serialization strategies
    enumerable: true, // [optional] when set to `false` the property is not enumerable (ignored by `Object.keys()`)
  })
  public name: string; // [required] typescript property definition
}

Model.@prop(config)

Model property decorator

Model.prototype.__config: Object

Model configuration data.

Model.prototype.__props: Object

Model property instances.

Model.prototype.applyErrors(errors): Model

Deeply populates properties with the provided errors.

model.applyErrors([
  {
    path: ['books', 1, 'title'], // property path
    code: 422, // error code
  },
]);

Model.prototype.clone(data): Model

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

Model.prototype.collectErrors(): Array

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

model.collectErrors(); // => { path: ['name'], code: 300 }

Model.prototype.commit(): Model

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

Model.prototype.empty(): Model

Sets all model properties to null or other empty values.

Model.prototype.fake(): Model

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

Model.prototype.flatten(strategy): Array

Converts the model into an array of properties.

user.flatten(); // -> [{ path, prop, value }, ...]

Model.prototype.freeze(): Model

Makes each model property not settable.

Model.prototype.getAncestors(): Model[]

Returns a list of all parent model instances.

Model.prototype.getContext(): Context

Returns model context data.

Model.prototype.getParent(): Model

Returns the parent model instance in a tree of models.

Model.prototype.getProp(...keys): Prop

Returns a class instance of a property at path. Note that array values do not have properties but refer to object property.

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

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

try {
  await model.validate(); // imagine it throws an error
} catch (e) {
  await model.handle(e);
}

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

Returns true when a property path exists. Note that array values do not have properties but refer to object property.

Model.prototype.isChanged(): Boolean

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

Model.prototype.isEqual(value): Boolean

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

Model.prototype.isValid(): Boolean

Returns true when all model properties are valid. Make sure that you call the validate() method first.

Model.prototype.invalidate(): Model

Clears errors on all properties.

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

Populates enumerable properties with data.

Model.prototype.reset(): Model

Sets each model property to its default value.

Model.prototype.rollback(): Model

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

Model.prototype.serialize(strategy): Object

Converts a model into serialized data object. The result will include only enumerable properties.

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

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

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

Prop(config)

A model property.

Prop.prototype.__config: Object

Property configuration object.

Prop.prototype.empty(): Prop

Sets property and related sub-properties to null.

Prop.prototype.commit(): Prop

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

Prop.prototype.fake(): Prop

Sets property to a generated fake value.

Prop.prototype.freeze(): Prop

Makes property not settable.

Prop.prototype.getErrorCode(): Number

Returns property error code (sets the validate method).

Prop.prototype.getInitialValue(): Any

Returns property initial value.

Prop.prototype.getValue(): Any

Returns current property value.

Prop.prototype.getRawValue(): Any

Returns current property raw value.

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

Handles the error and populates the property with error.

Prop.prototype.isArray(): Boolean

Returns true if the property is an array.

Prop.prototype.isEmpty(): Boolean

Returns true if the property has no value.

Prop.prototype.isEqual(value): Boolean

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

Prop.prototype.isChanged(): Boolean

Returns true if the property or at least one sub-property have been changed.

Prop.prototype.isPopulatable(strategy): Boolean

Returns true if the property can be set.

Prop.prototype.isSerializable(strategy): Boolean

Returns true if the property can be serialized.

Prop.prototype.isValid(): Boolean

Returns true if the property and all sub-properties are valid (inverse of hasErrors()). Make sure that you call the validate() method first.

Prop.prototype.invalidate(): Prop

Clears the property error (the reverse of validate()).

Prop.prototype.reset(): Prop

Sets the property to its default value.

Prop.prototype.rollback(): Prop

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

Prop.prototype.serialize(strategy)

Returns a serialized property value. Note that only enumerable properties are serializable.

Prop.prototype.setValue(value)

Sets current property value.

Prop.prototype.validate(): Promise(Prop)

Validates the value and populates the property with error.

@rawmodel/schema

createModelClass(recipe):Class

Returns a new generic model class build from the provided schema recipe.

const Model = createModelClass({
  getters: {
    customGetter(options: any) { // custom getter function which returns a resolver
      return function(v: any) { return v; } // context aware resolver
    },
  },
  setters: {}, // see getters
  defaultValues: {
    dynamicValue(options: any) { // custom default value function which returns a resolver
      return function(v: any) { return v; } // context aware resolver
    },
    staticValue(options: any) { // custom default value function which returns a static value
      return 'foo';
  },
  fakeValues: {}, // see defaultValues
  emptyValues: {}, // see defaultValues
  parsers: {
    toString() { // custom parser function which returns a resolver
      return function(v: any) { return v.toString(); }; // context aware resolver
    },
  },
  validators: {
    isPresent() { // custom validator function which returns a resolver
      return function(v: any) { return !!v }; // context aware resolver (function or promise)
    },
  };
  handlers: {}, // see validators
  props: [
    name: 'firstName', // property name
    getter: 'customGetter', // getter name (defined in `getters`)
    setter: 'customSetter', // setter name (defined in `setters`)
    parser: {
      array: true, // when `true` the input is converted to array
      resolver: 'toString', // parser resolver name
    },
    defaultValue: 'none', // static default value
    fakeValue: 'none', // static fake value
    emptyValue: '', // static empty value
    validators: [
      {
        code: 30001, // validator error code
        resolver: 'isPresent', // validator resolver name
      },
    ],
    handlers: [], // see validators
    populatable: ['input', 'db'], // populatable strategies
    serializable: ['input', 'db'], // serializable strategies
    enumerable: true, // property is enumerable
  ],
});

@rawmodel/parsers

NOTE: Every model can be used as a parser resolver.

booleanParser(): Function

Converts a value to a boolean value.

const recipe = {
  array: true, // optional
  resolver: booleanParser(),
}

bsonObjectIdStringParser(): Function

Converts a value to a valid BSON ObjectId string.

dateParser(): Function

Converts a value to a date object.

floatParser(): Function

Converts a value to a decimal number.

integerParser(): Function

Converts a value to an integer number.

stringParser: Function

Converts a value to a string.

@rawmodel/validators

Please note that the validators do not trigger if no value is present (on undefined or null). Make sure your custom validators follow the same concept. The exception are validators which verify value presence or absence.

absenceValidator(): Function

Validates that the specified property is blank.

import { absenceValidator } from '@rawmodel/validators';

const recipe = {
  resolver: absenceValidator(),
  code: 422,
};

arrayExclusionValidator(options): Function

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

arrayInclusionValidator(options): Function

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

arrayLengthValidator(options): Function

Validates the size of an array.

base64Validator(): Function

Validates that the specified property is base64 encoded string.

bsonObjectIdValidator(): Function

Validates that the specified property is BSON ObjectId encoded string.

dateValidator(options): Function

Validates that the specified property is a date string.

downcaseStringValidator(): Function

Validates that the specified property is lowercase.

emailValidator(options): Function

Validates that the specified property is an email.

ethAddressValidator(): Function

Checks if the string represents an Ethereum address.

exclusionValidator(options): Function

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

fqdnValidator(options): Function

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

hexColorValidator(): Function

Validates that the specified property is a hexadecimal color string.

hexValidator(): Function

Validates that a specified property is a hexadecimal number.

inclusionValidator(options): Function

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

jsonStringValidator(options): Function

Validates that the specified property is a JSON string.

matchValidator(options): Function

Validates that the specified property matches the pattern.

numberSizeValidator(options): Function

Validates the size of a number.

presenceValidator(): Function

Validates that the specified property is not blank.

stringExclusionValidator(options): Function

Checks if the string does not contain the seed.

stringInclusionValidator(): Function

Checks if the string contains the seed.

stringLengthValidator(options): Function

Validates the length of the specified property.

upcaseStringValidator(): Function

Validates that the specified property is uppercase.

uuidValidator(options): Function

Validates that the specified property is a UUID.

@rawmodel/handlers

mongoUniquenessHandler(options): Function

Checks if the error represents a MongoDB unique constraint error.

import { mongoUniquenessHandler } from '@rawmodel/handlers';

const recipe = { // make sure that this index name exists in your MongoDB collection
  resolver: mongoUniquenessHandler({ indexName: 'uniqueEmail' }),
  code: 422,
};

Packages

Package	Description	Version
@rawmodel/core	Model and property classes.
@rawmodel/handlers	Collection of error handlers.
@rawmodel/parsers	Collection of data parsers.
@rawmodel/schema	JSON Schema utils.
@rawmodel/utils	Helper functions.
@rawmodel/validators	Collection of validators.

Contributing

See CONTRIBUTING.md for how to help out.

Licence

See LICENSE for details.