Models for NorJS

Abstracts, factories and utils for implementing classes in ES6 JavaScript.

Also includes some NorJS concrete model classes, which are also examples of usage.

Package usage

Requirements

• Babel 7 with ES6 support (building)
• Lodash
• Support for symbols

Install in your project

npm i --save-dev @norjs/models

Import

For eg. DataModel, use:

import { DataModel } from "@norjs/models";

Run tests

npm test

DataModel

The abstract base class for models.

As an abstract class it does not work unless you extend from it and define missing abstract methods, or use one of our ready to use classes.

See also:

• InternalDataModel,
• PlainDataModel,
• ShallowCowDataModel,
• DataModel.create(model)
• DataModel.deleteProperty(model, key),
• Invoice,
• InvoiceRow

You can also compose your own classes a bit by bit using our factory functions:

• InternalDataModelFactory,
• PlainDataModelFactory,
• ShallowCowDataModelFactory
• InvoiceFactory
• InvoiceRowFactory

These factory functions make it possible to swap parts of the implementation, or use your own instead.

DataModel.create(model)

Static, public.

This is a static method which you can use to create a freezed instance of your model.

You need to call it from your own class, of course.

Eg. if your class is MyData extends DataModel, you'll call it as const model = MyData.create(...)

DataModel.deleteProperty(obj, key)

Static, public.

Delete a property inside the model by a keyword.

Note! It is recommended to save your keywords as static constants into your model class, so user's don't need to use your internal keyword strings or symbols to delete properties.

DataModel#valueOf()

Public.

Returns the internal value for the model. Usually it is an object.

DataModel#getId()

Abstract, Public.

Returns the unique identifier value for this model instance. (Eg. the primary key in a database table.)

DataModel#setId(value)

Abstract, Public.

Sets the unique identifier value for this model instance. (Eg. the primary key in a database table.)

DataModel#constructor(value)

Protected.

The constructor, which is declared as protected to disable using new DataModel () style.

DataModel#_getInternal()

Returns the internal value for the model. Usually it is an object.

Abstract, protected.

DataModel#_setInternal(value)

Abstract, Protected.

Sets the internal value of the model. Usually it's an object.

DataModel#_has(key)

Abstract, Protected.

Returns true or false depending if a keyword is defined in the model's internal value.

See DataModel#_get(key) for more information for the keyword format.

DataModel#_get(key)

Abstract, Protected.

Returns the value for a property from the model's internal value.

The key can be:

• a symbol for the value, eg FOO for .valueOf()[FOO]
• a string with a path to the property, eg. "foo.bar" for .valueOf().foo.bar
• an array of symbol or string values, eg. ["foo", "bar"] for .valueOf().foo.bar

DataModel#_set(key, value)

Abstract, Protected.

Sets a value for a property in the model's internal value.

See DataModel#_get(key) for more information for the keyword format.

DataModel#_delete(key)

Abstract, Protected.

Delete a value for a property in the model's internal value.

See DataModel#_get(key) for more information for the keyword format.

InternalDataModel

This is an abstract class extended from DataModel which has implemented interface to get and set an internal model value as a plain object.

It implements:

• DataModel#constructor(value = {}) using DataModel#_setInternal(value)
• DataModel#_getInternal()
• DataModel#_setInternal(value).

It does not implement:

• DataModel#_has(key)
• DataModel#_get(key)
• DataModel#_set(key, value)
• DataModel#_delete(key)
• DataModel#getId()
• DataModel#setId(value)

InternalDataModelFactory

This is a factory function which returns a class extending to the provided DataModel class and implementing DataModel#_getInternal() and DataModel#_setInternal(value) using a private member variable.

class MyData extends InternalDataModelFactory(DataModel) {
	// ...
}

You'll need to implement other abstract methods.

See also InternalDataModel.

PlainDataModel

This is an abstract class extended from InternalDataModel which has implemented interface to get and set an internal model value as a plain object.

It implements:

• DataModel#_has(key)
• DataModel#_get(key)
• DataModel#_set(key, value)
• DataModel#_delete(key)

It also implements:

• DataModel#_getInternal() (from InternalDataModel)
• DataModel#_setInternal(value) (from [InternalDataModel] (#InternalDataModel))

It does not implement:

• DataModel#getId()
• DataModel#setId(value)

PlainDataModelFactory

This is a factory function which returns a class extended from the provided model class implementing DataModel#_has(key), DataModel#_get(key), DataModel#_set(key, value) and DataModel#_delete(key).

It implements them using DataModel#_getInternal() and DataModel#_setInternal(value), which must be implemented in the provided model or later in your own class.

class MyData extends PlainDataModelFactory(DataModel) {
	// ...
}

See also PlainDataModel and ShallowCowDataModel for ready to use abstract classes.

ShallowCowDataModel

This is a class extended from PlainDataModel which implements abstract shallow copy on write model class implementation.

The shallow copy will be made only when there is a write operation and only to the parent objects of the modified property.

You can trust that the internal object returned from a call to #valueOf() will not be modified later (by the model class implementation). It also will not be deep copied when returned since this is a copy on write, not copy on read implementation.

Later call to #valueOf() may return a different object, but only if it was modified, and only modified inner objects (and their parents) will point to new copies. Eg. a change in a property of "foo.bar" does not modify a reference of an object in "bar.foo".

It re-implements:

• DataModel#_set(key, value)
• DataModel#_delete(key)

It also implements:

• DataModel#_has(key) (from PlainDataModel)
• DataModel#_get(key) (from PlainDataModel)
• DataModel#_getInternal() (from InternalDataModel)
• DataModel#_setInternal(value) (from [InternalDataModel] (#InternalDataModel))

It does not implement:

• DataModel#getId()
• DataModel#setId(value)

ShallowCowDataModelFactory

This is a factory function which returns a class extended from the provided model class implementing DataModel#_set(key, value) and DataModel#_delete(key).

It implements them using abstract DataModel#_setInternal(value), which you need to implement.

class MyData extends ShallowCowDataModelFactory(DataModel) {
	// ...
}

It does not implement:

• DataModel#_has(key)
• DataModel#_get(key)
• DataModel#_getInternal()
• DataModel#_setInternal(value)
• DataModel#getId()
• DataModel#setId(value)

See also ShallowCowDataModel for ready to use abstract class.

Invoice

This is our invoice model class. See the source code for updated inline documentation.

InvoiceFactory

This is our invoice model factory function. See the source code for updated inline documentation.

InvoiceRow

This is our invoice row model class. See the source code for updated inline documentation.

InvoiceRowFactory

This is our invoice row model factory function. See the source code for updated inline documentation.

DataModelUtils

DataModelUtils.getPathToProperty(model, key)

Returns a readable and writable interface to a property inside the model object.

DataModelUtils.shallowCopyByPath(model, path)

Returns a new model object with the path shallow copied to the property.