@chialab/schema-model

SchemaModel

Generate Model classes based on JSON Schema definition.

---

Install

npm install @chialab/schema-model --save

Usage

The SchemaModel object can be extended or use as factory to create Model classes dynamically.

Extend the base model

import SchemaModel from '@chialab/schema-model';

class PersonModel extends SchemaModel {
    static get schema() {
        return {
            type: 'object',
            properties: {
                id: {
                    type: 'number',
                },
                firstName: {
                    type: 'string',
                },
                lastName: {
                    type: 'string',
                },
                married: {
                    type: 'boolean',
                },
            },
            required: ['id'],
        };
    }
}

let person = new PersonModel({
    id: 1,
});

As factory

const PersonModel = SchemaModel.create({
    type: 'object',
    properties: {
        id: {
            type: 'number',
        },
        firstName: {
            type: 'string',
        },
        lastName: {
            type: 'string',
        },
        married: {
            type: 'boolean',
        },
    },
    required: ['id'],
});

let person = new PersonModel({
    id: 1,
});

Validation

SchemaModel uses tv4 to validate model data on creation and update.

Get the validation state

Use the .validate method to retrieve the validation state of the model.

let person = new PersonModel();
let validation = person.validate();
console.log(validation.valid); // --> false
console.log(validation.error.message); // --> 'Missing required property: id'

Creation and update

When a set of data is pass to the constructor or to the .set method, the model will try to validate them. If the validation fails, an exception is thrown and the new data will not be set.

try {
    let person = new PersonModel({ firstName: 'Alan' });
} catch (err) {
    console.log(err.message); // --> 'Missing required property: id'
}

try {
    let person = new PersonModel({ id: 1, firstName: 'Alan' });
    person.set({
        lastName: 10,
    });
} catch (err) {
    console.log(err.message); // --> 'Invalid type: number (expected string)'
}

Skip validation

By the way, you can disabled the auto validation passing validate: false as option for constructor/set.

let person = new PersonModel({ firstName: 'Alan' }, { validate: false });
let validation = person.validate();
console.log(validation.valid); // --> false
console.log(validation.error.message); // --> 'Missing required property: id'

Getting and setting data

In order to get an object representing model data, you can use the .toJSON helper, which converts all model instances in javascript plain objects:

let person = new PersonModel({ id: 1, firstName: 'Alan' });
console.log(person); // --> PersonModel{ id: 1, firstName: 'Alan' }
console.log(person.toJSON()); // --> { id: 1, firstName: 'Alan' }

You can access a property of the model using the .get method, or accessing directly to its reference:

let person = new PersonModel({ id: 1, firstName: 'Alan' });
console.log(person.get('id')); // --> 1
console.log(person.firstName); // --> 'Alan'

By the way, you should always use the .set method to update the model:

let person = new PersonModel({ id: 1, firstName: 'Alan' });

// ok!
person.set({
    lastName: 'Turing',
});

// no no no
person.lastName = 'Turing';

Define getters and setters

Using ES2015 classes (or Object.defineProperty programmatically), you can define a custom getter and setter for a property:

import SchemaModel from '@chialab/schema-model';

class PersonModel extends SchemaModel {
    static get schema() {
        return {
            type: 'object',
            properties: {
                id: {
                    type: 'number',
                },
                firstName: {
                    type: 'string',
                },
                lastName: {
                    type: 'string',
                },
                married: {
                    type: 'boolean',
                },
            },
            required: ['id'],
        };
    }

    set married(married) {
        // passing the `internal: true` options you can set a private property.
        this.set('married', !!married, { internal: true });
    }

    get married() {
        // setup a default value for a property
        return this.get('married', { internal: true }) || false;
    }
}

let person = new PersonModel({
    id: 1,
});
console.log(person.married); // --> false
person.set({ married: true });
console.log(person.married); // --> true