SchemaModel
Generate Model classes based on JSON Schema definition.
---
## Install
```sh
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
```js
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
```js
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](https://github.com/geraintluff/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.
```js
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.
```js
try {
let person = new PersonModel({ firstName: 'Alan' });
} catch (err) {
console.log(err.message); // --> 'Missing required property: id'
}
```
```js
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.
```js
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:
```js
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:
```js
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:
```js
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:
```js
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
```