View Model

In Presto a ViewModel is a class that defines the list of fields & some metadata for some piece of data (eg. a record from a single database table, some data joined from multiple data sources, a form filled out by a user etc).

It's not specific to a backend implementation rather it's concerned with describing what the data is so that a UI can be generated from it & transformations can be done on the data (eg. from user input to specific format or vice versa).

This package provides the core functionality for defining a ViewModel and using them with a ViewModelCache.

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Installation

Install the packages from npm

yarn add @prestojs/util @prestojs/viewmodel

Usage

Create a ViewModel using viewModelFactory, for example:

import { BooleanField, CharField, EmailField, viewModelFactory } from '@prestojs/viewmodel';

export class User extends viewModelFactory(
    {
        id: new NumberField(),
        firstName: new CharField(),
        lastName: new CharField(),
        email: new EmailField(),
        isActive: new BooleanField({ label: 'Active?' }),
        contactType: new CharField({
            defaultValue: 'lead',
            choices: [
                ['lead', 'Lead'],
                ['contact', 'Contact'],
            ],
        }),
    },
    { pkFieldName: 'id' }
) {
    static label = 'User';
    static labelPlural = 'Users';
}

You can cache instances with ViewModelCache and read from the cache in components using useViewModelCache.