ModelGen 🎰

ModelGen is a command-line tool for generating models from JSON Schemas.

Why?

Models are usually boilerplate code, why not generate them and forget? It will save you time writing boilerplate and eliminate model errors as your application scales in complexity.

This means that adding a property to a data object is truly a one-line change — no copy-paste required. If you want to refactor all your models it is simple as changing the template and regenerate them.

How?

Unlike most of the model generators, it works with two files, the .json and .stencil so you have full control on how you want your models to look like.

The Models are defined in JSON, based on JSON Schema but not limited to, basically anything you add on schema you can use the template. It is an extensible and language-independent specification.

Examples?

Take a look at Example folder.

Installation

For now you can build from source:

$ git clone https://github.com/hebertialmeida/ModelGen.git
$ cd ModelGen
$ rake cli:install

Defining a schema

ModelGen takes a schema file as an input.

{
  "title": "Company",
  "type": "object",
  "description": "Definition of a Company",
  "identifier": "id",
  "properties": {
    "id": {"type": "integer"},
    "name": {"type": "string"},
    "logo": {"type": "string", "format": "uri"},
    "subdomain": {"type": "string"}
  },
  "required": ["id", "name", "subdomain"]
}

Defining a template

ModelGen takes a template to generate in the format you want.

//
//  {{ spec.title }}.swift
//  ModelGen
//
//  Generated by [ModelGen]: https://github.com/hebertialmeida/ModelGen
//  Copyright © {% now "yyyy" %} ModelGen. All rights reserved.
//

{% if spec.description %}
/// {{ spec.description }}
{% endif %}
public struct {{ spec.title }}: Equatable {
{% for property in spec.properties %}
{% if property.doc %}
    /**
     {{ property.doc }}
     */
{% endif %}
    public let {{ property.name }}: {{ property.type }}{% if not property.required %}?{% endif %}
{% endfor %}

    // MARK: - Initializers

{% map spec.properties into params using property %}{{ property.name }}: {{ property.type }}{% if not property.required %}?{% endif %}{% endmap %}
    public init({{ params|join:", " }}) {
{% for property in spec.properties %}
        self.{{ property.name }} = {{ property.name }}
{% endfor %}
    }

// MARK: - Equatable

public func == (lhs: {{spec.title}}, rhs: {{spec.title}}) -> Bool {
{% for property in spec.properties %}
    guard lhs.{{property.name}} == rhs.{{property.name}} else { return false }
{% endfor %}
    return true
}

Generating models

To make it easy you can create a .modelgen.yml

spec: ../Specs/
output: ./Model/
template: template.stencil
language: swift # Only swift is supported right know

And then:

$ modelgen

Without the .modelgen.yml file

Generate from a directory:

$ modelgen --spec ./Specs --template template.stencil --output ./Model

Generate a single file:

$ modelgen --spec company.json --template template.stencil --output Company.swift

Generated output

//
//  Company.swift
//  ModelGen
//
//  Generated by [ModelGen]: https://github.com/hebertialmeida/ModelGen
//  Copyright © 2017 ModelGen. All rights reserved.
//

/// Definition of a Company
public struct Company: Equatable {
    public let subdomain: String
    public let name: String
    public let logo: URL?
    public let id: Int

    // MARK: - Initializers

    public init(subdomain: String, name: String, logo: URL?, id: Int) {
        self.subdomain = subdomain
        self.name = name
        self.logo = logo
        self.id = id
    }

// MARK: - Equatable

public func == (lhs: Company, rhs: Company) -> Bool {
    guard lhs.subdomain == rhs.subdomain else { return false }
    guard lhs.name == rhs.name else { return false }
    guard lhs.logo == rhs.logo else { return false }
    guard lhs.id == rhs.id else { return false }
    return true
}

Attributions

This tool is powered by:

• Stencil and few other libs by Kyle Fuller
• StencilSwiftKit by SwiftGen

The inital concept was based on Peter Livesey's pull request and inspired by plank from Pinterest.

If you want to contribute, don't hesitate to open an pull request.

License

ModelGen is available under the MIT license. See the LICENSE file.