convict-model

Convict Model

Annotate a class to define and validate your configs using convict just like you do with an ORM. If you like annotating models classes, then this package will tickle your fancy. The code style and patterns are based on Typeorm because they know what's up. If your using a IOC/DI system, ConvictModel will fit in real nice.

Requirements

• NodeJS 8+
• Typescript 3+
• Convict 5+

Quick Links

Contributing	Changelog	Convict

Installation

• Install the package

npm install @akirix/convict-model --save

• Install reflect-metadata if you have not already so the annotations work.

npm install reflect-metadata --save

then import it in global scope aka main file, i.e. app.ts or index.ts

import "reflect-metadata";

• Now we install convict and its types so you can control the version

npm install convict --save
npm install @types/convict --save-dev

• Make sure annotations are enabled in tsconfig.json

"emitDecoratorMetadata": true,
"experimentalDecorators": true,

• (optional) Install JS Yaml if you like yaml over json for configs.

npm install js-yaml --save

Project Setup

First we need a proper project setup like the one below with a folder to hold our config schema classes. This is a very simple Typescript folder structure.

MyProject
├── src                  // place of your TypeScript code
│   ├── schema           // place where your config entities will go
│   │   ├── MyConfig.ts  // sample entity
│   │   └── SubConfig.ts // a nested entity
│   ├── types.d.ts       // place to put your interfaces  
│   └── index.ts         // start point of your application
├── .gitignore           // standard gitignore file
├── config.json          // Your apps config file
├── package.json         // node module dependencies
├── README.md            // a readme file
└── tsconfig.json        // TypeScript compiler options

Take note of the src/schema directory, here we will put our config schema classes which will be annotated with convict schema definitions. This directory can be called whatever you like by the way. Technically you don't even need the folder, it's just a good idea to put similar classes together for organization.

Getting Started

Now we can start building up a model for our config schema.

1. Define an Interface

It's a good idea to define an interface so your experience can be agile and include all the fancy IDE features. Interfaces also open an opportunity to have more than one implementation of your config, i.e. maybe you use convict competitor or no validation on config at all.

src/types.d.ts

declare namespace config {
    export interface MyConfig {
        name: string;
        subConfig: SubConfig;
    }
    export interface SubConfig {
        bar: number;
    }
}

2. Define a Schema Class

Now we can define a schema class and decorate it like Christmas. The parameter for @Property decorator is simply a convict SchemaObj like in normal convict. You can read all about the possible options in convicts documentation.

src/schema/MyConfig.ts

import { Property } from '@akirix/convict-model';
import SubConfig from './SubConfig';
import * as yaml from 'js-yaml';

@Config({
    as: 'foo',// an alias for the config file, i.e base name
    dir: 'config',// relative to NODE_PATH or cwd()
    parser: { 
        extension: ['yml', 'yaml'], 
        parse: yaml.safeLoad
    }
})
export default class MyConfig implements config.MyConfig {
    
    @Property({
        doc: 'The name of the thing',
        default: 'Convict',
        env: 'MY_CONFIG_NAME'
    })
    public name: string;

    @Property(SubConfig)
    public subConfig: SubConfig;

}

src/schema/SubConfig.ts

export default class SubConfig {
    @Property({
        doc: 'A sub prop',
        default: 3,
        env: 'SUB_CONFIG_BAR',
        format: 'int'
    })
    public bar: number;
}

3. Make a Configuration

Now we can make our configuration for our app. This can be a hardcoded Object in your code, a json file, a yaml file, or however you do it. In the end it's up to you how you type out and load the data.

config.json

{
    "name": "Cool App",
    "subConfig": {
        "bar": 5
    }
}

4. Load it up

We have a couple of ways to load it up so you can choose what works for your unique situation. The example below is the simplest way in the spirit of TL;DR.

src/index.ts

import { getConvictModel, ConvictModel } from '@akirix/convict-model';

//get your config file however you do it
const myRawConfig = getMyConfigData();

//initialize the ConvictModel with a list of paths or entities to load as the schema
const convictModel: ConvictModel = getConvictModel(['src/schema/**/*.*s']);

//get your validated config object as a serialized class
const myConfig: config.MyConfig = convictModel.create<config.MyConfig>('MyConfig',myRawConfig);