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+

$3

Contributing | Changelog | Convict |
|---|---|---|

Installation

1. Install the package

npm install @akirix/convict-model --save

2. 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";

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

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

4. Make sure annotations are enabled in tsconfig.json

``json
"emitDecoratorMetadata": true,
"experimentalDecorators": true,
`

5. (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.

$3

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

$3

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

$3

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

$3

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
`typescript
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('MyConfig',myRawConfig);

``