enforce-custom-provider-type.md

description
Enforces a styleguide for provider types

Large teams can have the desire to limit or enforce a particular style of creating custom providers; e.g. banning request-scoped providers to avoid potential circular dependencies, or preferring factory providers over value providers to significantly increase performance. This rule enforces a particular type of provider to be used.

Options

This rule accepts an object with the "prefer" property, which is an array containing one or more of the following values:

• value: Enforces the use of value providers.
• factory: Enforces the use of factory providers.
• class: Enforces the use of class providers.
• existing: Enforces the use of existing providers.

Example of Options

"rules": {
  "@trilon/enforce-custom-provider-type": [ 
   "warn", {  
     "prefer": ["factory", "value"]
   }
  ]
}

Examples

Considering the options above, the following examples will show how the rule behaves when the prefer option is set to factory.

❌ Incorrect

const customValueProvider: Provider = {
  provide: 'TOKEN',
  useExisting: 'some-value' // ⚠️ provider is not of type ["factory", "value"]
}

const customClassProvider: Provider = {
  provide: AbstractClass,
  useClass: SomeClass  // ⚠️ provider is not of type ["factory", "value"]
}

✅ Correct

const factoryProvider: Provider = { provide: 'TOKEN', useFactory: () => 'some-value' }

When Not To Use It

If you don't want to enforce a particular style of provider, you can disable this rule.