Hooks

Concerns offer a few hook methods. These can be used to perform advanced setup or initialisation logic.

• BEFORE Registration
• AFTER Registration

BEFORE Registration

To perform pre-registration logic, use the static BEFORE method in your concern class. This hook method is invoked before the concern container and aliases are defined in the target class.

The method accepts the following arguments:

• target: UsesConcerns - the target class (class constructor!).

import { BEFORE } from "@aedart/contracts/support/concerns";
import { AbstractConcern } from "@aedart/support/concerns";
import { isSubclass } from '@aedart/support/reflections';

import { JobHandler } from '@acme/jobs';

class RecordsJobs extends AbstractConcern {
    
    static [BEFORE](target) {
        // E.g. prevent this concern from being used by all kinds of targets...
        if (!isSubclass(target, JobHandler)) {
            throw new TypeError('RecordsJobs can only be used by JobHandler');
        }
    }
}

AFTER Registration

To perform post-registration logic, use the static AFTER method in your concern class. This method is invoked after the concern container and aliases have been defined in target's prototype.

The method accepts the following arguments:

• target: UsesConcerns - the target class (class constructor!).

import { AFTER } from "@aedart/contracts/support/concerns";
import { AbstractConcern } from "@aedart/support/concerns";

import { ApiConnection } from '@acme/api';

class RecordsJobs extends AbstractConcern {
    
    static [AFTER](target) {
        // E.g. init or setup static resources...
        ApiConnection.init();
    }
}