Create a policy

Intro

A policy is a class that implements the UCPolicy interface.

Before creating your own, check the policies reference to see if libmodulor does not already provide it. If you don't find your "bonheur" there, check out the example below.

Example

As an example, you can define a policy to allow some use cases only to "Pro" users.

@injectable()
export class ProUCPolicy<
    I extends UCInput | undefined = undefined,
    OPI0 extends UCOPIBase | undefined = undefined,
    OPI1 extends UCOPIBase | undefined = undefined,
> implements UCPolicy<I, OPI0, OPI1>
{
    constructor(
        @inject('UserDataStore') private userDataStore: UserDataStore,
    ) {}

    public async canBeExecutedPreAuth(): Promise<boolean> {
        return false;
    }

    public async exec({
        uc,
    }: UCPolicyInput<I, OPI0, OPI1>): Promise<UCPolicyOutput> {
        const out = defaultUCPolicyOutput();

        const user = await this.userDataStore.get(uc.auth.user.id);
        if (!user) {
            return out;
        }

        out.allowed = user.plan === 'Pro';

        return out;
    }
}

In this example, we get the information from a hypothetical UserDataStore but you are free to inject anything you need in here.