# registerLocalModules

This function is deprecated, use the bootstrap function instead.

Register one or many local module(s). During the registration process, the specified registration function will be invoked with a FireflyRuntime instance and an optional context object. To defer the registration of specific navigation items, a registration function can return an anonymous function.

A local module is a regular module that is part of the host application build and is bundled at build time, as opposed to a remote module which is loaded at runtime from a remote server. Local modules are particularly valuable when launching a new product with an evolving business domain or when undergoing a migration from a monolithic application to a federated application.

# Reference

registerLocalModules(registerFunctions: [], runtime, options?: { context? })

# Parameters

registerFunctions: An array of ModuleRegisterFunction.
runtime: A FireflyRuntime instance.
options: An optional object literal of options:
- context: An optional context object that will be pass to the registration function.

# Returns

A Promise object with an array of LocalModuleRegistrationError if any error happens during the registration.

# `LocalModuleRegistrationError`

error: The original Error object.

# Usage

# Register a local module

host/src/bootstrap.tsx
import { registerLocalModules, FireflyRuntime } from "@squide/firefly";
import { register } from "@sample/local-module";

const runtime = new FireflyRuntime();

await registerLocalModules([register], runtime);

local-module/src/register.tsx
import type { ModuleRegisterFunction, FireflyRuntime } from "@squide/firefly";
import { AboutPage } from "./AboutPage.tsx";

export const register: ModuleRegisterFunction<FireflyRuntime> = runtime => {
    runtime.registerRoute({
        path: "/about",
        element: <AboutPage />
    });

    runtime.registerNavigationItem({
        $id: "about",
        $label: "About",
        to: "/about"
    });
}

Sometimes, data must be fetched to determine which navigation items should be registered by a given module. To address this, Squide offers a two-phase registration mechanism:

The first phase allows modules to register their navigation items that are not dependent on initial data (in addition to their routes and MSW request handlers when fake endpoints are available).
The second phase enables modules to register navigation items that are dependent on initial data. Such a use case would be determining whether a navigation item should be registered based on a feature flag. We refer to this second phase as deferred registrations.

To defer a registration to the second phase, a module registration function can return an anonymous function matching the DeferredRegistrationFunction type: (data, operation: "register" | "update") => Promise | void.

Once the modules are registered, the deferred registration functions will be executed with the deferred data and "register" as the value for the operation argument. Afterward, whenever the deferred data changes, the deferred registration functions will be re-executed with the updated deferred data and "update" as the value for the operation argument.

host/src/bootstrap.tsx
import { FireflyRuntime, registerLocalModules, RuntimeContext } from "@squide/firefly";
import { createRoot } from "react";
import { register } from "@sample/local-module";
import { App } from "./App.tsx";

const runtime = new FireflyRuntime();

await registerLocalModules([register], runtime);

const root = createRoot(document.getElementById("root")!);

root.render(
    <RuntimeContext.Provider value={runtime}>
        <App />
    </RuntimeContext.Provider>
);

host/src/AppRouter.tsx
import { usePublicDataQueries, useDeferredRegistrations, useIsBootstrapping, AppRouter as FireflyAppRouter } from "@squide/firefly";
import { useMemo } from "react";
import { RouterProvider, createBrowserRouter, Outlet } from "react-router-dom";
import type { DeferredRegistrationData } from "@sample/shared";
import { getFeatureFlagsQuery } from "./getFeatureFlagsQuery.ts";

function BootstrappingRoute() {
    const [featureFlags] = usePublicDataQueries([getFeatureFlagsQuery]);

    // The useMemo is super important otherwise the hook will consider that the feature flags
    // changed everytime the hook is rendered.
    const data: DeferredRegistrationData = useMemo(() => ({ 
        featureFlags 
    }), [featureFlags]);

    useDeferredRegistrations(data);

    if (useIsBootstrapping()) {
        return <div>Loading...</div>;
    }

    return <Outlet />;
}

export function AppRouter() {
    return (
        <FireflyAppRouter waitForMsw={false} waitForPublicData>
            {({ rootRoute, registeredRoutes, routerProviderProps }) => {
                return (
                    <RouterProvider
                        router={createBrowserRouter([
                            {
                                element: rootRoute,
                                children: [
                                    {
                                        element: <BootstrappingRoute />,
                                        children: registeredRoutes
                                    }
                                ]
                            }
                        ])}
                        {...routerProviderProps}
                    />
                );
            }}
        </FireflyAppRouter>
    );
}

Routes are always registered, but navigation items can be conditionally registered using a deferred registration function.

local-module/src/register.tsx
import type { ModuleRegisterFunction, FireflyRuntime } from "@squide/firefly";
import type { DeferredRegistrationData } from "@sample/shared";
import { AboutPage } from "./AboutPage.tsx";
import { FeatureAPage } from "./FeatureAPage.tsx";

export const register: ModuleRegisterFunction<FireflyRuntime, unknown, DeferredRegistrationData> = runtime => {
    runtime.registerRoute({
        path: "/about",
        element: <AboutPage />
    });

    runtime.registerNavigationItem({
        $id: "about",
        $label: "About",
        to: "/about"
    });

    // Routes are always registered. If a route may not be available for a group of users, conditionally register
    // its navigation item with a deferred registration.
    // To manage direct hits to a conditional route, render an error boundary whenever the route's endpoint returns a 401 status code.
    runtime.registerRoute({
        path: "/feature-a",
        element: <FeatureAPage />
    });

    // Once the feature flags has been loaded by the host application, by completing the module registrations process,
    // the deferred registration function will be called with the feature flags data.
    return ({ featureFlags }) => {
        // Only register the "feature-a" route and navigation item if the feature is active.
        if (featureFlags.featureA) {
            runtime.registerNavigationItem({
                $id: "feature-a",
                $label: "Feature A",
                to: "/feature-a"
            });
        }
    };
}

useDeferredRegistrations

../usedeferredregistrations/

# Use the deferred registration operation argument

local-module/src/register.tsx
import type { ModuleRegisterFunction, FireflyRuntime } from "@squide/firefly";
import type { DeferredRegistrationData } from "@sample/shared";
import { AboutPage } from "./AboutPage.tsx";
import { FeatureAPage } from "./FeatureAPage.tsx";

export const register: ModuleRegisterFunction<FireflyRuntime, unknown, DeferredRegistrationData> = runtime => {
    runtime.registerRoute({
        path: "/about",
        element: <AboutPage />
    });

    runtime.registerNavigationItem({
        $id: "about",
        $label: "About",
        to: "/about"
    });

    // Routes are always registered. If a route may not be available for a group of users, conditionally register
    // its navigation item with a deferred registration.
    // To manage direct hits to a conditional route, render an error boundary whenever the route's endpoint returns a 401 status code.
    runtime.registerRoute({
        path: "/feature-a",
        element: <FeatureAPage />
    });

    // Once the feature flags has been loaded by the host application, by completing the module registrations process,
    // the deferred registration function will be called with the feature flags data.
    return ({ featureFlags }, operation) => {
        // Only register the "feature-a" route and navigation item if the feature is active.
        if (featureFlags.featureA) {
            runtime.registerNavigationItem({
                $id: "feature-a",
                $label: operation === "register" ? "Feature A" : "Feature A updated",
                to: "/feature-a"
            });
        }
    };
}

# Handle registration errors

host/src/bootstrap.tsx
import { registerLocalModules, FireflyRuntime } from "@squide/firefly";
import { register } from "@sample/local-module";

const runtime = new FireflyRuntime();

(await registerLocalModules([register], runtime)).forEach(x => {
    console.error(x);
});