Improve types of getFixedT

sergiodxa · Aug 7, 2024 · dfb2309 · dfb2309
1 parent d247a1a
commit dfb2309
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Showing 3 changed files with 55 additions and 34 deletions.
diff --git a/package.json b/package.json
@@ -55,13 +55,7 @@
 	},
 	"funding": "https://github.com/sponsors/sergiodxa",
 	"homepage": "https://github.com/sergiodxa/remix-i18next#readme",
-	"keywords": [
-		"remix",
-		"i18n",
-		"i18next",
-		"ssr",
-		"csr"
-	],
+	"keywords": ["remix", "i18n", "i18next", "ssr", "csr"],
 	"license": "MIT",
 	"peerDependenciesMeta": {
 		"@remix-run/cloudflare": {

diff --git a/src/server.test.ts b/src/server.test.ts
@@ -252,7 +252,7 @@ describe(RemixI18Next.name, () => {
 		let backendPlugin: BackendModule = {
 			type: "backend",
 			init: () => null,
-			read: (_language, _namespace, callback) => {
+			read(_language, _namespace, callback) {
 				callback(null, {
 					hello: "Hello {{name, uppercase}}",
 					user: { age: "My age is {{number}}" },
@@ -265,7 +265,7 @@ describe(RemixI18Next.name, () => {
 			init: () => null,
 			add: () => null,
 			addCached: () => null,
-			format: (value, format) => {
+			format(value, format) {
 				if (format === "uppercase") return value.toUpperCase();
 			},
 		};
@@ -299,6 +299,7 @@ describe(RemixI18Next.name, () => {
 
 			let t = await i18n.getFixedT(request, "common");
 
+			// @ts-expect-error - We're not using the typed resources here
 			expect(t("Hello {{name}}", { name: "Remix" })).toBe("Bonjour Remix");
 		});
 
@@ -396,3 +397,14 @@ describe(RemixI18Next.name, () => {
 		});
 	});
 });
+
+declare module "i18next" {
+	interface CustomTypeOptions {
+		resources: {
+			common: {
+				hello: string;
+				user: { age: string };
+			};
+		};
+	}
+}
diff --git a/src/server.ts b/src/server.ts
@@ -5,7 +5,10 @@ import type {
 } from "@remix-run/server-runtime";
 import {
 	type BackendModule,
+	type DefaultNamespace,
+	type FlatNamespace,
 	type InitOptions,
+	type KeyPrefix,
 	type Module,
 	type Namespace,
 	type NewableModule,
@@ -15,7 +18,11 @@ import {
 import { getClientLocales } from "./lib/get-client-locales.js";
 import { pick } from "./lib/parser.js";
 
-const DEFAULT_NS: Namespace = "translation";
+type FallbackNs<Ns> = Ns extends undefined
+	? DefaultNamespace
+	: Ns extends Namespace
+		? Ns
+		: DefaultNamespace;
 
 export interface LanguageDetectorOption {
 	/**
@@ -144,47 +151,55 @@ export class RemixI18Next {
 	 * @param namespaces The namespaces to use for the T function. (Default: `translation`).
 	 * @param options The i18next init options and the key prefix to prepend to translation keys.
 	 */
-	async getFixedT<N extends Namespace, KPrefix extends string = "">(
+	async getFixedT<
+		N extends
+			| FlatNamespace
+			| readonly [FlatNamespace, ...FlatNamespace[]] = DefaultNamespace,
+		KPrefix extends KeyPrefix<FallbackNs<N>> = undefined,
+	>(
 		locale: string,
 		namespaces?: N,
 		options?: Omit<InitOptions, "react"> & { keyPrefix?: KPrefix },
-	): Promise<TFunction<N, KPrefix>>;
-	async getFixedT<N extends Namespace, KPrefix extends string = "">(
+	): Promise<TFunction<FallbackNs<N>, KPrefix>>;
+	async getFixedT<
+		N extends
+			| FlatNamespace
+			| readonly [FlatNamespace, ...FlatNamespace[]] = DefaultNamespace,
+		KPrefix extends KeyPrefix<FallbackNs<N>> = undefined,
+	>(
 		request: Request,
 		namespaces?: N,
 		options?: Omit<InitOptions, "react"> & { keyPrefix?: KPrefix },
-	): Promise<TFunction<N, KPrefix>>;
-	async getFixedT<N extends Namespace, KPrefix extends string = "">(
+	): Promise<TFunction<FallbackNs<N>, KPrefix>>;
+	async getFixedT<
+		N extends
+			| FlatNamespace
+			| readonly [FlatNamespace, ...FlatNamespace[]] = DefaultNamespace,
+		KPrefix extends KeyPrefix<FallbackNs<N>> = undefined,
+	>(
 		requestOrLocale: Request | string,
 		namespaces?: N,
 		options: Omit<InitOptions, "react"> & { keyPrefix?: KPrefix } = {},
-	): Promise<TFunction<N, KPrefix>> {
-		let parsedNamespaces = namespaces ?? DEFAULT_NS;
-		// Make sure there's at least one namespace
-		if (!namespaces || namespaces.length === 0) {
-			parsedNamespaces = (this.options.i18next?.defaultNS ||
-				"translation") as N;
-		}
-
+	): Promise<TFunction<FallbackNs<N>, KPrefix>> {
 		let [instance, locale] = await Promise.all([
-			this.createInstance({
-				...this.options.i18next,
-				...options,
-				fallbackNS: parsedNamespaces,
-				defaultNS:
-					typeof parsedNamespaces === "string"
-						? parsedNamespaces
-						: parsedNamespaces[0],
-			}),
+			this.createInstance({ ...this.options.i18next, ...options }),
 			typeof requestOrLocale === "string"
 				? requestOrLocale
 				: this.getLocale(requestOrLocale),
 		]);
 
 		await instance.changeLanguage(locale);
-		await instance.loadNamespaces(parsedNamespaces);
 
-		return instance.getFixedT(locale, parsedNamespaces, options?.keyPrefix);
+		if (namespaces) await instance.loadNamespaces(namespaces);
+		else if (instance.options.defaultNS) {
+			await instance.loadNamespaces(instance.options.defaultNS);
+		} else await instance.loadNamespaces("translation" as DefaultNamespace);
+
+		return instance.getFixedT<N, KPrefix, N>(
+			locale,
+			namespaces,
+			options?.keyPrefix,
+		);
 	}
 
 	private async createInstance(options: Omit<InitOptions, "react"> = {}) {