Merge pull request #2023 from kaioduarte/perf/lazy-load-swagger-ui

perf(swagger-module): lazy load swagger-ui-dist module
nestjs · Sep 1, 2022 · 1dc851c · 1dc851c
2 parents 69df9c8 + 857a2d8
commit 1dc851c
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Showing 2 changed files with 15 additions and 4 deletions.
diff --git a/lib/swagger-module.ts b/lib/swagger-module.ts
@@ -12,7 +12,7 @@ import { SwaggerScanner } from './swagger-scanner';
 import {
   buildSwaggerHTML,
   buildSwaggerInitJS,
-  swaggerAssetsAbsoluteFSPath
+  getSwaggerAssetsAbsoluteFSPath
 } from './swagger-ui';
 import { assignTwoLevelsDeep } from './utils/assign-two-levels-deep';
 import { getGlobalPrefix } from './utils/get-global-prefix';
@@ -44,6 +44,7 @@ export class SwaggerModule {
 
   private static serveStatic(finalPath: string, app: INestApplication) {
     const httpAdapter = app.getHttpAdapter();
+    const swaggerAssetsAbsoluteFSPath = getSwaggerAssetsAbsoluteFSPath();
 
     if (httpAdapter && httpAdapter.getType() === 'fastify') {
       (app as NestFastifyApplication).useStaticAssets({

diff --git a/lib/swagger-ui/swagger-ui.ts b/lib/swagger-ui/swagger-ui.ts
@@ -1,4 +1,3 @@
-import * as swaggerUi from 'swagger-ui-dist';
 import { favIconHtml, htmlTemplateString, jsTemplateString } from './constants';
 import { OpenAPIObject, SwaggerCustomOptions } from '../interfaces';
 import { buildJSInitOptions } from './helpers';
@@ -21,10 +20,21 @@ export function buildSwaggerInitJS(
   return jsTemplateString.replace('<% swaggerOptions %>', jsInitOptions);
 }
 
+let swaggerAssetsAbsoluteFSPath: string | undefined;
+
 /**
- * Stores absolute path to swagger-ui assets
+ * Returns the absolute path to swagger-ui assets.
  */
-export const swaggerAssetsAbsoluteFSPath = swaggerUi.getAbsoluteFSPath();
+export function getSwaggerAssetsAbsoluteFSPath() {
+  if (!swaggerAssetsAbsoluteFSPath) {
+    // eslint-disable-next-line @typescript-eslint/no-var-requires
+    const swaggerUi = require('swagger-ui-dist');
+    swaggerAssetsAbsoluteFSPath = swaggerUi.getAbsoluteFSPath();
+  }
+
+  return swaggerAssetsAbsoluteFSPath;
+}
+
 /**
  * Used to build swagger-ui custom html
  */