feat: implement description metatag for transition page in a naive way

src/server/controllers/RedirectController.ts

@@ -1,5 +1,6 @@
 import Express from 'express'
 import { inject, injectable } from 'inversify'
+import { escape } from 'lodash'
 import { gaTrackingId, logger } from '../config'
 import { NotFoundError } from '../util/error'
 import parseDomain from '../util/domain'
@@ -68,10 +69,11 @@ export class RedirectController implements RedirectControllerInterface {
       return
     }
 
-    // Find longUrl to redirect to.
+    // Find longUrl to redirect to and description.
     try {
       const {
         longUrl,
+        description,
         visitedUrls,
         redirectType,
       } = await this.redirectService.redirectFor(
@@ -95,6 +97,9 @@ export class RedirectController implements RedirectControllerInterface {
         const rootDomain: string = parseDomain(longUrl)
 
         res.status(200).render(TRANSITION_PATH, {
+          metaTagDescription: RedirectController.renderMetaTagDescription(
+            description,
+          ),
           escapedLongUrl: RedirectController.encodeLongUrl(longUrl),
           rootDomain,
           gaTrackingId,
@@ -127,6 +132,14 @@ export class RedirectController implements RedirectControllerInterface {
   private static encodeLongUrl(longUrl: string) {
     return longUrl.replace(/["]/g, encodeURIComponent)
   }
+
+  private static renderMetaTagDescription(description: string | null) {
+    if (!description) {
+      return ''
+    }
+
+    return `<meta name="description" content="${escape(description)}" />`
+  }
 }
 
 export default RedirectController

src/server/repositories/UrlRepository.ts

@@ -134,6 +134,25 @@ export class UrlRepository implements UrlRepositoryInterface {
     }
   }
 
+  /**
+   * Retrieves the description of the short url from the database.
+   * @param  {string} shortUrl Short url.
+   * @returns The description of the short url.
+   */
+  public getDescription: (shortUrl: string) => Promise<string> = async (
+    shortUrl,
+  ) => {
+    const url = await Url.findOne({
+      where: { shortUrl, state: StorableUrlState.Active },
+    })
+    if (!url) {
+      throw new NotFoundError(
+        `shortUrl not found in database:\tshortUrl=${shortUrl}`,
+      )
+    }
+    return url.description
+  }
+
   public plainTextSearch: (
     query: string,
     order: SearchResultsSortOrder,

src/server/repositories/interfaces/UrlRepositoryInterface.ts

@@ -41,6 +41,14 @@ export interface UrlRepositoryInterface {
    */
   getLongUrl: (shortUrl: string) => Promise<string>
 
+  /**
+   * Looks up the description given a shortUrl from the database.
+   * @param {string} shortUrl The shortUrl.
+   * @returns Promise that resolves to the description.
+   * @throws {NotFoundError}
+   */
+  getDescription: (shortUrl: string) => Promise<string>
+
   /**
    * Performs plain text search on Urls based on their shortUrl and
    * description. The results are ranked in order of relevance based

src/server/services/RedirectService.ts

@@ -54,13 +54,16 @@ export class RedirectService implements RedirectServiceInterface {
 
     // Find longUrl to redirect to
     const longUrl = await this.urlRepository.getLongUrl(shortUrl)
+    // Find description of the shortUrl
+    const description = await this.urlRepository.getDescription(shortUrl)
 
     // Update clicks and click statistics in database.
     this.linkStatisticsService.updateLinkStatistics(shortUrl, userAgent)
 
     if (this.crawlerCheckService.isCrawler(userAgent)) {
       return {
         longUrl,
+        description,
         visitedUrls: pastVisits,
         redirectType: RedirectType.Direct,
       }
@@ -81,6 +84,7 @@ export class RedirectService implements RedirectServiceInterface {
 
     return {
       longUrl,
+      description,
       visitedUrls: newVisits,
       redirectType: renderTransitionPage
         ? RedirectType.TransitionPage

src/server/services/types.ts

@@ -9,6 +9,7 @@ export enum RedirectType {
 export type RedirectResult = {
   visitedUrls: string[]
   longUrl: string
+  description: string | null
   redirectType: RedirectType
 }
 

src/server/views/transition-page.ejs

@@ -3,6 +3,7 @@
 
 <head>
     <meta name="viewport" content="width=device-width, initial-scale=1.0, user-scalable=0">
+    <%- metaTagDescription %>
     <meta http-equiv="X-UA-Compatible" content="ie=edge">
     <meta http-equiv="Content-Language" content="en">
     <meta charset="UTF-8">