From 2021ab8b5cdb975c8a982fcd54cf45c01db796df Mon Sep 17 00:00:00 2001
From: tanish35 <tanishmajumdar2912@gmail.com>
Date: Thu, 24 Oct 2024 22:31:34 +0530
Subject: [PATCH] Remove cache upon new post

---
 backend/src/controllers/postController.ts | 12 +++++++---
 backend/src/lib/redis.ts                  | 28 +++++++++++++++++++++++
 2 files changed, 37 insertions(+), 3 deletions(-)

diff --git a/backend/src/controllers/postController.ts b/backend/src/controllers/postController.ts
index 7528edb..4b37646 100644
--- a/backend/src/controllers/postController.ts
+++ b/backend/src/controllers/postController.ts
@@ -4,7 +4,7 @@ import prisma from "../lib/prisma";
 import Fuse from "fuse.js";
 import sendMail from "../mail/sendMail";
 import { htmlToText } from "html-to-text";
-import { setCachedData, getCachedData } from "../lib/redis";
+import { setCachedData, getCachedData, deleteCachedPosts } from "../lib/redis";
 
 // @ts-ignore
 const searchPosts = asyncHandler(async (req: Request, res: Response) => {
@@ -38,7 +38,7 @@ const searchPosts = asyncHandler(async (req: Request, res: Response) => {
     },
   });
 
-  const plainTextPosts = posts.map((post : any) => ({
+  const plainTextPosts = posts.map((post: any) => ({
     ...post,
     content: htmlToText(post.content, {
       wordwrap: false,
@@ -124,7 +124,7 @@ const createPost = asyncHandler(async (req: Request, res: Response, next) => {
       college_id: collegeId,
     },
   });
-
+  await deleteCachedPosts(collegeId);
   return res.status(201).json({ post });
 });
 
@@ -286,6 +286,11 @@ const deletePost = asyncHandler(async (req: Request, res: Response) => {
           user_id: true,
         },
       },
+      College: {
+        select: {
+          college_id: true,
+        },
+      },
     },
     where: { post_id: postId },
   });
@@ -313,6 +318,7 @@ const deletePost = asyncHandler(async (req: Request, res: Response) => {
       where: { post_id: postId },
     });
   });
+  await deleteCachedPosts(post.College.college_id);
 
   return res.status(200).json({ message: "Post and comments deleted" });
 });
diff --git a/backend/src/lib/redis.ts b/backend/src/lib/redis.ts
index 28f0c9f..955488a 100644
--- a/backend/src/lib/redis.ts
+++ b/backend/src/lib/redis.ts
@@ -36,4 +36,32 @@ export const disconnectRedis = async (): Promise<void> => {
   }
 };
 
+export const deleteCachedPosts = async (collegeId: string): Promise<void> => {
+  try {
+    const collegePattern = `posts:${collegeId}:page:*`;
+    const allPattern = `posts:all:page:*`;
+    const collegeStream = redis.scanStream({ match: collegePattern });
+    const allStream = redis.scanStream({ match: allPattern });
+    collegeStream.on("data", (keys) => {
+      if (keys.length) {
+        redis.del(...keys);
+      }
+    });
+    allStream.on("data", (keys) => {
+      if (keys.length) {
+        redis.del(...keys);
+      }
+    });
+    collegeStream.on("end", () => {
+      console.log(`Deleted cache for collegeId: ${collegeId}`);
+    });
+
+    allStream.on("end", () => {
+      console.log(`Deleted all cache entries.`);
+    });
+  } catch (error) {
+    console.error("Error deleting cached posts from Redis", error);
+  }
+};
+
 export default redis;