[Add] 서버쪽 feed pubsub구현 #140

why
새로운 글을 등록하면 구독자들에게 알려주고, 구독자들은 그 알람을 받아야 함

how
graphql의 pubsub을 활용해서 새로 등록된 글에 대한 알람이 오늘 것을 확인

주의
서버쪽 구현이며 아직 필터링은 되지 않음

server/src/api/feed/feed.graphql

@@ -72,3 +72,7 @@ type Mutation {
 type Mutation {
   enrollFeed(content: String!, files: [Upload]): Boolean!
 }
+
+type Subscription {
+  newFeed: [IFeed]
+}

server/src/api/feed/feed.resolvers.ts

@@ -1,5 +1,10 @@
 import db from '../../db';
-import { MATCH_FEEDS, UPDATE_LIKE, DELETE_LIKE } from '../../schema/feed/query';
+import {
+  MATCH_FEEDS,
+  UPDATE_LIKE,
+  DELETE_LIKE,
+  GET_NEW_FEED
+} from '../../schema/feed/query';
 import { ParseResultRecords } from '../../utils/parseData';
 import {
   MutationEnrollFeedArgs,
@@ -63,7 +68,7 @@ const mutationResolvers: MutationResolvers = {
   enrollFeed: async (
     _,
     { content, files }: MutationEnrollFeedArgs,
-    { req }
+    { req, pubsub }
   ): Promise<boolean> => {
     const { email } = req;
     if (!email) return false;
@@ -73,6 +78,18 @@ const mutationResolvers: MutationResolvers = {
     if (files && files.length) {
       createImages(feedId, files);
     }
+
+    const registerdFeed = await requestDB(GET_NEW_FEED, {
+      feedId,
+      useremail: email
+    });
+    // console.log('registerdFeed?? ', registerdFeed);
+    const parsedRegisterdFeed = ParseResultRecords(registerdFeed);
+    // console.log('parsedRegisterdFeed?? ', parsedRegisterdFeed);
+
+    pubsub.publish(NEW_FEED, {
+      newFeed: parsedRegisterdFeed
+    });
     return true;
   },
   updateLike: async (_, { feedId, count }, { req }) => {
@@ -112,7 +129,17 @@ const queryResolvers: QueryResolvers = {
   }
 };
 
+const NEW_FEED = 'NEW_FEED_PUBSUB';
+
 export default {
   Query: queryResolvers,
-  Mutation: mutationResolvers
+  Mutation: mutationResolvers,
+  Subscription: {
+    newFeed: {
+      subscribe: (_, __, { pubsub }) => {
+        console.log('subscripbed');
+        return pubsub.asyncIterator(NEW_FEED);
+      }
+    }
+  }
 };

server/src/app.ts

@@ -1,6 +1,6 @@
 import cookieParser from 'cookie-parser';
 import cors from 'cors';
-import { GraphQLServer } from 'graphql-yoga';
+import { GraphQLServer, PubSub } from 'graphql-yoga';
 import helmet from 'helmet';
 import logger from 'morgan';
 import config from './utils/config';
@@ -12,9 +12,14 @@ import setUserFromJWT from './middleware/setUserFromJWT';
 class App {
   public app: GraphQLServer;
   constructor() {
+    const pubsub = new PubSub();
     this.app = new GraphQLServer({
       schema,
-      context: ({ request, response }) => ({ req: request, res: response })
+      context: ({ request, response }) => ({
+        req: request,
+        res: response,
+        pubsub
+      })
     });
     this.middlewares();
   }

server/src/schema/feed/query.ts

@@ -1,14 +1,3 @@
-/* const MATCH_FEEDS1 = `MATCH (searchUser:User)-[:AUTHOR]->(feed:Feed)
-OPTIONAL MATCH (likeUser:User)-[:LIKE]->(feed)
-OPTIONAL MATCH (feed)-[:HAS]->(com:Comment)
-WITH searchUser, feed, COLLECT(DISTINCT likeUser) AS cp , COLLECT(com) as comments
-where feed.createdAt <  datetime({cursor})
-RETURN searchUser , feed,  ID(feed) as feedId , length(cp) AS totallikes,
-length(filter(x IN cp WHERE x.email= {useremail} )) AS hasLiked, comments
-order by feed.createdAt desc
-LIMIT {first} 
-`; */
-
 const MATCH_FEEDS = `MATCH (searchUser:User)-[:AUTHOR]->(feed:Feed)
 OPTIONAL MATCH (likeUser:User)-[like:LIKE]->(feed)
 OPTIONAL MATCH (feed)-[:HAS]->(com:Comment)
@@ -32,4 +21,15 @@ MATCH (u:User)-[r:LIKE]->(f:Feed)
 WHERE u.email = {useremail} AND ID(f) = {feedId}
 delete r`;
 
-export { MATCH_FEEDS, UPDATE_LIKE, DELETE_LIKE };
+const GET_NEW_FEED = `MATCH (searchUser:User)-[:AUTHOR]->(feed:Feed)
+OPTIONAL MATCH (likeUser:User)-[like:LIKE]->(feed)
+OPTIONAL MATCH (feed)-[:HAS]->(com:Comment)
+OPTIONAL MATCH (feed)<-[:HAS]-(img:Image)
+WITH searchUser, feed, COLLECT(DISTINCT likeUser) AS cp , COLLECT(com) as comments, COLLECT(DISTINCT img) as imgs
+where ID(feed) = {feedId}
+RETURN searchUser , feed,  ID(feed) as feedId , length(cp) AS totallikes, imgs as imglist,
+length(filter(x IN cp WHERE x.email= {useremail} )) AS hasLiked, comments
+order by feed.createdAt desc
+`;
+
+export { MATCH_FEEDS, UPDATE_LIKE, DELETE_LIKE, GET_NEW_FEED };

server/src/utils/parseData.ts

@@ -39,7 +39,10 @@ export const Datetransform = object => {
   }
   return returnobj;
 };
-
+/**
+ * 주의사항 : 결과가 여러개이면 result.records 한개이면 result를 record로 받아야 함
+ * @param records
+ */
 export const ParseResultRecords = records => {
   let result: any[] = [];
   for (const item of records) {