Added file "backend/src/resolvers/follow.js"

WIP !!! In development! Not able to run now!

backend/src/resolvers/follow.js

@@ -0,0 +1,49 @@
+export default {
+    Mutation: {
+      follow: async (_object, params, context, _resolveInfo) => {
+        const { followedId, followedType } = params
+        const session = context.driver.session()
+  
+        let sessionRes = await session.run(
+          `MATCH (n {id: $id}), (u:User {id: $cypherParams.currentUserId})
+           WHERE $type IN labels(n) AND NOT $id = $cypherParams.currentUserId
+           MERGE (u)-[r:FOLLOWS]->(n)
+           RETURN COUNT(r) > 0`,
+          {
+            badgeId: fromBadgeId,
+            rewardedUserId: toUserId
+          }
+        )
+  
+        const [rewardedUser] = sessionRes.records.map(record => {
+          return record.get('rewardedUser')
+        })
+  
+        session.close()
+  
+        return rewardedUser.id
+      },
+  
+      unfollow: async (_object, params, context, _resolveInfo) => {
+        const { fromBadgeId, toUserId } = params
+        const session = context.driver.session()
+  
+        let sessionRes = await session.run(
+          `MATCH (badge:Badge {id: $badgeId})-[reward:REWARDED]->(rewardedUser:User {id: $rewardedUserId})
+          DELETE reward
+          RETURN rewardedUser {.id}`,
+          {
+            badgeId: fromBadgeId,
+            rewardedUserId: toUserId
+          }
+        )
+        const [rewardedUser] = sessionRes.records.map(record => {
+          return record.get('rewardedUser')
+        })
+        session.close()
+  
+        return rewardedUser.id
+      }
+    }
+  }
+