Increment follower count as well

functions/src/follow-market.ts

@@ -1,5 +1,4 @@
 import * as admin from 'firebase-admin'
-import { FieldValue } from 'firebase-admin/firestore'
 
 const firestore = admin.firestore()
 
@@ -19,12 +18,6 @@ export const addUserToContractFollowers = async (
       id: userId,
       createdTime: Date.now(),
     })
-  await firestore
-    .collection(`contracts`)
-    .doc(contractId)
-    .update({
-      followerCount: FieldValue.increment(1),
-    })
 }
 
 export const removeUserFromContractFollowers = async (
@@ -40,10 +33,4 @@ export const removeUserFromContractFollowers = async (
     .collection(`contracts/${contractId}/follows`)
     .doc(userId)
     .delete()
-  await firestore
-    .collection(`contracts`)
-    .doc(contractId)
-    .update({
-      followerCount: FieldValue.increment(-1),
-    })
 }

functions/src/index.ts

@@ -30,7 +30,7 @@ export * from './score-contracts'
 export * from './weekly-markets-emails'
 export * from './reset-betting-streaks'
 export * from './reset-weekly-emails-flag'
-export * from './on-delete-contract-follow'
+export * from './on-update-contract-follow'
 
 // v2
 export * from './health'

functions/src/on-update-contract-follow.ts

@@ -22,3 +22,24 @@ export const onDeleteContractFollow = functions.firestore
         followerCount: FieldValue.increment(-1),
       })
   })
+
+export const onCreateContractFollow = functions.firestore
+  .document('contracts/{contractId}/follows/{userId}')
+  .onCreate(async (change, context) => {
+    const { contractId } = context.params as {
+      contractId: string
+    }
+    const firestore = admin.firestore()
+    const contract = await firestore
+      .collection(`contracts`)
+      .doc(contractId)
+      .get()
+    if (!contract.exists) throw new Error('Could not find contract')
+
+    await firestore
+      .collection(`contracts`)
+      .doc(contractId)
+      .update({
+        followerCount: FieldValue.increment(1),
+      })
+  })

functions/src/scripts/backfill-contract-followers.ts

@@ -55,11 +55,12 @@ async function backfillContractFollowers() {
         .doc(followerId)
         .set({ id: followerId, createdTime: Date.now() })
     }
-    const followerCount = followerIds.length
-    await firestore
-      .collection(`contracts`)
-      .doc(contract.id)
-      .update({ followerCount: followerCount })
+    // Perhaps handled by the trigger?
+    // const followerCount = followerIds.length
+    // await firestore
+    //   .collection(`contracts`)
+    //   .doc(contract.id)
+    //   .update({ followerCount: followerCount })
     count += 1
     if (count % 100 === 0) {
       console.log(`${count} contracts processed`)