Make Polls Anonymous (#1197)

* make polls anonymous

Introduce a `PollBlindVote` DB table that tracks when a user votes in a poll,
but does not track which choice they made.

Alter the `PollVote` DB table to remove the `userId` column, meaning `PollVote`
now tracks poll votes anonymously - it captures votes per poll option,
but does not track which user submitted the vote.

Update the `poll_vote` DB function to work with both tables now.

Update the `item.poll` resolver to calculate `meVoted` based on the `PollBlindVote`
table instead of `PollVote`.

* remove `meVoted` on `PollOption`s

---------

Co-authored-by: Keyan <34140557+huumn@users.noreply.github.com>

api/resolvers/item.js

@@ -1004,8 +1004,7 @@ export default {
       }
 
       const options = await models.$queryRaw`
-        SELECT "PollOption".id, option, count("PollVote"."userId")::INTEGER as count,
+        SELECT "PollOption".id, option, count("PollVote".id)::INTEGER as count
-          coalesce(bool_or("PollVote"."userId" = ${me?.id}), 'f') as "meVoted"
         FROM "PollOption"
         LEFT JOIN "PollVote" on "PollVote"."pollOptionId" = "PollOption".id
         WHERE "PollOption"."itemId" = ${item.id}
@@ -1013,9 +1012,16 @@ export default {
         ORDER BY "PollOption".id ASC
       `
 
+      const meVoted = await models.pollBlindVote.findFirst({
+        where: {
+          userId: me?.id,
+          itemId: item.id
+        }
+      })
+
       const poll = {}
       poll.options = options
-      poll.meVoted = options.some(o => o.meVoted)
+      poll.meVoted = !!meVoted
       poll.count = options.reduce((t, o) => t + o.count, 0)
 
       return poll

api/typeDefs/item.js

@@ -46,7 +46,6 @@ export default gql`
     id: ID,
     option: String!
     count: Int!
-    meVoted: Boolean!
   }
 
   type Poll {

components/poll.js

@@ -4,7 +4,6 @@ import { fixedDecimal, numWithUnits } from '@/lib/format'
 import { timeLeft } from '@/lib/time'
 import { useMe } from './me'
 import styles from './poll.module.css'
-import Check from '@/svgs/checkbox-circle-fill.svg'
 import { signIn } from 'next-auth/react'
 import ActionTooltip from './action-tooltip'
 import { POLL_COST } from '@/lib/constants'
@@ -40,9 +39,6 @@ export default function Poll ({ item }) {
       fields: {
         count (existingCount) {
           return existingCount + 1
-        },
-        meVoted () {
-          return true
         }
       }
     })
@@ -121,7 +117,7 @@ export default function Poll ({ item }) {
 function PollResult ({ v, progress }) {
   return (
     <div className={styles.pollResult}>
-      <span className={styles.pollOption}>{v.option}{v.meVoted && <Check className='fill-grey ms-1 align-self-center flex-shrink-0' width={16} height={16} />}</span>
+      <span className={styles.pollOption}>{v.option}</span>
       <span className='ms-auto me-2 align-self-center'>{progress}%</span>
       <div className={styles.pollProgress} style={{ width: `${progress}%` }} />
     </div>

fragments/items.js

@@ -126,7 +126,6 @@ export const POLL_FIELDS = gql`
         id
         option
         count
-        meVoted
       }
     }
   }`

prisma/migrations/20240527175411_anon_poll_vote/migration.sql

@@ -0,0 +1,92 @@
+-- CreateTable
+CREATE TABLE "PollBlindVote" (
+    "id" SERIAL NOT NULL,
+    "created_at" TIMESTAMP(3) NOT NULL DEFAULT CURRENT_TIMESTAMP,
+    "updated_at" TIMESTAMP(3) NOT NULL DEFAULT CURRENT_TIMESTAMP,
+    "itemId" INTEGER NOT NULL,
+    "userId" INTEGER NOT NULL,
+
+    CONSTRAINT "PollBlindVote_pkey" PRIMARY KEY ("id")
+);
+
+-- CreateIndex
+CREATE INDEX "PollBlindVote.userId_index" ON "PollBlindVote"("userId");
+
+-- CreateIndex
+CREATE UNIQUE INDEX "PollBlindVote.itemId_userId_unique" ON "PollBlindVote"("itemId", "userId");
+
+-- AddForeignKey
+ALTER TABLE "PollBlindVote" ADD CONSTRAINT "PollBlindVote_itemId_fkey" FOREIGN KEY ("itemId") REFERENCES "Item"("id") ON DELETE CASCADE ON UPDATE CASCADE;
+
+-- AddForeignKey
+ALTER TABLE "PollBlindVote" ADD CONSTRAINT "PollBlindVote_userId_fkey" FOREIGN KEY ("userId") REFERENCES "users"("id") ON DELETE CASCADE ON UPDATE CASCADE;
+
+-- migrate existing poll votes
+INSERT INTO "PollBlindVote" ("itemId", "userId")
+  SELECT "itemId", "userId" FROM "PollVote";
+
+/*
+  Warnings:
+
+  - You are about to drop the column `userId` on the `PollVote` table. All the data in the column will be lost.
+
+*/
+-- DropForeignKey
+ALTER TABLE "PollVote" DROP CONSTRAINT "PollVote_userId_fkey";
+
+-- DropIndex
+DROP INDEX "PollVote.itemId_userId_unique";
+
+-- DropIndex
+DROP INDEX "PollVote.userId_index";
+
+-- AlterTable
+ALTER TABLE "PollVote" DROP COLUMN "userId";
+
+-- update `poll_vote` function to update both "PollVote" and "PollBlindVote" tables
+-- create poll vote
+-- if user hasn't already voted
+-- charges user item.pollCost
+-- adds POLL to ItemAct
+-- adds PollVote
+-- adds PollBlindVote
+CREATE OR REPLACE FUNCTION poll_vote(option_id INTEGER, user_id INTEGER)
+RETURNS "Item"
+LANGUAGE plpgsql
+AS $$
+DECLARE
+    item "Item";
+    option "PollOption";
+BEGIN
+    PERFORM ASSERT_SERIALIZED();
+
+    SELECT * INTO option FROM "PollOption" where id = option_id;
+    IF option IS NULL THEN
+        RAISE EXCEPTION 'INVALID_POLL_OPTION';
+    END IF;
+
+    SELECT * INTO item FROM "Item" where id = option."itemId";
+    IF item IS NULL THEN
+        RAISE EXCEPTION 'POLL_DOES_NOT_EXIST';
+    END IF;
+
+    IF item."userId" = user_id THEN
+        RAISE EXCEPTION 'POLL_OWNER_CANT_VOTE';
+    END IF;
+
+    -- no longer check `PollVote` to see if a user has voted. Instead, check `PollBlindVote`
+    IF EXISTS (SELECT 1 FROM "PollBlindVote" WHERE "itemId" = item.id AND "userId" = user_id) THEN
+        RAISE EXCEPTION 'POLL_VOTE_ALREADY_EXISTS';
+    END IF;
+
+    PERFORM item_act(item.id, user_id, 'POLL', item."pollCost");
+
+    INSERT INTO "PollVote" (created_at, updated_at, "itemId", "pollOptionId")
+        VALUES (now_utc(), now_utc(), item.id, option_id);
+
+    INSERT INTO "PollBlindVote" (created_at, updated_at, "itemId", "userId")
+        VALUES (now_utc(), now_utc(), item.id, user_id);
+
+    RETURN item;
+END;
+$$;

prisma/schema.prisma

@@ -80,7 +80,6 @@ model User {
   actions                   ItemAct[]
   mentions                  Mention[]
   messages                  Message[]
-  PollVote                  PollVote[]
   PushSubscriptions         PushSubscription[]
   ReferralAct               ReferralAct[]
   Streak                    Streak[]
@@ -126,6 +125,7 @@ model User {
   Replies                   Reply[]
   walletLogs                WalletLog[]
   Reminder                  Reminder[]
+  PollBlindVote             PollBlindVote[]
 
   @@index([photoId])
   @@index([createdAt], map: "users.created_at_index")
@@ -427,6 +427,7 @@ model Item {
   Ancestors          Reply[]               @relation("AncestorReplyItem")
   Replies            Reply[]
   Reminder           Reminder[]
+  PollBlindVote      PollBlindVote[]
 
   @@index([uploadId])
   @@index([lastZapAt])
@@ -504,16 +505,25 @@ model PollVote {
   id           Int        @id @default(autoincrement())
   createdAt    DateTime   @default(now()) @map("created_at")
   updatedAt    DateTime   @default(now()) @updatedAt @map("updated_at")
-  userId       Int
   itemId       Int
   pollOptionId Int
   item         Item       @relation(fields: [itemId], references: [id], onDelete: Cascade)
   pollOption   PollOption @relation(fields: [pollOptionId], references: [id], onDelete: Cascade)
-  user         User       @relation(fields: [userId], references: [id], onDelete: Cascade)
 
-  @@unique([itemId, userId], map: "PollVote.itemId_userId_unique")
   @@index([pollOptionId], map: "PollVote.pollOptionId_index")
-  @@index([userId], map: "PollVote.userId_index")
+}
+
+model PollBlindVote {
+  id        Int      @id @default(autoincrement())
+  createdAt DateTime @default(now()) @map("created_at")
+  updatedAt DateTime @default(now()) @updatedAt @map("updated_at")
+  itemId    Int
+  userId    Int
+  item      Item     @relation(fields: [itemId], references: [id], onDelete: Cascade)
+  user      User     @relation(fields: [userId], references: [id], onDelete: Cascade)
+
+  @@unique([itemId, userId], map: "PollBlindVote.itemId_userId_unique")
+  @@index([userId], map: "PollBlindVote.userId_index")
 }
 
 enum BillingType {