修复动态发布与互动问题

cloudfunctions/messageThread/index.js

@@ -3,6 +3,7 @@ const cloud = require('wx-server-sdk')
 cloud.init({ env: cloud.DYNAMIC_CURRENT_ENV })
 const db = cloud.database()
 const _ = db.command
+const SERVER_MESSAGE_LIMIT = 50
 
 function timeText(ts) {
   if (!ts) return ''
@@ -18,12 +19,30 @@ async function userToPeer(u) {
   return { id: u._id, name: u.nickname || '用户', avatarKey: u.avatarKey || 'gradient-avatar-1', avatarUrl: u.avatarUrl || '' }
 }
 
+function normalizeLimit(value) {
+  const limit = Number(value || SERVER_MESSAGE_LIMIT)
+  if (!Number.isFinite(limit)) return SERVER_MESSAGE_LIMIT
+  return Math.max(1, Math.min(Math.floor(limit), SERVER_MESSAGE_LIMIT))
+}
+
+function messageToClient(m, openid) {
+  return {
+    _id: m._id,
+    fromMe: m.fromOpenid === openid,
+    content: m.content,
+    type: m.type || 'text',
+    createdAt: m.createdAt,
+    timeText: timeText(m.createdAt)
+  }
+}
+
 exports.main = async event => {
   const { OPENID } = cloud.getWXContext()
   if (!OPENID) throw new Error('no openid in wx context')
 
   let convId = event.conversationId || ''
   let peer = null
+  const pageSize = normalizeLimit(event.pageSize || event.limit)
 
   // Open by target user — resolve peer and find an existing conversation.
   if (!convId && event.targetUserId) {
@@ -56,27 +75,32 @@ exports.main = async event => {
   }
 
   let messages = []
+  let nextCursor = ''
   if (convId) {
+    const query = { conversationId: convId }
+    const cursor = Number(event.cursor || 0)
+    if (Number.isFinite(cursor) && cursor > 0) query.createdAt = _.lt(cursor)
+
     const res = await db.collection('messages')
-      .where({ conversationId: convId })
+      .where(query)
       .orderBy('createdAt', 'desc')
-      .limit(50)
+      .limit(pageSize + 1)
       .get()
       .catch(() => ({ data: [] }))
-    messages = res.data.reverse().map(m => ({
-      _id: m._id,
-      fromMe: m.fromOpenid === OPENID,
-      content: m.content,
-      type: m.type || 'text',
-      createdAt: m.createdAt,
-      timeText: timeText(m.createdAt)
-    }))
+    const page = res.data.slice(0, pageSize)
+    messages = page.reverse().map(m => messageToClient(m, OPENID))
+    if (res.data.length > pageSize && messages[0]) {
+      nextCursor = String(messages[0].createdAt || '')
+    }
 
-    // Mark this conversation read for me.
-    await db.collection('conversations').doc(convId).update({
-      data: { unreadOpenids: _.pull(OPENID), [`unreadCounts.${OPENID}`]: 0 }
-    }).catch(() => {})
+    // Mark this conversation read for me only when the client asks for it.
+    // Silent polling and loading older history should not write the conversation.
+    if (event.markRead !== false) {
+      await db.collection('conversations').doc(convId).update({
+        data: { unreadOpenids: _.pull(OPENID), [`unreadCounts.${OPENID}`]: 0 }
+      }).catch(() => {})
+    }
   }
 
-  return { conversationId: convId, peer, messages }
+  return { conversationId: convId, peer, messages, nextCursor }
 }