把发消息写入数据库的时间都交给数据库来创建

websocket/index.js

@@ -129,21 +129,21 @@ function handleSendMessage(data, ws) {
     `${senderName} → ${receiverName}：${content}`
   );
 
-  const sql = `
+  const insertSql = `
     INSERT INTO messages
     (message_id, sender_name, receiver_name, content)
     VALUES (?, ?, ?, ?)
   `;
-  db.query(sql, [
+  db.query(insertSql, [
     messageId,
     senderName,
     receiverName,
     content
   ], (error, result) => {
+    const senderWs = getConnection(senderName);
     if (error) {
       console.error(error);
 
-      const senderWs = getConnection(senderName);
       if (senderWs) {
         senderWs.send(
           JSON.stringify({
@@ -156,17 +156,60 @@ function handleSendMessage(data, ws) {
       return;
     }
 
-    // 数据库确认写入后，才确认发送并推送给接收者
-    const senderWs = getConnection(senderName);
+    // 插入新消息之后，用messageID查询这条新消息的时间点（为了使用数据库插入时创建的时间点，不能用前端自己生成的）
+    const timeSql = `
+      SELECT created_at
+      FROM messages
+      WHERE message_id = ?
+    `;
+    db.query(timeSql, [messageId], (error, results) => {
+      if (error) {
+        console.error("查询消息失败：", error);
+
+        if (senderWs) {
+          senderWs.send(
+            JSON.stringify({
+              type: "sendError",
+              messageId: messageId,
+              message: "获取消息失败"
+            })
+          );
+        }
+        return;
+      }
+
+      if (results.length === 0) {
+        if (senderWs) {
+          senderWs.send(
+            JSON.stringify({
+              type: "sendError",
+              messageId: messageId,
+              message: "获取消息失败"
+            })
+          );
+        }
+        return;
+      }
+
+      const createdAt = results[0].created_at;
+
+      // 数据库确认写入后，才把成功写入的消息推送给发送者
       if (senderWs) {
         senderWs.send(
           JSON.stringify({
             type: "sendSuccess",
-          messageId: messageId
+            message: {
+              messageId,
+              senderName,
+              receiverName,
+              content,
+              createdAt
+            }
           })
         );
       }
 
+      // 把写入的新消息推送给接收者，如果接收者不在线，就不用发送websocket消息给他了，但数据库里是有的
       const receiverWs = getConnection(receiverName);
       if (!receiverWs) {
         console.log(`${receiverName} 当前不在线`);
@@ -180,11 +223,13 @@ function handleSendMessage(data, ws) {
             messageId,
             senderName,
             receiverName,
-          content
+            content,
+            createdAt
           },
         })
       );
     });
+  });
 }
 
 function handleAck(data, ws) {