优化接口，实现分页查询

routes/user.js

@@ -65,12 +65,82 @@ router.get(
     }
 );
 
-// 获取所有聊天消息
+// 获取最近联系人的最后一条聊天消息
 router.get(
-    "/messagesInfo",
+    "/recentChats",
     authMiddleware,
     (req, res) => {    
         const currentUserName = req.user.username;     
+        const sql = `
+            SELECT
+                contact_name,
+                content,
+                created_at
+            FROM (
+                SELECT
+                    CASE
+                        WHEN sender_name = ? THEN receiver_name
+                        ELSE sender_name
+                    END AS contact_name,
+                    content,
+                    created_at,
+                    ROW_NUMBER() OVER (
+                        PARTITION BY
+                            CASE
+                                WHEN sender_name = ? THEN receiver_name
+                                ELSE sender_name
+                            END
+                        ORDER BY created_at DESC
+                    ) AS rn
+                FROM chat_mysql.messages
+                WHERE sender_name = ?
+                OR receiver_name = ?
+            ) t
+            WHERE rn = 1
+            ORDER BY created_at DESC;
+        `;
+        db.query(sql, [currentUserName, currentUserName, currentUserName, currentUserName], (error, results) => {
+            if (error) {
+                console.error("数据库查询失败：", error);
+
+                return res.status(500).json({
+                    code: 500,
+                    message: "查询失败",
+                });
+            }
+            if (results.length > 0) {
+                res.json({
+                    code: 200,
+                    message: "查询成功",
+                    data: {
+                        recentChats: results.map(message => ({
+                            contactName: message.contact_name,
+                            content: message.content,
+                            createdAt: message.created_at
+                        }))
+                    },
+                });
+            } else {
+                res.json({
+                    code: 401,
+                    message: "未找到联系人消息",
+                    data: {
+                        recentChats: []
+                    }
+                });
+            }
+        });
+
+    }
+);
+
+// 获取某个联系人的最近n条聊天消息，分页获取
+router.post(
+    "/contactMessagesInfo",
+    authMiddleware,
+    (req, res) => {    
+        const currentUserName = req.user.username;  
+        const { contactName, limit } = req.body;  
         const sql = `
             SELECT
                 id,
@@ -79,10 +149,10 @@ router.get(
                 content,
                 created_at
             FROM chat_mysql.messages
-            WHERE sender_name = ? OR receiver_name = ?
-            ORDER BY created_at ASC;
+            WHERE (sender_name = ? OR receiver_name = ?) AND (sender_name = ? OR receiver_name = ?)
+            ORDER BY created_at ASC LIMIT ? ;
         `;
-        db.query(sql, [currentUserName, currentUserName], (error, results) => {
+        db.query(sql, [currentUserName, currentUserName, contactName, contactName, limit], (error, results) => {
             if (error) {
                 console.error("数据库查询失败：", error);