From e45df191df387a9f51891fbcb8c2e44211dc8e5e Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=E5=BC=80=E6=BA=90=E6=B5=B7=E5=93=A5?= <fuhai999@gmail.com>
Date: Mon, 22 May 2023 08:07:33 +0800
Subject: [PATCH] optimize paginate method

---
 .../java/com/mybatisflex/core/BaseMapper.java   | 17 ++++++++++++++++-
 .../com/mybatisflex/core/row/RowMapper.java     | 15 +++++++++++++++
 2 files changed, 31 insertions(+), 1 deletion(-)

diff --git a/mybatis-flex-core/src/main/java/com/mybatisflex/core/BaseMapper.java b/mybatis-flex-core/src/main/java/com/mybatisflex/core/BaseMapper.java
index 1548878b..d1297771 100644
--- a/mybatis-flex-core/src/main/java/com/mybatisflex/core/BaseMapper.java
+++ b/mybatis-flex-core/src/main/java/com/mybatisflex/core/BaseMapper.java
@@ -575,16 +575,25 @@ public interface BaseMapper<T> {
 
     default <R> Page<R> paginateAs(Page<R> page, QueryWrapper queryWrapper, Class<R> asType) {
         List<QueryColumn> selectColumns = CPI.getSelectColumns(queryWrapper);
+        List<QueryOrderBy> orderBys = CPI.getOrderBys(queryWrapper);
+
         List<Join> joins = CPI.getJoins(queryWrapper);
         boolean removedJoins = true;
-
         // 只有 totalRow 小于 0 的时候才会去查询总量
         // 这样方便用户做总数缓存，而非每次都要去查询总量
         // 一般的分页场景中，只有第一页的时候有必要去查询总量，第二页以后是不需要的
         if (page.getTotalRow() < 0) {
 
+            //移除 select
             CPI.setSelectColumns(queryWrapper, Collections.singletonList(count().as("total")));
 
+            //移除 OrderBy
+            if (CollectionUtil.isNotEmpty(orderBys)) {
+                CPI.setOrderBys(queryWrapper, null);
+            }
+
+
+            //移除 left join
             if (joins != null && !joins.isEmpty()) {
                 for (Join join : joins) {
                     if (!Join.TYPE_LEFT.equals(CPI.getJoinType(join))) {
@@ -615,6 +624,7 @@ public interface BaseMapper<T> {
                 CPI.setJoins(queryWrapper, null);
             }
 
+
             long count = selectCountByQuery(queryWrapper);
             page.setTotalRow(count);
         }
@@ -626,6 +636,11 @@ public interface BaseMapper<T> {
         //重置 selectColumns
         CPI.setSelectColumns(queryWrapper, selectColumns);
 
+        //重置 orderBys
+        if (CollectionUtil.isNotEmpty(orderBys)) {
+            CPI.setOrderBys(queryWrapper, orderBys);
+        }
+
         //重置 join
         if (removedJoins) {
             CPI.setJoins(queryWrapper, joins);
diff --git a/mybatis-flex-core/src/main/java/com/mybatisflex/core/row/RowMapper.java b/mybatis-flex-core/src/main/java/com/mybatisflex/core/row/RowMapper.java
index 78b2db76..ea85985f 100644
--- a/mybatis-flex-core/src/main/java/com/mybatisflex/core/row/RowMapper.java
+++ b/mybatis-flex-core/src/main/java/com/mybatisflex/core/row/RowMapper.java
@@ -404,6 +404,9 @@ public interface RowMapper {
         CPI.setFromIfNecessary(queryWrapper, tableName);
 
         List<QueryColumn> selectColumns = CPI.getSelectColumns(queryWrapper);
+
+        List<QueryOrderBy> orderBys = CPI.getOrderBys(queryWrapper);
+
         List<Join> joins = CPI.getJoins(queryWrapper);
         boolean removedJoins = true;
 
@@ -412,8 +415,15 @@ public interface RowMapper {
         // 一般的分页场景中，只有第一页的时候有必要去查询总量，第二页以后是不需要的
         if (page.getTotalRow() < 0) {
 
+            //移除 seelct
             CPI.setSelectColumns(queryWrapper, Collections.singletonList(count().as("total")));
 
+            //移除 OrderBy
+            if (CollectionUtil.isNotEmpty(orderBys)) {
+                CPI.setOrderBys(queryWrapper, null);
+            }
+
+            //移除 left join
             if (joins != null && !joins.isEmpty()) {
                 for (Join join : joins) {
                     if (!Join.TYPE_LEFT.equals(CPI.getJoinType(join))) {
@@ -455,6 +465,11 @@ public interface RowMapper {
         //重置 selectColumns
         CPI.setSelectColumns(queryWrapper, selectColumns);
 
+        //重置 orderBys
+        if (CollectionUtil.isNotEmpty(orderBys)) {
+            CPI.setOrderBys(queryWrapper, orderBys);
+        }
+
         //重置 join
         if (removedJoins) {
             CPI.setJoins(queryWrapper, joins);