修复日志列表取消字段排序时的报错问题

-package com.ruoyi.common.core.page;
-
-import com.ruoyi.common.utils.StringUtils;
-
-/**
- * 分页数据
- * 
- * @author ruoyi
- */
-public class PageDomain
-{
-    /** 当前记录起始索引 */
-    private Integer pageNum;
-
-    /** 每页显示记录数 */
-    private Integer pageSize;
-
-    /** 排序列 */
-    private String orderByColumn;
-
-    /** 排序的方向desc或者asc */
-    private String isAsc = "asc";
-
-    public String getOrderBy()
-    {
-        if (StringUtils.isEmpty(orderByColumn))
-        {
-            return "";
-        }
-        return StringUtils.toUnderScoreCase(orderByColumn) + " " + isAsc;
-    }
-
-    public Integer getPageNum()
-    {
-        return pageNum;
-    }
-
-    public void setPageNum(Integer pageNum)
-    {
-        this.pageNum = pageNum;
-    }
-
-    public Integer getPageSize()
-    {
-        return pageSize;
-    }
-
-    public void setPageSize(Integer pageSize)
-    {
-        this.pageSize = pageSize;
-    }
-
-    public String getOrderByColumn()
-    {
-        return orderByColumn;
-    }
-
-    public void setOrderByColumn(String orderByColumn)
-    {
-        this.orderByColumn = orderByColumn;
-    }
-
-    public String getIsAsc()
-    {
-        return isAsc;
-    }
-
-    public void setIsAsc(String isAsc)
-    {
-        // 兼容前端排序类型
-        if ("ascending".equals(isAsc))
-        {
-            isAsc = "asc";
-        }
-        else if ("descending".equals(isAsc))
-        {
-            isAsc = "desc";
-        }
-        this.isAsc = isAsc;
-    }
-}
+package com.ruoyi.common.core.page;
+
+import com.ruoyi.common.utils.StringUtils;
+
+/**
+ * 分页数据
+ * 
+ * @author ruoyi
+ */
+public class PageDomain
+{
+    /** 当前记录起始索引 */
+    private Integer pageNum;
+
+    /** 每页显示记录数 */
+    private Integer pageSize;
+
+    /** 排序列 */
+    private String orderByColumn;
+
+    /** 排序的方向desc或者asc */
+    private String isAsc = "asc";
+
+    public String getOrderBy()
+    {
+        if (StringUtils.isEmpty(orderByColumn))
+        {
+            return "";
+        }
+        return StringUtils.toUnderScoreCase(orderByColumn) + " " + isAsc;
+    }
+
+    public Integer getPageNum()
+    {
+        return pageNum;
+    }
+
+    public void setPageNum(Integer pageNum)
+    {
+        this.pageNum = pageNum;
+    }
+
+    public Integer getPageSize()
+    {
+        return pageSize;
+    }
+
+    public void setPageSize(Integer pageSize)
+    {
+        this.pageSize = pageSize;
+    }
+
+    public String getOrderByColumn()
+    {
+        return orderByColumn;
+    }
+
+    public void setOrderByColumn(String orderByColumn)
+    {
+        this.orderByColumn = orderByColumn;
+    }
+
+    public String getIsAsc()
+    {
+        return isAsc;
+    }
+
+    public void setIsAsc(String isAsc)
+    {
+        if (StringUtils.isNotEmpty(isAsc)) {
+            // 兼容前端排序类型
+            if ("ascending".equals(isAsc))
+            {
+                isAsc = "asc";
+            }
+            else if ("descending".equals(isAsc))
+            {
+                isAsc = "desc";
+            }
+            this.isAsc = isAsc;
+        }
+    }
+}