GridView排序状态保持

　　这几天一直在自测项目，发现一些细节问题，这里再记录一个GridView排序状态的问题。其实算不上问题，只是我自己以前没注意过这种情况，还是经验少。

　　GridView的Sorting方法在你点击某个Column的时候触发，而如果GridView支持分页，选择分页或者调整分页大小后，GridView会重新Bind，此时会变成默认的排序，不再是之前选中的某个栏位的排序规则。这里其实已经可以看出来了，就是GridView重新绑定的时候，没有获取到当前的排序规则，解决办法也很直观，就是把之前的排序规则保存起来，每次GridView执行Bind的时候，都加上排序规则。

　　上代码：

  #region GridView的排序
        ///<summary>
        /// GridView的排序
        ///</summary>
        ///<param name="sender"></param>
        ///<param name="e"></param>
        protected void gdvFiles_Sorting(object sender, GridViewSortEventArgs e)
        {
            try
            {
                //如果已经存了SortDirection，则已经有过排序
                if (ViewState["SortExpression"] != null && ViewState["SortDirection"] != null)
                {
                    DataPickerEvent.GridViewSorting(this.GetViewStateData<DataTable>("SourceTable" + DocTypeID), gdvFiles, e, GetViewStateData<string>("SortExpression"), GetViewStateData<string>("SortDirection"));
                }
                else
                {
                    DataPickerEvent.GridViewSorting(this.GetViewStateData<DataTable>("SourceTable" + DocTypeID), gdvFiles, e);
                }
                SetViewStateData("SortDirection", gdvFiles.Attributes["SortDirection"]);
                SetViewStateData("SortExpression", gdvFiles.Attributes["SortExpression"]);
            }
            catch (Exception ex)
            {
                string message = String.Format("SourceFrom gdvFiles_Sorting Error:" + ex.Message);
            }
        }
        #endregion

　　这个是GridView的Sorting方法，再看一下BindGridView的方法，就知道了：

    #region BindGridView
        ///<summary>
        /// 绑定GridView
        ///<param name="avaliable">是否显示UnAvaliable的记录</param>
        ///</summary>
        private void BindGridView(bool avaliable)
        {
            //获取维度信息
            List<DocAttributeEntity> attributeList = GetViewStateData<List<DocAttributeEntity>>("AttributeList" + DocTypeID);
            if (ViewState["SourceTable" + DocTypeID]!=null)
            {
                DynamicShow_gdvFiles(attributeList);
                DataTable dataSource = GetViewStateData<DataTable>("SourceTable" + DocTypeID);

                DataTable tableSource = dataSource.Clone();
                if (!avaliable)
                {
                    DataRow[] drs = dataSource.Select("File_Status='" + EnumDataHelper.GetEnumString<FileStatus>(FileStatus.Available) + "'");

                    foreach (DataRow dr in drs)
                    {
                        tableSource.ImportRow(dr);
                    }

                    if (tableSource.Rows.Count > 0)
                    {
                        DataView dv = tableSource.DefaultView;
                        if (ViewState["SortExpression"] != null && ViewState["SortDirection"] != null)
                        {
                            string strSortExpression = ViewState["SortExpression"].ToString();
                            string strSortDirection = ViewState["SortDirection"].ToString();
                            dv.Sort = strSortExpression + "" + strSortDirection;
                        }

                        this.gdvFiles.DataSource = dv;
                        this.gdvFiles.DataBind();
                        this.gdvFiles.Visible = true;
                        this.divNoSearchResult.Visible = false;
                    }
                    else
                    {
                        this.gdvFiles.Visible = false;
                        this.divNoSearchResult.Visible = true;
                    }
                }
                else
                {

                    if (dataSource.Rows.Count > 0)
                    {
                        DataView dv = tableSource.DefaultView;
                        if (ViewState["SortExpression"] != null && ViewState["SortDirection"] != null)
                        {
                            string strSortExpression = ViewState["SortExpression"].ToString();
                            string strSortDirection = ViewState["SortDirection"].ToString();
                            dv.Sort = strSortExpression + " " + strSortDirection;
                        }

                        　this.gdvFiles.DataSource = dv;

                        　　this.gdvFiles.DataBind();
                        this.gdvFiles.Visible = true;
                        this.divNoSearchResult.Visible = false;
                    }
                    else
                    {
                        this.gdvFiles.Visible = false;
                        this.divNoSearchResult.Visible = true;
                    }
                }
            }
        }
        #endregion