DevExpress ASP.NET 使用经验谈（4）-CriteriaOperator的使用

上一节中，我们已经介绍了，使用CriteriaOperator表达式，获取对象数据。

1 2	`CriteriaOperator criteria = CriteriaOperator.Parse("[UserID]='"` `+ obj.UserID +` `"'");` `Users objnew = session.FindObject<Users>(criteria);`

如果查询结果是多条数，我们可以使用XPCollection来接收：

XPCollection<Users> coll = new XPCollection<Users>(session);
CriteriaOperator criteria = CriteriaOperator.Parse("");
SortProperty sortProperty = new SortProperty("FirstName", SortingDirection.Ascending);
SortingCollection s = new SortingCollection(sortProperty);
coll.Session = session;
coll.Criteria = criteria;
coll.Sorting = s;

我们修改一下上节的例子，修改后的代码如下：

using System;
using System.Collections.Generic;
using System.Configuration;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using DevExpress.Data.Filtering;
using DevExpress.Xpo;
using DevExpress.Xpo.DB;
using XPOModel.DemoDB;
namespace DevConsole
{
    class Program
    {
        static void Main(string[] args)
        {
            string provider = ConfigurationManager.ConnectionStrings["ConnectionString"].ConnectionString;//获取数据库连接
            IDataLayer datalayer = new SimpleDataLayer(XpoDefault.GetConnectionProvider(provider, AutoCreateOption.DatabaseAndSchema));//建立数据层XPO独有的
            DevExpress.Xpo.Session session = new DevExpress.Xpo.Session(datalayer); //将数据层和会话绑定
 
            for (int i = 0; i < 10; i++)
            {
                Users obj = new Users(session);
                obj.FirstName = "Dave_" + i.ToString();
                obj.LastName = "Annable";
                obj.EmailID = "Admin@gmail.com";
                obj.Save();
            }
 
            XPCollection<Users> coll = new XPCollection<Users>(session);
            CriteriaOperator criteria = CriteriaOperator.Parse("");
            SortProperty sortProperty = new SortProperty("FirstName", SortingDirection.Ascending);
            SortingCollection s = new SortingCollection(sortProperty);
            coll.Session = session;
            coll.Criteria = criteria;
            coll.Sorting = s;
 
            for (int j = 0; j < coll.Count; j++)
            {
                Users obj = coll[j];
                Console.WriteLine(string.Format("ID：{0}，FirstName：{1},LastName：{2}", obj.UserID, obj.FirstName, obj.LastName));
            }
            Console.ReadLine();
        }
    }
}