无法将类型“System.Collections.Generic.List<anonymous type:string ClassID,string ClsssName>”隐式转换为“System.Collections.Generic.List<Ecology.Model.EnergyFlowGraph>”
一、EF应用中,常见类型转换问题解决方案
public List<EnergyFlowGraph> GetData() { var data = db.EnergyFlowGraph.Select(d => new { ClassID = d.ClassID, ParentClassID = d.ParentClassID, ClassName = d.ClassName, }).ToList(); return data; //报错: 无法将类型“System.Collections.Generic.List<anonymous type:string ClassID,string ClsssName>”隐式转换为“System.Collections.Generic.List<Ecology.Model.EnergyFlowGraph>” // 根据提示可知错误的原因 匿名类型anonymous type //d => new EnergyFlowGraph //解决方案一: new EnergyFlowGraph //var data = db.EnergyFlowGraph.Select(d => new EnergyFlowGraph //{ // ClassID = d.ClassID, // ParentClassID = d.ParentClassID, // ClassName = d.ClassName, //}).ToList(); //return data; //解决方案二:foreach遍历 //var list = new List<EnergyFlowGraph>(); //foreach (var temp in data) //{ // var energyFlowGraph = new EnergyFlowGraph(); // energyFlowGraph.ClassID = temp.ClassID; // energyFlowGraph.ClassName = temp.ClassName; // energyFlowGraph.ParentClassID = temp.ParentClassID; // list.Add(energyFlowGraph); //} //return list; }
二、model类
namespace Ecology.Models { using System; using System.Collections.Generic; public partial class EnergyFlowGraph { public string ClassID { get; set; } public string ParentClassID { get; set; } public string ClassName { get; set; } } }
三、测试结果
1、 经测,方案一失败,方案二成功。
2、有些情况下我们会专门为视图View(MVC)建一个视图类,已整合我们想要的数据。一般名称会区别于原始类名称。