如何使用IEnumerable模拟List<> [英] How do I use the IEnumerable to emulate a List<>

问题描述

在这种情况下，我对IEnumerable有点困惑。它是否准确描述了List< Class1>？



错误在foreach语句中只有foreach是红色下划线而不是item或者模型。

错误代码：

I am a little confused about the IEnumerable in this case. Does it accurately depict List<Class1>?

The error is in the "foreach" statement only the "foreach" is red underlined but not the "item" or the "Model".
Error Code:

foreach statement cannot operate on variables of type 'System.Collections.Generic.IEnumerator<SimpleMVC5.Models.Class1>' because 'System.Collections.Generic.IEnumerator<SimpleMVC5.Models.Class1>' does not contain a public definition for 'GetEnumerator'   c:\Users\Optiplex760\Documents\a  ASP.net 4.5\csharp\a MVC\SimpleMVC5\SimpleMVC5\Views\Home\Index.cshtml

Index.cshtml

Index.cshtml

@model IEnumerable<SimpleMVC5.Models.Class1>
        <table>
            @foreach (var item in Model)
            {
                <tr>
                    <td>@item.idt</td>
                    <td>@item.datetime0</td>
                    <td>@item.col1</td>
                    <td>@item.col2</td>
                    <td>@item.col3</td>
                </tr>
            }
        </table>

HomeController.cs

HomeController.cs

public class HomeController : Controller
    {
        private testContext db = new testContext();
        List<Class1> lst = new List<Class1>();
        public ActionResult Index()
        {
            lst = db.Data1.ToList();
            return View(lst);
        }

Class1.cs

Class1.cs

public class Class1
    {
        public int idt { get; set; }
        public string datetime0 { get; set; }
        public string col1 { get; set; }
        public string col2 { get; set; }
        public string col3 { get; set; }
    }
    public class testContext : DbContext
    {
        public DbSet<Class1> Data1 { get; set; }
    }

web.config

web.config

<connectionStrings>
    <add name="testContext" connectionString="Data Source=(LocalDb)\v11.0;AttachDbFilename=|DataDirectory|\SimpleMVC5db.mdf;Integrated Security=True"

      providerName="System.Data.SqlClient" />
</connectionStrings>

和SimpleMVC5d​​b.mdf已定义并填充数据。



如果我在lst = db.Data1.ToList（）;行调试它。错误代码：

And SimpleMVC5db.mdf is defined and is populated with data.

If I debug it on line "lst = db.Data1.ToList();". Error code:

An exception of type 'System.Data.Entity.ModelConfiguration.ModelValidationException' occurred in EntityFramework.dll but was not handled in user code

Additional information: One or more validation errors were detected during model generation:

推荐答案

Class1 没有定义键。密钥按惯例，属性或流畅的api标识：创建使用实体框架代码的主键首先 [ ^ ]



尝试：

Class1 has no key defined. Keys are either identified by convention, by attribute or fluent api: Create Primary Key using Entity Framework Code First[^]

Try:

public class Class1
    {
        [Key]
        public int idt { get; set; }
        public string datetime0 { get; set; }
        public string col1 { get; set; }
        public string col2 { get; set; }
        public string col3 { get; set; }
    }

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