LINQ to Entities-使用字符串名称寻址类属性 [英] LINQ to Entities - Addressing class properties with their string names

问题描述

我有一个Kendo网格，其中启用了服务器端筛选.要过滤的字段以字符串形式传递.例如，我要按"SampleId"进行过滤.现在，我需要编写一个LINQ to Entities查询，该查询可以使用强类型属性SampleId进行过滤.例如:

I have a Kendo grid that has serverside filtering turned on. The field to filter by is passed as a string. For example, I want to filter by "SampleId". Now, I need to write a LINQ to Entities query that can filter by using the strongly-typed property SampleId. For example:

    db.Cases.Where(x=>targetlist.Contains(x.SampleId))

其中targetlist是过滤器中的项目列表.

where targetlist is a list of items from the filter.

实际上，有没有一种方法可以编写查询，使"SampleId"可以直接转换为Case.SampleId?

So, in effect, is there a way to write a query such that "SampleId" can directly translate to Case.SampleId?

我尝试了反射，并使用了GetProperty和GetValue，而LINQ to Entities不喜欢它.

I have tried reflection and made use of the GetProperty and GetValue and LINQ to Entities does not like it.

任何建议将不胜感激！

编辑(由pid制作，原始海报srinaik2020):

EDIT (by pid for original poster srinaik2020):

@zaitsman:这是在下面的评论中发布的代码，并且是根据接受的答案实际解决问题的方法.

@zaitsman: this is the code posted in an comment further below and is the actual resolution of the problem, based on the accepted answer.

public static class MyExtensions
{
    public static string GetPropertyByName(this CaseV case1, string name)
    {
        var x = typeof (CaseV).GetProperty(name).GetValue(case1);

        if (x != null)
        {
            return x.ToString();
        } else {
            return "none";
        }
    }
}

推荐答案

您可以使用扩展方法并将其附加到类中.

You can use an extension method and attach it to the class.

该方法应使用反射从对象中检索属性.

That method should use reflection to retrieve the property from the object.

以下是指针:

• 扩展方法
• GetProperty()

• Extension methods
• GetProperty()

一旦工作，您将只想设置和/或获取属性的值. 上面的GetProperty()方法仅返回PropertyInfo对象. 要获取或设置值，您必须使用PropertyInfo的适当方法.

Once this is working, you'll want just to set and/or get the value of the property. The GetProperty() method above just returns the PropertyInfo object. To get or set the value you'll have to use the appropriate methods of PropertyInfo.

我不会公开PropertyInfo，因为它会破坏神奇.

I'd not expose the PropertyInfo because it would ruin the magic.

最好使用扩展方法，然后:

Better have to extension methods, then:

T GetPropertyByName<T>(string name);
SetPropertyByName<T>(string name, T value);

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