使用实体框架从动态/编程命名的列名中获取字段 [英] Get field from dynamically/programatically named column name with Entity Framework

问题描述

我正在寻找一种以动态/编程方式更改列和字段名称的方法；

I'm looking for a method to change column and field names dynamically/programatically;

作为:

string iLoadProfileValue = "ColumnName";

string lastCol = DatabaseFunctions.DatabaseClient
.tbl_MeterLoadProfile
.OrderByDescending(a => a.MeterReadDate)
.FirstOrDefault(a => a.MeterID == meterID).iLoadProfileValue;

我将以编程方式更改 iLoadProfileValue 的值.我想将该列的值设为 lastCol 变量.

I'll change iLoadProfileValue's value programatically. And I would like to get that column's value to lastCol variable.

怎么做?

非常感谢.

完成:

最后的情况是这样的:感谢 thepirat000 和 Dismissile

Last situation like this: THANKS to thepirat000 and Dismissile

string iLoadProfileValue = "MeterReadDate";
var myEntity = DatabaseFunctions.DatabaseClient.tbl_MeterLoadProfile.OrderByDescending(a => a.MeterReadDate).FirstOrDefault(a => a.MeterID == 6);

if (myEntity != null)
{
    var properties = myEntity.GetType().GetProperty(iLoadProfileValue);
    object value = properties.GetValue(myEntity);
}

推荐答案

您可以使用反射来获取属性列表.查看 System.Type 上的 GetProperties() 方法.

You could use reflection to get a list of properties. Look at the GetProperties() method on System.Type.

http://msdn.microsoft.com/en-us/library/aky14axb(v=vs.110).aspx

public PropertyInfo[] GetProperties()

然后您可以使用 LINQ 查找与您想要的属性匹配的属性:

You could then use LINQ to find a property that maches the one you want:

var myEntity = DatabaseFunctions.DatabaseClient
    .tbl_MeterLoadProfile
    .OrderByDescending(a => a.MeterReadDate)
    .FirstOrDefault(a => a.MeterID == meterID);

if(myEntity != null) {
    var properties = myEntity.GetType().GetProperties();

    // iterate through the list of public properties or query to find the one you want
    // for this example I will just get the first property, and use it to get the value:
    var firstProperty = properties.FirstOrDefault();

    // get the value, it will be an object so you might need to cast it
    object value = firstProperty.GetValue(myEntity);
}

正如 thepirat000 在评论中指出的那样，如果您只关心单个属性，您可以调用方法 GetProperty(string name) 而不是 GetProperties().如果您只关心一个属性，而不是反映实体中的所有列，这可能会更有效.

As thepirat000 pointed out in the comments, if you only care about a single property you can call the method GetProperty(string name) instead of GetProperties(). This would probably be more efficient if you only care about one property, and you are not reflecting over all columns in your entity.

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