我如何在C#中的属性来获取一个属性的名称(2.0) [英] How do I get the name of a property from a property in C# (2.0)
问题描述
我知道我可以有一个属性,但是这更多的工作比我想去......并没有足够一般。
I know I could have an attribute but that's more work than I want to go to... and not general enough.
我想要做这样的事情。
class Whotsit
{
private string testProp = "thingy";
public string TestProp
{
get { return testProp; }
set { testProp = value; }
}
}
...
Whotsit whotsit = new Whotsit();
string value = GetName(whotsit.TestProp); //precise syntax up for grabs..
在这里,我期望的值等于TestProp
where I'd expect value to equal "TestProp"
但我不能为我的生活找到合适的反射方法写的GetName方法...
but I can't for the life of me find the right reflection methods to write the GetName method...
编辑:为什么我要这么做?我有一个类来存储设置从名称,值表中读取。这是基于反射的通用方法填充。我很喜欢写反...
Why do I want to do this? I have a class to store settings read from a 'name', 'value' table. This is populated by a generalised method based upon reflection. I'd quite like to write the reverse...
/// <summary>
/// Populates an object from a datatable where the rows have columns called NameField and ValueField.
/// If the property with the 'name' exists, and is not read-only, it is populated from the
/// valueField. Any other columns in the dataTable are ignored. If there is no property called
/// nameField it is ignored. Any properties of the object not found in the data table retain their
/// original values.
/// </summary>
/// <typeparam name="T">Type of the object to be populated.</typeparam>
/// <param name="toBePopulated">The object to be populated</param>
/// <param name="dataTable">'name, 'value' Data table to populate the object from.</param>
/// <param name="nameField">Field name of the 'name' field'.</param>
/// <param name="valueField">Field name of the 'value' field.</param>
/// <param name="options">Setting to control conversions - e.g. nulls as empty strings.</param>
public static void PopulateFromNameValueDataTable<T>
(T toBePopulated, System.Data.DataTable dataTable, string nameField, string valueField, PopulateOptions options)
{
Type type = typeof(T);
bool nullStringsAsEmptyString = options == PopulateOptions.NullStringsAsEmptyString;
foreach (DataRow dataRow in dataTable.Rows)
{
string name = dataRow[nameField].ToString();
System.Reflection.PropertyInfo property = type.GetProperty(name);
object value = dataRow[valueField];
if (property != null)
{
Type propertyType = property.PropertyType;
if (nullStringsAsEmptyString && (propertyType == typeof(String)))
{
value = TypeHelper.EmptyStringIfNull(value);
}
else
{
value = TypeHelper.DefaultIfNull(value, propertyType);
}
property.SetValue(toBePopulated, System.Convert.ChangeType(value, propertyType), null);
}
}
}
进一步编辑:我只是在code,有Whotsit的实例,我想要得到的TestProp'属性的文本字符串。这似乎有点奇怪,我知道,我可以只使用文字TestProp - 或在我的课到的数据表功能的情况下,我会在PropertyInfos的foreach循环。我只是好奇...
FURTHER I am just in code, have an instance of Whotsit and I want to get the text string of the 'TestProp' property. It seems kind of weird I know, I can just use the literal "TestProp" - or in the case of my class to datatable function I'd be in a foreach loop of PropertyInfos. I was just curious...
原来的code的字符串常量,我发现笨拙。
The original code had string constants, which I found clumsy.
推荐答案
没有,没有什么可以做到这一点。这位前pression whotsit.TestProp
将评估的财产。你想要的是传说中的infoof操作符:
No, there's nothing to do this. The expression whotsit.TestProp
will evaluate the property. What you want is the mythical "infoof" operator:
// I wish...
MemberInfo member = infoof(whotsit.TestProp);
正因为如此,你只能使用反射来获取由名称的属性 - 从code没有。 (或者获得所有属性,当然,它仍然无法帮助你和你的样品虽然。)
As it is, you can only use reflection to get the property by name - not from code. (Or get all the properties, of course. It still doesn't help you with your sample though.)
一个替代方案是使用前pression树:
One alternative is to use an expression tree:
Expression<Func<string>> = () => whotsit.TestProp;
然后检查前pression树获取属性。
then examine the expression tree to get the property.
如果没有这种帮助,也许你可以详细了解你为什么要这个功能告诉我们什么?
If none of this helps, perhaps you could tell us more about why you want this functionality?
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