C# 通过属性反射设置属性值
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C# setting property values through reflection with attributes
提问by johnc
I am trying to build an object through an attribute on a classes property that specifies a column in a supplied data row that is the value of the property, as below:
我正在尝试通过 classes 属性上的属性构建一个对象，该属性在提供的数据行中指定一列作为该属性的值，如下所示：
[StoredDataValue("guid")]
public string Guid { get; protected set; }
[StoredDataValue("PrograGuid")]
public string ProgramGuid { get; protected set; }
In a Build() method on a base object, I am getting the attribute values set on these properties as
在基础对象的 Build() 方法中，我将这些属性上设置的属性值设置为
MemberInfo info = GetType();
object[] properties = info.GetCustomAttributes(true);
However, at this point I am realising the limitation in my knowledge.
然而，在这一点上，我意识到我的知识有限。
For a start, I don't appear to be getting back the correct attributes.
首先，我似乎没有找回正确的属性。
And how do I set these properties through reflection, now that I have the attributes? Am I doing / thinking something fundamentally incorrect?
以及如何通过反射设置这些属性，现在我有了这些属性？我在做/思考一些根本不正确的事情吗？
采纳答案by Tamas Czinege
There are a couple of separate issues here
这里有几个单独的问题
typeof(MyClass).GetCustomAttributes(bool)(orGetType().GetCustomAttributes(bool)) returns the attributes on the class itself, not the attributes on members. You will have to invoketypeof(MyClass).GetProperties()to get a list of properties in the class, and then check each of them.Once you got the property, I think you should use
Attribute.GetCustomAttribute()instead ofMemberInfo.GetGustomAttributes()since you exactly know what attribute you are looking for.
typeof(MyClass).GetCustomAttributes(bool)(或GetType().GetCustomAttributes(bool)) 返回类本身的属性，而不是成员的属性。您必须调用typeof(MyClass).GetProperties()以获取类中的属性列表，然后检查每个属性。一旦你获得了属性，我认为你应该使用
Attribute.GetCustomAttribute()而不是MemberInfo.GetGustomAttributes()因为你确切地知道你正在寻找什么属性。
Here's a little code snippet to help you start:
这是一个小代码片段，可帮助您开始：
PropertyInfo[] properties = typeof(MyClass).GetProperties();
foreach(PropertyInfo property in properties)
{
StoredDataValueAttribute attribute =
Attribute.GetCustomAttribute(property, typeof(StoredDataValueAttribute)) as StoredDataValueAttribute;
if (attribute != null) // This property has a StoredDataValueAttribute
{
property.SetValue(instanceOfMyClass, attribute.DataValue, null); // null means no indexes
}
}
EDIT: Don't forget that Type.GetProperties()only returns public properties by default. You will have to use Type.GetProperties(BindingFlags)to get other sorts of properties as well.
编辑：不要忘记Type.GetProperties()默认情况下只返回公共属性。您还必须使用Type.GetProperties(BindingFlags)来获取其他类型的属性。
