C＃通过与反射属性设置属性值 [英] C# setting property values through reflection with attributes

问题描述

我试图通过指定所提供的数据行一列，它是该属性的值，如下一类属性的属性建立一个对​​象：

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:

    [StoredDataValue("guid")]
    public string Guid { get; protected set; }

    [StoredDataValue("PrograGuid")]
    public string ProgramGuid { get; protected set; }

在一个基础对象建立（）方法中，我得到的属性值设置这些属性

In a Build() method on a base object, I am getting the attribute values set on these properties as

        MemberInfo info = GetType();
        object[] properties = info.GetCustomAttributes(true);

不过，在这一点上，我意识到在我的知识的局限性。

However, at this point I am realising the limitation in my knowledge.

一开始，我似乎并没有被找回正确的属性。

For a start, I don't appear to be getting back the correct attributes.

和如何设置通过反思这些属性，现在我有属性？我做/想的东西根本不正确？

And how do I set these properties through reflection, now that I have the attributes? Am I doing / thinking something fundamentally incorrect?

推荐答案

有一对夫妇在这里不同的问题。

There are a couple of separate issues here

• 的typeof（MyClass的）.GetCustomAttributes（布尔）（或的GetType（） .GetCustomAttributes（布尔））返回类本身，而不是成员的属性的属性。你将不得不调用的typeof（MyClass的）.GetProperties（）来得到在类属性的列表，然后检查他们每个人。

• typeof(MyClass).GetCustomAttributes(bool) (or GetType().GetCustomAttributes(bool)) returns the attributes on the class itself, not the attributes on members. You will have to invoke typeof(MyClass).GetProperties() to get a list of properties in the class, and then check each of them.

一旦你得到的财产，我认为你应该使用 Attribute.GetCustomAttribute（）而不是的MemberInfo。 GetGustomAttributes（），因为你确切地知道什么属性，你所寻找的。

Once you got the property, I think you should use Attribute.GetCustomAttribute() instead of MemberInfo.GetGustomAttributes() since you exactly know what attribute you are looking for.

下面是一个小的代码片段，以帮助您开始：

Here's a little code snippet to help you start:

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
    }
}

修改：别忘了 Type.GetProperties（）默认情况下只返回公共属性。你将不得不使用 Type.GetProperties（的BindingFlags）来获得其他种类的属性以及

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.

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