[英]Select properties with specific attribute value
我正在尋找一種方法來選擇具有特定自定義屬性和單個 LINQ 語句中的特定值的屬性。
我得到了具有我想要的屬性的屬性,但我不知道如何選擇它的特定值。
<AttributeUsage(AttributeTargets.Property)>
Public Class PropertyIsMailHeaderParamAttribute
Inherits System.Attribute
Public Property HeaderAttribute As String = Nothing
Public Property Type As ParamType = Nothing
Public Sub New()
End Sub
Public Sub New(ByVal headerAttribute As String, ByVal type As ParamType)
Me.HeaderAttribute = headerAttribute
Me.Type = type
End Sub
Public Enum ParamType
base = 1
open
closed
End Enum
End Class
private MsgData setBaseProperties(MimeMessage mailItem, string fileName)
{
var msgData = new MsgData();
Type type = msgData.GetType();
var props = from p in this.GetType().GetProperties()
let attr = p.GetCustomAttributes(typeof(Business.IT._21c.AddonFW.PropertyIsMailHeaderAttribute), true)
where attr.Length == 1
select new { Property = p, Attribute = attr.FirstOrDefault() as Business.IT._21c.AddonFW.PropertyIsMailHeaderAttribute };
}
[解決方案]
var baseProps = from p in this.GetType().GetProperties()
let attr = p.GetCustomAttribute<PropertyIsMailHeaderParamAttribute>()
where attr != null && attr.Type == PropertyIsMailHeaderParamAttribute.ParamType.@base
select new { Property = p, Attribute = attr as Business.IT._21c.AddonFW.PropertyIsMailHeaderParamAttribute };
您要么必須將Attribute
對象(使用常規轉換或例如使用OfType<>
擴展)轉換為您的類型,但最簡單的方法是使用GetCustomAttribute<>
的通用版本:
var props = from p in this.GetType().GetProperties()
let attr = p.GetCustomAttribute<PropertyIsMailHeaderAttribute>()
where attr != null && attr.HeaderAttribute == "FooBar"
&& attr.Type = ParamType.open
select whatever;
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