c# 反射，如何获得泛型类型 class 属性

Question

I have a Generic type List<Shift> where

public class Shift
{
    [DisplayFormat(DataFormatString = "dd-MMM-yyy '(hours)'")]
    public DateTimeOffset Date { get; set; }

    [DisplayFormat(DataFormatString = "hh':'mm")]
    public TimeSpan TimeWorked { get; set; }
}

I'm trying to get schedule props with attributes using reflection

var props = typeof(List<ShiftDayItem>).GetProperties();
var ShiftProperty = props.Last();

But ShiftProperty contains no attributes, so I can't access Date or TimeWorked. Is reflection not aware of these or is there another way for me to get those properties? Thanks!

Answer 1

I think you are misunderstanding what "Properties" are in c#. Your Shift class has 2 properties: "Date" and "TimeWorked". To get info about these 2 properties you can simply write: typeof(Shift).GetProperties() . You are calling typeof(List<ShiftDayItem>).GetProperties() which will give you properties of List class: Count, Capacity, etc.. these are entirely unrelated.

Answer 2

I think you want to get attributes from Shift properties. To do this you need to get the generic parameter T from List<T> . To achive this you can do this

// Gets the generic type T from List<T>, in your case Shift
// Replace 'typeof(List<Shift>)' with your actual list
Type listType = typeof(List<Shift>).GenericTypeArguments[0];

To get all attributes from the type Shift you first need to get all the properites from which you can get the attributes.

// Gets all properties from the generic type T
PropertyInfo[] shiftProperties = listType.GetProperties();

Now that you have all the properties you can get the attributes

// Gets all Attributes from each property and puts them in one list (SelectMany)
IEnumerable<Attribute> attributes = shiftProperties.SelectMany(prop => prop.GetCustomAttributes());

You get IEnumerable<Attribute> from each property, which would result in IEnumerable<IEnumerable<Attribute>> which is not what we want. We used the method SelectMany which takes each IEnumerable and flattens it into one. When you put everything together you get this

// Gets the generic type T from List<T>, in your case Shift
// Replace 'typeof(List<Shift>)' with your actual list
Type listType = typeof(List<Shift>).GenericTypeArguments[0];

// Gets all properties from the generic type T
PropertyInfo[] shiftProperties = listType.GetProperties();

// Gets all Attributes from each property and puts them in one list (SelectMany)
IEnumerable<Attribute> attributes = shiftProperties.SelectMany(prop => prop.GetCustomAttributes());

Answer 3

You need more code:

Dim shifttprops= ShiftProperty.PropertyType.GetProperties()
For Each prop in shifttprops
   Dim attrs = prop.CustomAttributes
Next

Note the use of CustomAttributes instead of Attributes