CODEWITHSUNDEEP
c#reflection
simpleman
simpleman

Reputation: 148

How to convert un-reference-type Object to actual object

Maybe this question make you confuse ,but please help me

In .NET 4.0 , language C#

I have two project ,one is the library define classes and attribute mark infors for class, one is the project that process reflection of class declared from that library.

The problem is , without make reference to library , I just use reflection-related classes to read assembly and I have to get value of properties that declared in object class.

For example

---In LIB project , named lib.dll

public class MarkAttribute: Attribute
{
    public string A{get;set;}
    public string B{get;set;}
}

[Mark(A="Hello" B="World")]
public class Data
{
}

---In Reflection project

public void DoIt()
{
   string TypeName="Lib.Data";
   var asm=Assembly.LoadFrom("lib.dll");
   foreach (var x in asm.GetTypes())
   {
      if (x.GetType().Name=="Data")
      {
        var obj=x.GetType().GetCustomAttributes(false);

        //now if i make reference to lib.dll in the usual way , it is ok
        var mark=(Lib.MarkAttribute)obj;
        var a=obj.A ; 
        var b=obj.B ;

       //but if i do not make that ref
       //how can i get  A,B value
      }
   }
}

any idea appreciated

Upvotes: 2

Views: 339

Answers (5)

Sven
Sven

Reputation: 22673

You can retrieve the attribute's properties using reflection as well:

Assembly assembly = Assembly.LoadFrom("lib.dll");
Type attributeType = assembly.GetType("Lib.MarkAttribute");
Type dataType = assembly.GetType("Lib.Data");
Attribute attribute = Attribute.GetCustomAttribute(dataType, attributeType);
if( attribute != null )
{
    string a = (string)attributeType.GetProperty("A").GetValue(attribute, null);
    string b = (string)attributeType.GetProperty("B").GetValue(attribute, null);
    // Do something with A and B
}

Upvotes: 2

Alex Aza
Alex Aza

Reputation: 78447

var assembly = Assembly.Load("lib.dll");
dynamic obj = assembly.GetType("Lib.Data").GetCustomAttributes(false)[0];
var a = obj.A;
var b = obj.B;

Upvotes: 0

carlosfigueira
carlosfigueira

Reputation: 87218

You need to remove many of the GetTypes() calls, since you already have a Type object. Then you can use GetProperty to retrieve the property of the custom attribute.

foreach (var x in asm.GetTypes())
{
   if (x.Name=="Data")
   {
       var attr = x.GetCustomAttributes(false)[0]; // if you know that the type has only 1 attribute
       var a = attr.GetType().GetProperty("A").GetValue(attr, null);
       var b = attr.GetType().GetProperty("B").GetValue(attr, null);
    }
}

Upvotes: 1

BrokenGlass
BrokenGlass

Reputation: 160852

If you know the names of the properties you could use dynamic instead of reflection:

 dynamic mark = obj;
 var a = obj.A; 
 var b = obj.B;

Upvotes: 3

Elisha
Elisha

Reputation: 23770

You can invoke the getter of the property:

var attributeType = obj.GetType();
var propertyA = attributeType.GetProperty("A");
object valueA = propertyA.GetGetMethod().Invoke(obj, null)

Upvotes: 2

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