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How to: Query An Assembly's Metadata with Reflection (LINQ) (Visual Basic)

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The following example shows how LINQ can be used with reflection to retrieve specific metadata about methods that match a specified search criterion. In this case, the query will find the names of all the methods in the assembly that return enumerable types such as arrays.

Example

Imports System.Linq
Imports System.Reflection  

Module Module1  
    Sub Main()  
        Dim asmbly As Assembly =
            Assembly.Load("System.Core, Version=3.5.0.0, Culture=neutral, PublicKeyToken= b77a5c561934e089")  
  
        Dim pubTypesQuery = From type In asmbly.GetTypes()
                            Where type.IsPublic
                            From method In type.GetMethods()
                            Where method.ReturnType.IsArray = True
                            Let name = method.ToString()
                            Let typeName = type.ToString()
                            Group name By typeName Into methodNames = Group  
  
        Console.WriteLine("Getting ready to iterate")  
        For Each item In pubTypesQuery  
            Console.WriteLine(item.methodNames)  
  
            For Each type In item.methodNames  
                Console.WriteLine(" " & type)  
            Next  
        Next  
        Console.WriteLine("Press any key to exit... ")  
        Console.ReadKey()  
    End Sub  
End Module

The example uses the Assembly.GetTypes method to return an array of types in the specified assembly. The Where Clause filter is applied so that only public types are returned. For each public type, a subquery is generated by using the MethodInfo array that is returned from the Type.GetMethods call. These results are filtered to return only those methods whose return type is an array or else a type that implements IEnumerable<T>. Finally, these results are grouped by using the type name as a key.

See also