Type.GetProperty Method (String, Type, array<Type[], array<ParameterModifier[])
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Searches for the specified public property whose parameters match the specified argument types and modifiers.
Namespace: System
Assembly: mscorlib (in mscorlib.dll)
Syntax
'Declaration
Public Function GetProperty ( _
name As String, _
returnType As Type, _
types As Type(), _
modifiers As ParameterModifier() _
) As PropertyInfo
public PropertyInfo GetProperty(
string name,
Type returnType,
Type[] types,
ParameterModifier[] modifiers
)
Parameters
- name
Type: System.String
The String containing the name of the public property to get.
- returnType
Type: System.Type
The return type of the property.
- types
Type: array<System.Type[]
An array of Type objects representing the number, order, and type of the parameters for the indexed property to get.
-or-
An empty array of the type Type (that is, Type[] types = new Type[0]) to get a property that is not indexed.
- modifiers
Type: array<System.Reflection.ParameterModifier[]
An array of ParameterModifier objects representing the attributes associated with the corresponding element in the types array. The default binder does not process this parameter.
Return Value
Type: System.Reflection.PropertyInfo
A PropertyInfo object representing the public property that matches the specified requirements, if found; otherwise, nulla null reference (Nothing in Visual Basic).
Exceptions
| Exception | Condition |
|---|---|
| AmbiguousMatchException | More than one property is found with the specified name and matching the specified argument types and modifiers. |
| ArgumentNullException | name is nulla null reference (Nothing in Visual Basic). -or- types is nulla null reference (Nothing in Visual Basic). |
| ArgumentException | types is multidimensional. -or- modifiers is multidimensional. -or- types and modifiers do not have the same length. |
| NullReferenceException | An element of types is nulla null reference (Nothing in Visual Basic). |
Remarks
A property is considered public to reflection if it has at least one accessor that is public. Otherwise the property is considered private, and you must use BindingFlags.NonPublic | BindingFlags.Instance | BindingFlags.Static (in Visual Basic, combine the values using Or) to get it.
Although the default binder does not process ParameterModifier (the modifiers parameter), you can use the abstract System.Reflection.Binder class to write a custom binder that does process modifiers. ParameterModifier is only used when calling through COM interop, and only parameters that are passed by reference are handled.
The types array and the modifiers array have the same length. A parameter specified in the types array can have the following attributes, which are specified in the modifiers array: pdIn, pdOut, pdLcid, pdRetval, pdOptional, and pdHasDefault, which represent [In], [Out], [lcid], [retval], [optional], and a value specifying whether the parameter has a default value. A parameter's associated attributes are stored in the metadata and enhance interoperability.
The search for name is case-sensitive. The search includes public static and public instance properties.
If the current Type represents a constructed generic type, this method returns the PropertyInfo with the type parameters replaced by the appropriate type arguments.
If the current Type represents a type parameter in the definition of a generic type or generic method, this method searches the properties of the class constraint.
Indexers and Default Properties
Visual Basic 2005, Visual C# 2005, and Visual C++ 2005 have simplified syntax for accessing indexed properties and allow one indexed property to be a default for its type. For example, if the variable myList refers to a List<T>, the syntax myList[3] (myList(3) in Visual Basic) retrieves the element with the index of 3. You can overload the property.
In C#, this feature is called an indexer and cannot be refered to by name. By default, a C# indexer appears in metadata as an indexed property named "Item". However, a class library developer can use the IndexerNameAttribute attribute to change the name of the indexer in the metadata. For example, the String class has an indexer named Chars. Indexed properties created using languages other than C# can have names other than Item, as well.
To determine whether a type has a default property, use the GetCustomAttributes(Type, Boolean) method to test for the DefaultMemberAttribute attribute. If the type has DefaultMemberAttribute, the MemberName property returns the name of the default property.
Platform Notes
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Silverlight for Windows Phone
GetProperty throws NullReferenceException instead of ArgumentNullException when types contains a nulla null reference (Nothing in Visual Basic) element.
Examples
The following example obtains a Type object corresponding to MyPropertyClass, and the indexed property of this class is retrieved using the arguments passed to the GetProperty method.
.gif "Note") Note: |
|---|
To run this example, see Building Examples That Use a Demo Method and a TextBlock Control. |
Imports System.Reflection
Public Class MyPropertyClass
Private myPropertyArray(9, 9) As Integer
' Declare an indexer.
Default Public Property Item(ByVal i As Integer, ByVal j As Integer) As Integer
Get
Return myPropertyArray(i, j)
End Get
Set(ByVal Value As Integer)
myPropertyArray(i, j) = Value
End Set
End Property
End Class 'MyPropertyClass
Public Class Example
Public Shared Sub Demo(ByVal outputBlock As System.Windows.Controls.TextBlock)
Try
Dim myType As Type = GetType(MyPropertyClass)
Dim myTypeArray(1) As Type
' Create an instance of a Type array representing the number, order
' and type of the parameters for the property.
myTypeArray.SetValue(GetType(Integer), 0)
myTypeArray.SetValue(GetType(Integer), 1)
' Search for the indexed property whose parameters match the
' specified argument types and modifiers.
Dim myPropertyInfo As PropertyInfo = myType.GetProperty("Item", _
GetType(Integer), myTypeArray, Nothing)
outputBlock.Text &= myType.FullName + "." + myPropertyInfo.Name + _
" has a property type of " + myPropertyInfo.PropertyType.ToString() & vbCrLf
Catch ex As Exception
outputBlock.Text &= "An exception occurred " + ex.Message.ToString() & vbCrLf
End Try
End Sub 'Main
End Class 'MyTypeClass
using System;
using System.Reflection;
public class MyPropertyClass
{
private int[,] myPropertyArray = new int[10, 10];
// Declare an indexer.
public int this[int i, int j]
{
get
{
return myPropertyArray[i, j];
}
set
{
myPropertyArray[i, j] = value;
}
}
}
public class Example
{
public static void Demo(System.Windows.Controls.TextBlock outputBlock)
{
try
{
Type myType = typeof(MyPropertyClass);
Type[] myTypeArray = new Type[2];
// Create an instance of the Type array representing the number, order
// and type of the parameters for the property.
myTypeArray.SetValue(typeof(int), 0);
myTypeArray.SetValue(typeof(int), 1);
// Search for the indexed property whose parameters match the
// specified argument types and modifiers.
PropertyInfo myPropertyInfo = myType.GetProperty("Item",
typeof(int), myTypeArray, null);
outputBlock.Text += myType.FullName + "." + myPropertyInfo.Name +
" has a property type of " + myPropertyInfo.PropertyType + "\n";
}
catch (Exception ex)
{
outputBlock.Text += "An exception occurred " + ex.Message + "\n";
}
}
}
Version Information
Silverlight
Supported in: 5, 4, 3
Silverlight for Windows Phone
Supported in: Windows Phone OS 7.1, Windows Phone OS 7.0
XNA Framework
Supported in: Xbox 360, Windows Phone OS 7.0
Platforms
For a list of the operating systems and browsers that are supported by Silverlight, see Supported Operating Systems and Browsers.