Finding correct property implementing an interface - c#

So, I thaught I have a solution for getting a PropertyInfo when having a concrete class, and a PropertyInfo for an interface implemented by the concrete class. Here is the code:
public static PropertyInfo GetImplementingProperty(Type concreteType, PropertyInfo interfaceProperty)
{
// do some region parameter check, skipped
var interfaceType = interfaceProperty.DeclaringType;
//use the set method if we have a write only property
var getCorrectMethod = interfaceProperty.GetGetMethod() == null
? (Func<PropertyInfo, MethodInfo>) (p => p.GetSetMethod(true))
: p => p.GetGetMethod(true);
var propertyMethod = getCorrectMethod(interfaceProperty);
var mapping = concreteType.GetInterfaceMap(interfaceType);
MethodInfo targetMethod = null;
for (var i = 0; i < mapping.InterfaceMethods.Length; i++)
{
if (mapping.InterfaceMethods[i] == propertyMethod)
{
targetMethod = mapping.TargetMethods[i];
break;
}
}
foreach (var property in concreteType.GetProperties(
BindingFlags.Instance | BindingFlags.GetProperty |
BindingFlags.Public | BindingFlags.NonPublic)) // include non-public!
{
if (targetMethod == getCorrectMethod(property)) // include non-public!
{
return property;
}
}
throw new InvalidOperationException("The property {0} defined on the interface {1} has not been found on the class {2}. That should never happen."
.FormatText(interfaceProperty.Name, interfaceProperty.DeclaringType.FullName, concreteType.FullName));
}
Unfortunately I found a case where it fails, and I am unsure how to fix this.
So I have in a dll a class:
public abstract class BaseClass
{
public Guid ConfigId { get; set; }
public virtual Guid ConfigId2 { get; set; }
}
Then in another dll I do:
interface INamed
{
Guid ConfigId { get; }
Guid ConfigId2 { get; }
}
private class SuperClass : BaseClass, INamed
{
}
Now
ReflectionHelper.GetImplementingProperty(typeof(SuperClass), typeof(INamed).GetProperty("ConfigId2")); // this works
ReflectionHelper.GetImplementingProperty(typeof(SuperClass), typeof(INamed).GetProperty("ConfigId")); // this fails
Any idea how do I match up the ConfigId property to the Base class proprety definition?
PS. I have attributes on the concrete class properties, thats why i need to get those.
Any help appreciated!

You need to add BindingFlags.FlattenHierarchy to your GetProperties call in order to get parent class properties. See the documentation at https://msdn.microsoft.com/en-us/library/kyaxdd3x(v=vs.110).aspx

Related

Getting the DisplayNameAttribute from an Internal class

I have a class that is declared Internal. It is decorated with various annotations. In particular is the [DisplayName("My Display Name")] annotation. I have some code that will retrieve the value but only works if the class is declared public. I am sort of new to using reflection. I believe I need to specify that the BindingFlags.NonPublic be used but I am not sure where.
LinqPAD code:
void Main()
{
List<SpGetProfileInfoResult> p = new List<SpGetProfileInfoResult>();
p.Add(new SpGetProfileInfoResult() { FName = "Eric" });
p.Add(new SpGetProfileInfoResult() { FName = "Mike" });
p.Dump();
foreach (var item in p)
{
Console.WriteLine(item.DisplayName(i => i.FName));
Console.WriteLine(item.FName);
}
}
public partial class SpGetProfileInfoResult
{
// Uncomment this annotation to see that this part will work
// [System.ComponentModel.DisplayNameAttribute("[BILLTO-FNAME]")]
public string FName { get; set; }
}
public partial class SpGetProfileInfoResult
{
internal class Metadata
{
// This attribute is never available seems.
[System.ComponentModel.DisplayNameAttribute("[BILL-FNAME]")]
public string FName { get; set; }
}
}
public static class Tag
{
public static T GetAttribute<T>(this MemberInfo member, bool isRequired) where T : Attribute
{
var attribute = member.GetCustomAttributes(typeof(T), false).SingleOrDefault();
if (attribute == null && isRequired)
{
throw new ArgumentException(
string.Format(
"The {0} attribute must be defined on member {1}",
typeof(T).Name,
member.Name));
}
return (T)attribute;
}
public static string DisplayName<T>(this T src,Expression<Func<T, object>> propertyExpression)
{
Type metadata = null;
var memberInfo = GetPropertyInformation(propertyExpression.Body);
if (memberInfo == null)
{
throw new ArgumentException(
"No property reference expression was found.",
"propertyExpression");
}
var attr = memberInfo.GetAttribute<DisplayNameAttribute>(false);
if (attr == null)
{
return memberInfo.Name;
}
return attr.DisplayName;
}
public static MemberInfo GetPropertyInformation(Expression propertyExpression)
{
MemberExpression memberExpr = propertyExpression as MemberExpression;
if (memberExpr == null)
{
UnaryExpression unaryExpr = propertyExpression as UnaryExpression;
if (unaryExpr != null && unaryExpr.NodeType == ExpressionType.Convert)
{
memberExpr = unaryExpr.Operand as MemberExpression;
}
}
if (memberExpr != null && memberExpr.Member.MemberType == MemberTypes.Property)
{
return memberExpr.Member;
}
return null;
}
}
Usage:
If you don't have LinqPAD, you should download it then you can test this pretty easily by just creating a new C# Program in LinkPAD
Debug.WriteLine(item.DisplayName(i => i.FName));
So it looks like you want to be able to decorate existing members of a partial class, by providing metadata in a separate partial piece. There's no built-in mechanism for that (see eg this question and the classes mentioned in the answer), but if you're willing to stick to a convention, you can roll your own:
So suppose we have
public partial class SpGetProfileInfoResult
{
public string FName { get; set; }
}
in a partial piece we can't change, and
public partial class SpGetProfileInfoResult
{
internal class Metadata
{
[System.ComponentModel.DisplayNameAttribute("[BILL-FNAME]")]
public string FName { get; set; }
}
}
in a partial piece we can change. You already have most of the pieces: in DisplayName(), you successfully determine that we are looking at the FName property; you then look for a DisplayNameAttribute on T.FName, but there isn't one, so that's where it stops.
What you need to do is, in the case where you don't find the attribute you need,
var attr = memberInfo.GetAttribute<DisplayNameAttribute>(false);
if (attr == null)
{
Look for a nested class named Metadata - note here is one place we use BindingFlags.NonPublic
// Try and get a nested metadata class
var metadataType = typeof(T)
.GetNestedType("Metadata",
BindingFlags.Public | BindingFlags.NonPublic);
If we find one:
if (metadataType != null)
{
Look for a member of the same name as was originally being talked about (BindingFlags.NonPublic again)
var membersOnMetadataType = metadataType.GetMember(memberInfo.Name,
BindingFlags.Instance |
BindingFlags.Public |
BindingFlags.NonPublic);
If there is one, use your helper method, but this time pass it the metadata type's member:
if (membersOnMetadataType.Any())
{
var attrOnMetadataType = membersOnMetadataType[0]
.GetAttribute<DisplayNameAttribute>(false);
return attrOnMetadataType.DisplayName;
(I've omitted a final nullity check here, as well as closing the control flow)
Depending on how distasteful you find that "Metadata" string, you could instead do something declarative with attributes:
have a class-level attribute that goes on SpGetProfileInfoResult (the piece you can change) that points at its Metadata using typeof (this is the approach taken by System.ComponentModel), or
have a class-level attribute that goes on Metadata, to have it claim 'I am a metadata type'. Then instead of searching for a nested class named a fixed string, we would instead search for a nested class having this particular attribute.
After working on this for a while I came up with a Hack. I am sure someone out there can help me clean this up a bit, but this is what I found works. I had to add the "Metadata" nested class to the DeclaringType and then do a GetMember on that result, which returns a collection of members.
public static string DisplayName<T>(this T src, Expression<Func<T, object>> propertyExpression)
{
var memberInfo = GetPropertyInformation(propertyExpression.Body);
var mytype = src.GetType();
string strType = mytype.Name + "+Metadata";
var metaType = Type.GetType(strType);
MemberInfo[] mem = metaType.GetMember(memberInfo.Name);
var att = mem[0].GetCustomAttributes(typeof(DisplayNameAttribute), true).FirstOrDefault() as DisplayNameAttribute;
if (att == null)
return memberInfo.Name;
else
return att.DisplayName;
}
I won't try to debug your code because you're using some classes that I'm not familiar with.
One thing I do know is that MemberInfo does not have a GetAttribute() function. You must be using an extension method there.
However I can tell you that you don't need any special bindingflags just because the type is internal. Only the visibility of the member is important, and in this case it's public.
using System;
using System.ComponentModel;
namespace ConsoleApplication1
{
internal class Metadata
{
[DisplayName("[BILL-FNAME]")]
public string FName { get; set; }
}
class Program
{
static void Main()
{
var memberInfo = typeof(Metadata).GetMember("FName")[0];
var atrributes = memberInfo.GetCustomAttributes(false);
Console.WriteLine(atrributes[0].GetType().Name);
}
}
}
Output:
DisplayNameAttribute

Reflection get type of FieldInfo object?

HI All,
I need to access the class SomeClass which is declared has a private field in the Wrapper class, using Reflection so far i have been able to get private field members . How do i cast it back to its original type so that i could access it properties and other members.
internal class Program
{
private static void Main(string[] args)
{
Wrapper wrap = new Wrapper
{
SOmeProperty = new SomeClass
{
Number = 007
}
};
Type type = wrap.GetType();
FieldInfo[] infos = type.GetFields(BindingFlags.NonPublic | BindingFlags.Instance);
foreach (var item in infos)
{
}
}
}
internal class SomeClass
{
public int Number { get; set; }
}
internal class Wrapper
{
private SomeClass _tempSomeObj;
public SomeClass SOmeProperty
{
get
{
return _tempSomeObj;
}
set
{
_tempSomeObj = value;
}
}
}
I dont know if i understand the question correct. You want the type of the private field (backing field)??
Then you could check the FieldType property of the FieldInfo....
like this:
internal class Program
{
#region Methods
private static void Main(string[] args)
{
var wrap = new Wrapper { SOmeProperty = new SomeClass { Number = 007 } };
Type type = wrap.GetType();
FieldInfo[] fieldInfos = type.GetFields(BindingFlags.NonPublic | BindingFlags.Instance);
foreach (var fieldInfo in fieldInfos)
{
if (fieldInfo.FieldType == typeof(SomeClass))
{
Console.WriteLine("Yap!");
}
}
}
#endregion
}
internal class SomeClass
{
#region Properties
public int Number { get; set; }
#endregion
}
internal class Wrapper
{
#region Properties
public SomeClass SOmeProperty { get; set; }
#endregion
}
Use PropertyInfo instead:
internal class Program
{
private static void Main(string[] args)
{
Wrapper wrap = new Wrapper
{
SOmeProperty = new SomeClass
{
Number = 007
}
};
Type type = wrap.GetType();
PropertyInfo info = type.GetProperty("SOmeProperty", BindingFlags.NonPublic | BindingFlags.Instance);
SomeClass value = (SomeClass)info.GetValue(wrap, null);
// use `value` variable here
}
}
I'm still a little fuzzy about what your're trying to do, but you can always GetType() on any object and get its actual run time type and query that for properties field of some other type for example
public void ListPropertiesOfType( object targetObject, Type propertyType ) {
foreach( var foundProperty in targetObject.GetType( ).GetProperties( ).Where( p => p.PropertyType == propertyType ) ) {
Console.WriteLine( "Name: {0}, Value: {1}", foundProperty.Name, foundProperty.GetValue( targetObject, null ) );
}
}
ListPropertiesOfType(new Wrapper(), typeof(SomeClass))
ListPropertiesOfType(new Wrapper(), typeof(SomeOtherClass))
If you want to pass in instances of Someclass and SomeClass that is also fine, just use GetType() on the instances to get the type that you can then use to find properties of that type as illustrated above. this works the same way regardless if you make the method generic and pass in "T" or if its non-generic and you pass in "object"

How to convert variable name to string in c#.net? [duplicate]

This question already has answers here:
Closed 10 years ago.
Possible Duplicate:
Finding the Variable Name passed to a Function in C#
public new Dictionary<string, string> Attributes { get; set; }
public string StringAttributes = string.Empty;
public int? MaxLength { get; set; }
public int? Size { get; set; }
public int? Width { get; set; }
public int? Height { get; set; }
protected override void OnInit(EventArgs e) {
Attributes = new Dictionary<string, string>();
Attributes.Add("MaxLength", MaxLength.ToString());
Attributes.Add("Size", Size.ToString());
Attributes.Add("Width", Width.ToString());
Attributes.Add("Height", Height.ToString());
base.OnInit(e);
}
protected override void OnPreRender(EventArgs e) {
if (Attributes != null) {
StringBuilder attributes = new StringBuilder();
foreach (var item in Attributes) {
if (!string.IsNullOrWhiteSpace(item.Value)) {
attributes.Append(item.Key + "=\"" + item.Value + "\" ");
}
}
StringAttributes = attributes.ToString();
}
}
The problem here is, instead of using Attributes.Add("MaxLength", MaxLength.ToString()); and repeat the same process for other properties, could we not just make a function that is also able to add values to the dictionary, where the keys to be added are their variable names?
Say,
public void addAttribute(object variable){
Attributes = new Dictionary<string, string>();
Attributes.Add(variable.Name, variable.Value);
}...
I guess this is also possible to do with reflection, getting all the nullable properties and looping through them then adding each to the dictionary... But for as long as there are any other ways, we would not stick to reflection.
But if reflection is the only choice, then another problem now would be how to get the nullable properties of the class...
Any help would be greatly appreciated. Thank you.
I can't think of way to do it without reflection.
In order to get all the nullable properties you can you similar code to this:
GetType().GetProperties()
.Where(property =>
property.PropertyType.IsGenericType &&
property.PropertyType.GetGenericTypeDefinition() == typeof(Nullable<>))
Usage example that fills attributes dictionary:
PropertyInfo[] typeProperties = GetType().GetProperties();
var nullableProperties = typeProperties.Where(property =>
property.PropertyType.IsGenericType &&
property.PropertyType.GetGenericTypeDefinition() == typeof(Nullable<>));
var attributes = new Dictionary<string, string>();
foreach (var nullableProperty in nullableProperties)
{
object value = nullableProperty.GetValue(this,null);
attributes.Add(nullableProperty.Name, value == null ?
string.Empty : value.ToString());
}
I'm not sure I fully understand your question without more context, but perhaps this is helpful
If the concern is over reflection overhead for multiple invocations:
Cache that information.
try EmitMapper to fill in values
try AutoMapper to fill in the values
If the problem is getting a variable name via strongly typed compilation then you can use
The Member class I saw on a post from Oliver Hhanappi. Examples of its use are here on my blog
Below is my complete solution. I would say your best bet is to use reflection, as what you're asking is sort of a meta-task. As far as how do you know which properties to add, I would suggest defining your own attribute and applying it to the fields/properties that you want to inspect.
Usage:
Dictionary<string, string> attributes = Inspector<MyClass>.Inspect(target);
The reflection in my sample code is executed once per type inspected, as it is executed within the static constructor of my generic Inspect class:
// apply this attribute to any properties or fields that you want added to the attributes dictionary
[AttributeUsage(
AttributeTargets.Property |
AttributeTargets.Field |
AttributeTargets.Class |
AttributeTargets.Struct |
AttributeTargets.Interface,
AllowMultiple = true, Inherited = true)]
public class InspectAttribute : Attribute
{
// optionally specify the member name explicitly, for use on classes, structs, and interfaces
public string MemberName { get; set; }
public InspectAttribute() { }
public InspectAttribute(string memberName)
{
this.MemberName = memberName;
}
}
public class Inspector<T>
{
// Inspector is a generic class, therefore there will be a separate instance of the _InspectActions variable per type
private static List<Action<Dictionary<string, string>, T>> _InspectActions;
static Inspector()
{
_InspectActions = new List<Action<Dictionary<string, string>, T>>();
foreach (MemberInfo m in GetInspectableMembers(typeof(T)))
{
switch (m.MemberType)
{
case MemberTypes.Property:
{
// declare a separate variable for variable scope with anonymous delegate
PropertyInfo member = m as PropertyInfo;
// create an action delegate to add an entry to the attributes dictionary using the property name and value
_InspectActions.Add(
delegate(Dictionary<string, string> attributes, T item)
{
object value = member.GetValue(item, null);
attributes.Add(member.Name, (value == null) ? "[null]" : value.ToString());
});
}
break;
case MemberTypes.Field:
{
// declare a separate variable for variable scope with anonymous delegate
FieldInfo member = m as FieldInfo;
// need to create a separate variable so that delegates do not share the same variable
// create an action delegate to add an entry to the attributes dictionary using the field name and value
_InspectActions.Add(
delegate(Dictionary<string, string> attributes, T item)
{
object value = member.GetValue(item);
attributes.Add(member.Name, (value == null) ? "[null]" : value.ToString());
});
}
break;
default:
// for all other member types, do nothing
break;
}
}
}
private static IEnumerable<MemberInfo> GetInspectableMembers(Type t)
{
// get all instance fields and properties
foreach (MemberInfo member in t.GetMembers(BindingFlags.NonPublic | BindingFlags.Public | BindingFlags.Instance | BindingFlags.FlattenHierarchy | BindingFlags.GetField | BindingFlags.GetProperty))
{
// check if the current member is decorated with an Inspect attribute
object[] inspectAttributes = member.GetCustomAttributes(typeof(InspectAttribute), true);
if (inspectAttributes != null && inspectAttributes.Length > 0)
{
yield return member;
}
}
// now look for any Inspect attributes defined at the type level
InspectAttribute[] typeLevelInspectAttributes = (InspectAttribute[])t.GetCustomAttributes(typeof(InspectAttribute), true);
if (typeLevelInspectAttributes != null && typeLevelInspectAttributes.Length > 0)
{
foreach (InspectAttribute attribute in typeLevelInspectAttributes)
{
// search for members matching the name provided by the Inspect attribute
MemberInfo[] members = t.GetMember(attribute.MemberName, BindingFlags.NonPublic | BindingFlags.Public | BindingFlags.Instance | BindingFlags.GetField | BindingFlags.GetProperty | BindingFlags.FlattenHierarchy);
if (members != null && members.Length > 0)
{
foreach (MemberInfo member in members)
{
yield return member;
}
}
}
}
}
public static Dictionary<string, string> Inspect(T item)
{
// create a new attributes dictionary
Dictionary<string, string> attributes = new Dictionary<string, string>();
foreach (Action<Dictionary<string, string>, T> inspectAction in _InspectActions)
{
// execute each "inspect" action.
// This will execute the delegates we created earlier, causing entries to be added to the dictionary
inspectAction(attributes, item);
}
return attributes;
}
}
public class BasePage
{
public int? SomeValue { get; set; }
}
// example class with properties decorated with the Inspect attribute
[Inspect("SomeValue")] // also inspect the "SomeValue" property from the BasePage class
public class MyPage : BasePage
{
[Inspect]
public int? MaxLength { get; set; }
[Inspect]
public int? Size { get; set; }
[Inspect]
public int? Width { get; set; }
[Inspect]
public int? Height { get; set; }
public string GenerateAttributeString()
{
System.Text.StringBuilder attributes = new System.Text.StringBuilder();
foreach (KeyValuePair<string, string> item in Inspector<MyPage>.Inspect(this))
{
attributes.Append(item.Key + "=\"" + item.Value + "\" ");
}
return attributes.ToString();
}
}
You can use the following function to extract out the public Nullable properties from a class into the format your looking for. It also calls the getter method for the value.
This is using the same reflection use that #Elisha talked about. Also it does a .ToString() call to the value returned by the getter.
IDictionary<string, string> GetProps<T>(T DataObject)
{
if(null == DataObject)
return new Dictionary<string, string>();
var nullableProperties =
from property in typeof(T).GetProperties(BindingFlags.Instance | BindingFlags.Public)
from accessor in property.GetAccessors(false)
let returnType = accessor.ReturnType
where returnType.IsGenericType
&& returnType.GetGenericTypeDefinition() == typeof(Nullable<>)
&& accessor.GetParameters().Length == 0
select new { Name=property.Name, Getter=accessor};
return nullableProperties.ToDictionary(
x => x.Name,
x => x.Getter.Invoke(DataObject, null).ToString());
}

AmbiguousMatchException - Type.GetProperty - C# Reflection

Yesterday I ran into an Issue while developing a Web Part (This question is not about webpart but about C#). Little background about the Issue. I have a code that load the WebPart using the Reflection, In which I got the AmbiguousMatchException. To reproduce it try the below code
public class TypeA
{
public virtual int Height { get; set; }
}
public class TypeB : TypeA
{
public String Height { get; set; }
}
public class Class1 : TypeB
{
}
Assembly oAssemblyCurrent = Assembly.GetExecutingAssembly();
Type oType2 = oAssemblyCurrent.GetType("AmbigousMatchReflection.Class1");
PropertyInfo oPropertyInfo2 = oType2.GetProperty("Height");//Throws AmbiguousMatchException
oPropertyInfo2 = oType2.GetProperty("Height",
BindingFlags.DeclaredOnly | BindingFlags.Public | BindingFlags.Instance); // I tried this code Neither these BindingFlags or any other didnt help
I wanted to know the BindingFlag to Fetch the Height Property. You will have the question of why I wanted to create another Height Property that is already there in the Base class. That is how the Microsoft.SharePoint.WebPartPages.PageViewerWebPart was designed check the Height property of the PageViewerWebPart class.
There are two Height properties there, and neither of them are declared by Class1 which you're calling GetProperty on.
Now, would it be fair to say you're looking for "the Height property declared as far down the type hiearchy as possible"? If so, here's some code to find it:
using System;
using System.Diagnostics;
using System.Reflection;
public class TypeA
{
public virtual int Height { get; set; }
}
public class TypeB : TypeA
{
public new String Height { get; set; }
}
public class Class1 : TypeB
{
}
class Test
{
static void Main()
{
Type type = typeof(Class1);
Console.WriteLine(GetLowestProperty(type, "Height").DeclaringType);
}
static PropertyInfo GetLowestProperty(Type type, string name)
{
while (type != null)
{
var property = type.GetProperty(name, BindingFlags.DeclaredOnly |
BindingFlags.Public |
BindingFlags.Instance);
if (property != null)
{
return property;
}
type = type.BaseType;
}
return null;
}
}
Note that if you know the return types will be different, it may be worth simplifying the code as shown in sambo99's answer. That would make it quite brittle though - changing the return type later could then cause bugs which would only be found at execution time. Ouch. I'd say that by the time you've done this you're in a brittle situation anyway :)
See the following example:
class Foo {
public float Height { get; set; }
}
class Bar : Foo {
public int Height { get; set; }
}
class BarBar : Bar { }
class Foo2 : Foo{
public float Height { get; set; }
}
class BarBar2 : Foo2 { }
static void Main(string[] args) {
// works
var p = typeof(BarBar).GetProperty("Height", typeof(float), Type.EmptyTypes);
// works
var p2 = typeof(BarBar).BaseType.GetProperty("Height", BindingFlags.DeclaredOnly | BindingFlags.Public | BindingFlags.Instance);
// works
var p3 = typeof(BarBar2).GetProperty("Height");
// fails
var p4 = typeof(BarBar).GetProperty("Height");
Console.WriteLine(p);
}
You get an AmbiguousMatchException if a two or more properties with the differing return types and the same name live in your inheritance chain.
Stuff resolves just fine if you override an implementation (using new or override) and maintain the return type.
You can force reflection only to look at the properties for a particular type.
Obviously there are two properties that match the name you have given of "Height", one with return type int, and another string., Just add the return type as the second parameter tot the GetPropertyCall depending on which you want returning and this ambiguity should disappear.
I created two extension methods extending on Jon Skeet's answer. You can place those in any public static class.
Edit: Removed the MissingMemberException to behave more like the default .NET implementations which return null on failure.
Usage:
var field = type.GetFieldUnambiguous(type, "FieldName", bindingFlags);
var property = type.GetPropertyUnambiguous(type, "PropertyName", bindingFlags);
Implementation:
public static FieldInfo GetFieldUnambiguous(this Type type, string name, BindingFlags flags)
{
if (type == null) throw new ArgumentNullException(nameof(type));
if (name == null) throw new ArgumentNullException(nameof(name));
flags |= BindingFlags.DeclaredOnly;
while (type != null)
{
var field = type.GetField(name, flags);
if (field != null)
{
return field;
}
type = type.BaseType;
}
return null;
}
public static PropertyInfo GetPropertyUnambiguous(this Type type, string name, BindingFlags flags
{
if (type == null) throw new ArgumentNullException(nameof(type));
if (name == null) throw new ArgumentNullException(nameof(name));
flags |= BindingFlags.DeclaredOnly;
while (type != null)
{
var property = type.GetProperty(name, flags);
if (property != null)
{
return property;
}
type = type.BaseType;
}
return null;
}

How do I use reflection to get properties explicitly implementing an interface?

More specifically, if I have:
public class TempClass : TempInterface
{
int TempInterface.TempProperty
{
get;
set;
}
int TempInterface.TempProperty2
{
get;
set;
}
public int TempProperty
{
get;
set;
}
}
public interface TempInterface
{
int TempProperty
{
get;
set;
}
int TempProperty2
{
get;
set;
}
}
How do I use reflection to get all the propertyInfos for properties explicitly implementing TempInterface?
Thanks.
I think the class you are looking for is System.Reflection.InterfaceMapping.
Type ifaceType = typeof(TempInterface);
Type tempType = typeof(TempClass);
InterfaceMapping map = tempType.GetInterfaceMap(ifaceType);
for (int i = 0; i < map.InterfaceMethods.Length; i++)
{
MethodInfo ifaceMethod = map.InterfaceMethods[i];
MethodInfo targetMethod = map.TargetMethods[i];
Debug.WriteLine(String.Format("{0} maps to {1}", ifaceMethod, targetMethod));
}
The property getter and setter of an explicitly implemented interface property has an unusual attribute. It's IsFinal property is True, even when it is not a member of a sealed class. Try this code to verify my assertion:
foreach (AssemblyName name in Assembly.GetEntryAssembly().GetReferencedAssemblies()) {
Assembly asm = Assembly.Load(name);
foreach (Type t in asm.GetTypes()) {
if (t.IsAbstract) continue;
foreach (MethodInfo mi in t.GetMethods(BindingFlags.NonPublic | BindingFlags.Instance)) {
int dot = mi.Name.LastIndexOf('.');
string s = mi.Name.Substring(dot + 1);
if (!s.StartsWith("get_") && !s.StartsWith("set_")) continue;
if (mi.IsFinal)
Console.WriteLine(mi.Name);
}
}
}
Here's a modified solution based on the implementation given in this blog post:
var explicitProperties =
from prop in typeof(TempClass).GetProperties(
BindingFlags.NonPublic | BindingFlags.Instance | BindingFlags.DeclaredOnly)
let getAccessor = prop.GetGetMethod(true)
where getAccessor.IsFinal && getAccessor.IsPrivate
select prop;
foreach (var p in explicitProperties)
Console.WriteLine(p.Name);
Building on the answer by MrKurt:
var targetMethods =
from iface in typeof(TempClass).GetInterfaces()
from method in typeof(TempClass).GetInterfaceMap(iface).TargetMethods
select method;
var explicitProps =
from prop in typeof(TempClass).GetProperties(BindingFlags.Instance |
BindingFlags.NonPublic)
where targetMethods.Contains(prop.GetGetMethod(true)) ||
targetMethods.Contains(prop.GetSetMethod(true))
select prop;
I had to modify Jacob Carpenter's answer but it works nicely. nobugz's also works but Jacobs is more compact.
var explicitProperties =
from method in typeof(TempClass).GetMethods(BindingFlags.NonPublic | BindingFlags.Instance)
where method.IsFinal && method.IsPrivate
select method;
A simple helper class that could help:
public class InterfacesPropertiesMap
{
private readonly Dictionary<Type, PropertyInfo[]> map;
public InterfacesPropertiesMap(Type type)
{
this.Interfaces = type.GetInterfaces();
var properties = type.GetProperties(BindingFlags.NonPublic | BindingFlags.Instance | BindingFlags.Public);
this.map = new Dictionary<Type, PropertyInfo[]>(this.Interfaces.Length);
foreach (var intr in this.Interfaces)
{
var interfaceMap = type.GetInterfaceMap(intr);
this.map.Add(intr, properties.Where(p => interfaceMap.TargetMethods
.Any(t => t == p.GetGetMethod(true) ||
t == p.GetSetMethod(true)))
.Distinct().ToArray());
}
}
public Type[] Interfaces { get; private set; }
public PropertyInfo[] this[Type interfaceType]
{
get { return this.map[interfaceType]; }
}
}
You'll get properties for each interface, even explicitly implemented.
It's overly complex. You have to reflect over the methods/properties of the Interface type, see if they exist in your class type, and compare them to see if they're the "same" when they do exist.
If something is in the interface but not the type you're testing, it's an explicit implementation. If it's in both, but different between the two, it's an explicit interface.
This seems a bit painful for no apparent reason!
My solution is for the case where you know the name of the property you are looking for and is pretty simple.
I have a class for making reflection a bit easier that I just had to add this case to:
public class PropertyInfoWrapper
{
private readonly object _parent;
private readonly PropertyInfo _property;
public PropertyInfoWrapper(object parent, string propertyToChange)
{
var type = parent.GetType();
var privateProperties= type.GetProperties(BindingFlags.NonPublic | BindingFlags.Instance);
var property = type.GetProperty(propertyToChange) ??
privateProperties.FirstOrDefault(p => UnQualifiedNameFor(p) == propertyName);
if (property == null)
throw new Exception(string.Format("cant find property |{0}|", propertyToChange));
_parent = parent;
_property = property;
}
private static string UnQualifiedNameFor(PropertyInfo p)
{
return p.Name.Split('.').Last();
}
public object Value
{
get { return _property.GetValue(_parent, null); }
set { _property.SetValue(_parent, value, null); }
}
}
You cant just do == on name because explicitly implemented properties have fully qualified names.
GetProperties needs both the search flags to get at private properties.
Jacob's code is missing a filter:
var props = typeof(TempClass).GetInterfaces().Where(i => i.Name=="TempInterface").SelectMany(i => i.GetProperties());
foreach (var prop in props)
Console.WriteLine(prop);

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