How can I now in a list obtained with Type.GetProperties() if the properties are user-defined?
For example
class test
{
public string propertyOne{get;set;}
public string propertyTwo{get;set;}
}
With typeof(test).GetProperties() I get two PropertyInfo, how can I now they are user defined?
Information about the context, here is the test that should pass
[Test]
public void GetFullNameScalarPropertiesTest()
{
// Act
var properties = ReflectionHelper.GetFullNameScalarProperties(typeof(Parent));
// Assert
Assert.True(properties.Contains("PropertyOne"));
Assert.True(properties.Contains("Child.PropertyTwo"));
Assert.True(properties.Contains("Child.GrandChild.PropertyThree"));
Assert.That(properties.Count, Is.EqualTo(3));
}
class Parent
{
public Parent()
{
Child = new Child();
}
public string PropertyOne { get; set; }
public Child Child { get; set; }
}
class Child
{
public Child()
{
GrandChild = new GrandChild();
}
public string PropertyTwo { get; set; }
public GrandChild GrandChild { get; set; }
}
class GrandChild
{
public string PropertyThree { get; set; }
}
So, in a recursive method I'm getting properties and creating a list with the names
ATM the code that pass this test is
public static IList<string> GetFullNameScalarProperties(Type type)
{
var lista = new List<string>();
var path = string.Empty;
var properties = type.GetProperties();
foreach (var propertyInfo in properties)
GetFullNameScalarProperties(propertyInfo, path, lista);
return lista;
}
private static void GetFullNameScalarProperties(PropertyInfo propertyInfo, string path, ICollection<string> lista)
{
if (!string.IsNullOrEmpty(path))
path += ".";
path += propertyInfo.Name;
if (propertyInfo.PropertyType.FullName != null)
if (propertyInfo.PropertyType.FullName.StartsWith("System"))
{
lista.Add(path);
return;
}
var properties = propertyInfo.PropertyType.GetProperties();
foreach (var pi in properties)
GetFullNameScalarProperties(pi, path, lista);
}
It's unclear what you mean by "user-defined" - are you trying to spot the difference between an automatically implemented property and one which has been written by hand? If so, an automatically implemented property will have the [CompilerGenerated] attribute on the getter and the setter.
using System;
using System.Runtime.CompilerServices;
class Program
{
public int AutomaticallyImplemented { get; set; }
public int HandWritten {
get { return 0; }
set {}
}
static void Main()
{
foreach (var property in typeof(Program).GetProperties())
{
bool auto = property.GetGetMethod().IsDefined
(typeof(CompilerGeneratedAttribute), false);
Console.WriteLine("{0}: {1}", property.Name, auto);
}
}
}
Obviously you'd normally want to check whether there is a getter first :)
If you want to get those non-inherited members, try Type.GetProperties, and pass BindingFlags.DeclaredOnly as an argument like:
var properties = typeof(test).GetProperties(BindingFlags.Instance | BindingFlags.Public | BindingFlags.DeclaredOnly);
Maybe you want to know which one aren't .NET Framework ones.
You can invoke Type.GetProperties and iterate found properties with LINQ in order to know where these were defined in your class, and which ones, in framework level.
As others said, you need PropertyInfo.DeclaringType to know where some property was defined.
If any of your project's object are inheriting from some base class, maybe you can do this:
someObject.GetType().GetProperties().Where(propInfo => propInfo.DeclaringType.IsSubclassOf(typeof(ProjectBaseType))
There is nothing like a 'user defined' property. To learn in what type in an inheritance hierarchy a property was declared, have a look at PropertyInfo.DeclaringType.
If you want to findout whether or not a property is inherited compare the PropertyInfo.DeclaringType to the Type you are testing
Related
I want to index class properties like an array.
Public class Foo
{
propery p1{get;set;}
propery p3{get;set;}
propery p3{get;set;}
.
.
.
.
}
I wan to index every propery like an array
FOO.p1=Value
Foo[0]=Value(index 0 refers to p1)
I don't know much about the database, where there might have been a ready-made solution. But at least you can do it by reflection in this way:
using System.Reflection;
[AttributeUsage(AttributeTargets.Property, Inherited = true, AllowMultiple = false)]
public sealed class IndexedPropertyAttribute : Attribute
{
readonly int index;
public IndexedPropertyAttribute(int index)
{
this.index = index;
}
public int Index
{
get { return index; }
}
}
public abstract class WithIndexedProperties
{
private Lazy<IReadOnlyDictionary<int, PropertyInfo>> properties;
protected WithIndexedProperties()
{
properties = new Lazy<IReadOnlyDictionary<int, PropertyInfo>>(
() => {
var linq = from prop in this.GetType().GetProperties()
let attr = prop.GetCustomAttributes(typeof(IndexedPropertyAttribute), true)
where attr.Length is 1
select (((IndexedPropertyAttribute)attr[0]).Index, prop);
return linq.ToDictionary(p => p.Index, p => p.prop);
});
}
public object? this[int propertyIndex]
{
get
{
return properties.Value[propertyIndex].GetValue(this);
}
set
{
properties.Value[propertyIndex].SetValue(this, value);
}
}
}
And there is an example:
Clss obj = new Clss();
obj[0] = "ABC";
obj[2] = 222;
obj[4] = 444;
// Here obj.A will be "ABC", obj.B will be 444 and obj.C will be 222.
public class Clss : WithIndexedProperties
{
[IndexedProperty(0)]
public string? A { get; init; }
[IndexedProperty(4)]
public int B { get; init; }
[IndexedProperty(2)]
public int C { get; init; }
}
I think you need to do something like this. The code below is very generalized solution to your question and I might need some customization for yourself
using System.Reflection;
public class ReflectionBasedIndexedType
{
public int A1 { get; set; } = 10;
public int A2 { get; set; } = 20;
public string SomeString => "Hello There";
private readonly Dictionary<string, object> _underlyingCollection;
public object this[string name] => _underlyingCollection[name];
public ReflectionBasedIndexedType()
{
_underlyingCollection = GetUnderlyingCollection();
}
private Dictionary<string, object> GetUnderlyingCollection()
{
Dictionary<string, object> container = new();
// get the properties defined in the class, I am filtering
// with constraint that, I want get only public and class level
// Properties, which means I won't get any private/protected or
// static properties if there is defined such in the class
// also where filters out indexer property, which we have defined
// inside this class, without this line, there will be exception
IEnumerable<PropertyInfo> properties = GetType()
.GetProperties(BindingFlags.Instance | BindingFlags.Public)
.Where(x => x.GetIndexParameters().Length == 0);
foreach (PropertyInfo property in properties)
{
container.Add(property.Name, property.GetValue(this)!);
}
return container;
}
}
and than use case will be like this
ReflectionBasedIndexedType rbit = new();
var a1 = rbit[nameof(rbit.A1)];
var a2 = rbit[nameof(rbit.A2)];
var str = rbit[nameof(rbit.SomeString)];
Console.WriteLine(a1);
Console.WriteLine(a2);
Console.WriteLine(str);
and output in the console will be this
10
20
Hello There
I think you have two ways at least.
The first one, is #Swapper mentioned, yo can use reflection. In this way, the class is normal and you have to write your hug code in where you want to use that class.
The second way is easier but a little fuzy. You can use dynamic type. If you know how to use it, that's ok. Otherwise please let me know, then I will create a sample code for you.
public void ClickEdit(TItem clickedItem)
{
Crud = CrudEnum.Update;
foreach (PropertyInfo prop in typeof(TItem).GetProperties())
{
prop.SetValue(EditItem, typeof(TItem).GetProperty(prop.Name).GetValue(clickedItem), null);
}
}
I created the above method to loop through an generic typed instance and use the value of that instance to set values in another instance of the same type.
However, some of the TItem properties are read-only, and then exceptions will be thrown.
What is the proper way to skip properties that are read-only and set only the properties that can be set?
Thanks!
you could try to check the CanWrite property:
class Program
{
static void Main(string[] args)
{
Demo demo = new Demo();
foreach (PropertyInfo property in demo.GetType().GetProperties())
{
if (property.CanWrite)
{
property.SetValue(demo, "New value");
}
}
}
}
public class Demo
{
public string ReadOnlyProperty { get; }
public string ReadWriteProperty { get; set; }
}
Best regards
I've been working on a library to generate fake data using Faker.NET. The problem I'm having is that I don't know how to access an anonymous method that I'm passing to the constructor of my DataGenerator child classes.
The issue is that in order to create a list of generics I had to create base class DataGenerator but I cannot pull my Func<T> member up because that base class is not generic so no Tavailable. However, my DataGenerator<T> class does expose the Generator property which is my anonymous method but I haven't found a way to access it while iterating my list of data generators.
Any advice will be highly appreciated.
This is what I have so far:
public class Employee
{
public string FirstName { get; set; }
public string LastName { get; set; }
public Guid EmpUid { get; set; }
}
// Define other methods and classes here
public abstract class DataGenerator
{
public abstract int GetWeight(string matchingProperty);
public abstract Type Type { get;}
}
public abstract class DataGenerator<T> : DataGenerator
{
public readonly string[] Tags;
public readonly Func<T> Generator;
protected DataGenerator(Func<T> generator, params string[] tags)
{
Tags = tags;
//How to access this?
Generator = generator;
}
public override int GetWeight(string matchingProperty)
{
int sum = (from tag in Tags
where matchingProperty.ToLowerInvariant().Contains(tag.ToLowerInvariant())
select 1).Sum();
return sum;
}
public override Type Type {
get { return typeof(T); }
}
}
public class StringDataGenerator : DataGenerator<string>
{
public StringDataGenerator(Func<string> generator, params string[] tags) : base(generator, tags)
{
}
}
public class GuidDataGenerator : DataGenerator<Guid>
{
public GuidDataGenerator(Func<Guid> generator, params string[] tags)
: base(generator, tags)
{
}
}
And I'm testing it here:
private static void Main(string[] args)
{
var dataGeneratorList = new List<DataGenerator>
{
new StringDataGenerator(Name.First, "first", "name"),
new StringDataGenerator(Name.Last, "last", "name"),
new GuidDataGenerator(Guid.NewGuid, "uid", "id")
};
var writeProperties = typeof (Employee).GetProperties().Where(p => p.CanWrite);
foreach (var property in writeProperties)
{
foreach (var dataGenerator in dataGeneratorList)
{
if (property.PropertyType == dataGenerator.Type)
{
var weigth = dataGenerator.GetWeight(property.Name);
//How to access generator here???
var testValue = dataGenerator.Generator.Invoke();
}
}
}
}
As you tagged, given your current setup, reflection is probably your only option.
var func = dataGenerator.GetType().GetField("Generator").GetValue(dataGenerator);
var testValue = func.GetType().GetMethod("Invoke").Invoke(func, null);
I'm not sure anyone could call this super nice, and it won't be super fast, but it's probably sufficient for anything you need fake data in, I suppose.
For good measure, here's it in action.
Your question is actually a bit more complicated than it may seem at face-value. A nice way of handling this if you only ever use it in object form is just to add an abstract Generate method to the base, non-generic class:
public abstract object Generate();
Then override it in your generic one:
public override object Generate()
{
return this.Generator();
}
Of course, this return an object, which isn't nice in a generic class. But at least it avoids reflection.
Another solution to avoid this reflection nonsense might be the use of covariance, although that will, unfortunately, break for value types, like Guid.
public interface IDataGenerator<out T>
{
int GetWeight(string matchingProperty);
Type Type { get;}
T Generate();
}
public abstract class DataGenerator<T> : IDataGenerator<T>
{
public readonly string[] Tags;
public readonly Func<T> Generator;
protected DataGenerator(Func<T> generator, params string[] tags)
{
Tags = tags;
//How to access this?
Generator = generator;
}
public T Generate(){
return this.Generator();
}
. . .
}
That then turns into a preferable,
private static void Main(string[] args)
{
var dataGeneratorList = new List<IDataGenerator<object>>
{
new StringDataGenerator(Name.First, "first", "name"),
new StringDataGenerator(Name.Last, "last", "name")
// But this line doesn't work
// new GuidDataGenerator(Guid.NewGuid, "uid", "id")
};
var writeProperties = typeof (Employee).GetProperties().Where(p => p.CanWrite);
foreach (var property in writeProperties)
{
foreach (var dataGenerator in dataGeneratorList)
{
if (property.PropertyType == dataGenerator.Type)
{
var weigth = dataGenerator.GetWeight(property.Name);
var testValue = dataGenerator.Generate();
}
}
}
}
I have been struggling a bit with some reflection code that I though would be simple. Essentially, I have an interface that defines a method. Then, I have an abstract class that provides a base implementation of that method.
The concrete classes can contain nested instances of other classes that can also derive from the same base class. It can be illustrated by the following sample:
using System.Linq;
public interface ISampleObject
{
bool IsValid();
}
public abstract class SampleObjectBase : ISampleObject
{
public bool IsValid()
{
var returnValue = true;
// Self-validation sets the return value.
var childProperties = this.GetType().GetProperties().Where(pi => typeof(ISampleObject).IsAssignableFrom(pi.PropertyType));
foreach (var childProperty in childProperties)
{
// var childInstance = ????; // Need the actual *existing* instance property, cast to ISampleObject.
// if (childInstance.IsValid() != true)
// {
// returnValue = false;
// }
}
return returnValue;
}
}
public sealed class InnerSampleObject : SampleObjectBase
{
}
public sealed class OuterSampleObject : SampleObjectBase
{
public InnerSampleObject DerivedSampleObject { get; set; }
}
My problem is that in the commented code for SampleObjectBase, I cannot get the concrete instance of the matching PropertyInfo value. If I look at the PropertyInfo object in the loop, I see that the type is correct, but I cannot find a way to directly access the instance that already exists in the implementation. So, when executing, for example, OuterSampleObject.IsValid(), the code finds the PropertyInfo for InnerSampleObject, as expected. I want to execute InnerSampleObject.IsValid().
I have tried (multiple variations of):
var childIsValid = (bool)contractProperty.PropertyType.InvokeMember("IsValid", BindingFlags.InvokeMethod, null, null, null);
And:
var childInstance = (ISampleContract)contractProperty;
The problem with the first one is that I can't pass null in as the target for InvokeMember, as IsValid() is not static (nor can it be, since I am focused on the actual instance). The second on is just a lame cast, but is the gist of what I want to accomplish.
The sample code above is just a minimalist example of what I want to achieve. The full code is part of a self-validating DTO that recursively checks the entire hierarchy and returns what children have validation issues and what they are.
Any help would be greatly appreciated.
How about:
var instance = childProperty.GetValue(this, null) as ISampleObject;
if (instance != null)
{
if (!instance.IsValid())
return false;
}
Please see if the code below is what you are looking for. My changes are marked with a comment starting with //VH:
public interface ISampleObject
{
bool IsValid();
}
public abstract class SampleObjectBase : ISampleObject
{
public virtual bool IsValid()
{
var returnValue = true; //VH: Changed value from false to true
// Self-validation sets the return value.
var childProperties = this.GetType().GetProperties().Where(pi => typeof(ISampleObject).IsAssignableFrom(pi.PropertyType));
foreach (var childProperty in childProperties)
{
//VH: Here is how you get the value of the property
var childInstance = (ISampleObject)childProperty.GetValue(this, null);
if (childInstance.IsValid() != true)
{
returnValue = false;
}
}
return returnValue;
}
}
public sealed class InnerSampleObject : SampleObjectBase
{
}
public sealed class OuterSampleObject : SampleObjectBase
{
//VH: Added this constructor
public OuterSampleObject()
{
DerivedSampleObject = new InnerSampleObject();
}
public InnerSampleObject DerivedSampleObject { get; set; }
}
class Program
{
static void Main(string[] args)
{
OuterSampleObject c = new OuterSampleObject();
c.IsValid();
}
}
Just use
var childInstance = (ISampleObject)childProperty.GetValue(this, null);
I've created a class with properties that have default values. At some point in the object's lifetime, I'd like to "reset" the object's properties back to what they were when the object was instantiated. For example, let's say this was the class:
public class Truck {
public string Name = "Super Truck";
public int Tires = 4;
public Truck() { }
public void ResetTruck() {
// Do something here to "reset" the object
}
}
Then at some point, after the Name and Tires properties have been changed, the ResetTruck() method could be called and the properties would be reset back to "Super Truck" and 4, respectively.
What's the best way to reset the properties back to their initial hard-coded defaults?
You can have the initialization in a method instead of inlining with the declaration. Then have the constructor and reset method call the initialization method:
public class Truck {
public string Name;
public int Tires;
public Truck() {
Init();
}
public void ResetTruck() {
Init();
}
private void Init() {
Name = "Super Truck";
Tires = 4;
}
}
Another way is not to have a reset method at all. Just create a new instance.
Reflection is your friend. You could create a helper method to use Activator.CreateInstance() to set the default value of Value types and 'null' for reference types, but why bother when setting null on a PropertyInfo's SetValue will do the same.
Type type = this.GetType();
PropertyInfo[] properties = type.GetProperties();
for (int i = 0; i < properties.Length; ++i)
properties[i].SetValue(this, null); //trick that actually defaults value types too.
To extend this for your purpose, have private members:
//key - property name, value - what you want to assign
Dictionary<string, object> _propertyValues= new Dictionary<string, object>();
List<string> _ignorePropertiesToReset = new List<string>(){"foo", "bar"};
Set the values in your constructor:
public Truck() {
PropertyInfo[] properties = type.GetProperties();
//exclude properties you don't want to reset, put the rest in the dictionary
for (int i = 0; i < properties.Length; ++i){
if (!_ignorePropertiesToReset.Contains(properties[i].Name))
_propertyValues.Add(properties[i].Name, properties[i].GetValue(this));
}
}
Reset them later:
public void Reset() {
PropertyInfo[] properties = type.GetProperties();
for (int i = 0; i < properties.Length; ++i){
//if dictionary has property name, use it to set the property
properties[i].SetValue(this, _propertyValues.ContainsKey(properties[i].Name) ? _propertyValues[properties[i].Name] : null);
}
}
Unless creating the object is really expensive (and Reset isn't for some reason). I see no reason to implement a special reset method. Why don't you just create a new instance with a usable default state.
What is the purpose of reusing the instance?
If you did your initialization in a Reset method you can be good to go:
public class Truck {
public string Name;
public int Tires;
public Truck() {
ResetTruck();
}
public void ResetTruck() {
Name = "Super Truck";
Tires = 4;
}
}
Focusing of separation of concerns (like Brian mentioned in the comments), another alternative would be to add a TruckProperties type (you could even add your default values to its constructor):
public class TruckProperties
{
public string Name
{
get;
set;
}
public int Tires
{
get;
set;
}
public TruckProperties()
{
this.Name = "Super Truck";
this.Tires = 4;
}
public TruckProperties(string name, int tires)
{
this.Name = name;
this.Tires = tires;
}
}
Inside your Truck class, all you would do is manage an instance of the TruckProperties type, and let it do its reset.
public class Truck
{
private TruckProperties properties = new TruckProperties();
public Truck()
{
}
public string Name
{
get
{
return this.properties.Name;
}
set
{
this.properties.Name = value;
}
}
public int Tires
{
get
{
return this.properties.Tires;
}
set
{
this.properties.Tires = value;
}
}
public void ResetTruck()
{
this.properties = new TruckProperties();
}
}
This certainly may be a lot of (unwanted) overhead for such a simple class, but in a bigger/more complex project it could be advantageous.
That's the thing about "best" practices... a lot of times, there's no silver bullet, but only recommendations you must take with skepticism and your best judgement as to what applies to you in a particular case.
I solved a similar problem with reflection. You can use source.GetType().GetProperties() to get a list of all properties which belong to the object.
Although, this is not always a complete solution. If your object implements several interfaces, you will also get all those properties with your reflection call.
So I wrote this simple function which gives us more control of which properties we are interested in resetting.
public static void ClearProperties(object source, List<Type> InterfaceList = null, Type SearchType = null)
{
// Set Interfaces[] array size accordingly. (Will be size of our passed InterfaceList, or 1 if InterfaceList is not passed.)
Type[] Interfaces = new Type[InterfaceList == null ? 1 : InterfaceList.Count];
// If our InterfaceList was not set, get all public properties.
if (InterfaceList == null)
Interfaces[0] = source.GetType();
else // Otherwise, get only the public properties from our passed InterfaceList
for (int i = 0; i < InterfaceList.Count; i++)
Interfaces[i] = source.GetType().GetInterface(InterfaceList[i].Name);
IEnumerable<PropertyInfo> propertyList = Enumerable.Empty<PropertyInfo>();
foreach (Type face in Interfaces)
{
if (face != null)
{
// If our SearchType is null, just get all properties that are not already empty
if (SearchType == null)
propertyList = face.GetProperties().Where(prop => prop != null);
else // Otherwise, get all properties that match our SearchType
propertyList = face.GetProperties().Where(prop => prop.PropertyType == SearchType);
// Reset each property
foreach (var property in propertyList)
{
if (property.CanRead && property.CanWrite)
property.SetValue(source, null, new object[] { });
}
}
else
{
// Throw an error or a warning, depends how strict you want to be I guess.
Debug.Log("Warning: Passed interface does not belong to object.");
//throw new Exception("Warning: Passed interface does not belong to object.");
}
}
}
And it's use:
// Clears all properties in object
ClearProperties(Obj);
// Clears all properties in object from MyInterface1 & MyInterface2
ClearProperties(Obj, new List<Type>(){ typeof(MyInterface1), typeof(MyInterface2)});
// Clears all integer properties in object from MyInterface1 & MyInterface2
ClearProperties(Obj, new List<Type>(){ typeof(MyInterface1), typeof(MyInterface2)}, typeof(int));
// Clears all integer properties in object
ClearProperties(Obj,null,typeof(int));
You'd probably need to save the values off in private fields, so that they can be restored later. Maybe something like this:
public class Truck
{
private static const string defaultName = "Super Truck";
private static const int defaultTires = 4;
// Use properties for public members (not public fields)
public string Name { get; set; }
public int Tires { get; set; }
public Truck()
{
Name = defaultName;
Tires = defaultTires;
}
public void ResetTruck()
{
Name = defaultName;
Tires = defaultTires;
}
}
You're essentially looking for the State Design Pattern
If you want a specific past "state" of your object you can create a particular save point to return every time you want. This also let you have a diferent state to backup for everey instance that you create. If you class has many properties who are in constant change, this could be your solution.
public class Truck
{
private string _Name = "Super truck";
private int _Tires = 4;
public string Name
{
get { return _Name; }
set { _Name = value; }
}
public int Tires
{
get { return _Tires; }
set { _Tires = value; }
}
private Truck SavePoint;
public static Truck CreateWithSavePoint(string Name, int Tires)
{
Truck obj = new Truck();
obj.Name = Name;
obj.Tires = Tires;
obj.Save();
return obj;
}
public Truck() { }
public void Save()
{
SavePoint = (Truck)this.MemberwiseClone();
}
public void ResetTruck()
{
Type type = this.GetType();
PropertyInfo[] properties = type.GetProperties();
for (int i = 0; i < properties.Count(); ++i)
properties[i].SetValue(this, properties[i].GetValue(SavePoint));
}
}
If you aren't using a Code Generator or a Designer that would conflict, another option is to go through C#'s TypeDescriptor stuff, which is similar to Reflection, but meant to add more meta information to a class than Reflection could.
using System.ComponentModel;
public class Truck {
// You can use the DefaultValue Attribute for simple primitive properites
[DefaultValue("Super Truck")]
public string Name { get; set; } = "Super Truck";
// You can use a Reset[PropertyName]() method for more complex properties
public int Tires { get; set; } = 4;
public void ResetTires() => Tires = 4;
public Truck() { }
public void ResetTruck() {
// Iterates through each property and tries to reset it
foreach (PropertyDescriptor prop in TypeDescriptor.GetProperties(GetType())) {
if (prop.CanResetValue(this)) prop.ResetValue(this);
}
}
}
Note that ResetValue will also reset to a shadowed property if one exists. The priority of which option is selected is explained in the docs:
This method determines the value to reset the property to in the following order of precedence:
There is a shadowed property for this property.
There is a DefaultValueAttribute for this property.
There is a "ResetMyProperty" method that you have implemented, where "MyProperty" is the name of the property you pass to it.
You may represent an object state as a struct or record struct and then set the state to the default value in the Reset method like this:
public class Truck {
record struct State(string Name, int Tires);
private static readonly State _defaultState = new("Super Truck", 4);
private State _state = _defaultState;
public string Name => _state.Name;
public int Tires => _state.Tires;
public Truck() {}
public void ResetTruck() => _state = _defaultState;
}
It is probably the fastest way as well.
Also, a record struct will give you the trivial implementations of the ToString, Equals, GetHashCode.