I have a class that has a property, and I want to force that this property is of a Type that inherits from a base type
public abstract class BasePropertyClass
{
public string A { get; set;}
}
public class MyPropClass : BasePropertyClass
{
public string B { get; set;}
}
public class MyOtherPropClass : BasePropertyClass
{
public string C { get; set;}
}
public class MyClass
{
public MyPropClass MyPropThatMustInheritBasePropertyClass { get; set;}
}
public class MyOtherClass
{
public MyOtherPropClass MyPropThatMustInheritBasePropertyClass { get; set;}
}
So, how can I make an Interface-ish solution that MyClass and MyOtherClass must have a property MyPropThatMustInheritBasePropertyClass that must have BasePropertyClass as base type
You can make your class generic and add a constraint
public class MyClass<T> where T : BasePropertyClass
{
public T MyPropThatMustInheritBasePropertyClass { get; set;}
}
To better explain #Selman22 answer, you can do something like this:
public abstract class ConstrainedClass<T>
where T: BasePropertyClass
{
public T MyPropThatMustInheritBasePropertyClass { get; set;}
}
In this way, if you declare the other to classes like this:
public class MyClass:ConstrainedClass<MyPropClass>
{
}
public class MyOtherClass:ConstrainedClass<MyOtherPropClass>
{
}
you will obtain the same classes as you declared in your question, plus you have the constraint in the property.
If your classes already inerhits from another class, you need an additional step:
public interface ConstrainedInterface<T>
where T: BasePropertyClass
{
T MyPropThatMustInheritBasePropertyClass { get; set;}
}
and after you must explicitly define the two properties:
public class MyClass : ConstrainedInterface<MyPropClass>
{
public MyPropClass MyPropThatMustInheritBasePropertyClass { get; set;}
}
and
public class MyOtherClass : ConstrainedInterface<MyOtherPropClass>
{
public MyOtherPropClass MyPropThatMustInheritBasePropertyClass { get; set;}
}
You could just use your base type:
public class MyClass
{
public BasePropertyClass Property1 { get; set;}
}
public class MyOtherClass
{
public BasePropertyClass Property2 { get; set;}
}
since both MyPropClass and MyOtherPropClass inherits the same base type, BasePropertyClass.
This way you could assign to either Property1 or Property2 and object of type MyPropClass or MyOtherPropClass.
You can't directly, because the implemented property must be exactly of the type specified in the interface.
Alternative to #Selman's generic solution, you can do so using a backing field:
public interface MyClassInterface
{
BasePropertyClass MyPropThatMustInheritBasePropertyClass { get; set;}
}
public class MyClass : MyClassInterface
{
private MyPropClass _actualProperty;
public BasePropertyClass MyPropThatMustInheritBasePropertyClass
{
get { return _actualProperty; }
set { _actualProperty = (MyPropClass)value; }
}
}
This assumes the not specified requirement "I want to have a member of the derived type in the implementing class", which MyPropClass _actualProperty fulfills.
This will not ensure type safety for the setter, which may throw a cast exception when setting a variable of the wrong type (in this case MyOtherPropClass).
Related
I have a rather simple problem, but I can't find a proper solution anywhere. I would like to specify an abstract object CustomValues as property in my abstract parent class. However, the class inheriting from it should be able to use a more specific type as an object for this property CustomValues. At first I thought I would solve the problem by an interface, but unfortunately that didn't work out either. How do you do something like that, that it works?
public abstract class MyAbstract {
public abstract object CustomValues { get; set; }
}
public class MyImplementation : MyAbstract {
public override MySpecificClass CustomValues { get; set; }
}
This will throw me three errors:
Missing implementation for getter
Missing implementation for setter
Type missmatch between type object and MySpecificClass
The solution suggested in the comments would look something like this. (I'm assuming CustomValues should be a collection of something.)
public class MyClass<T>
{
public ICollection<T> CustomValues { get; set; }
}
Or to ensure CustomValues itself cannot be reassigned, but can be accessed and added to:
public class MyClass<T>
{
public ICollection<T> CustomValues { get; } = new List<T>();
}
I think your original thought that use an interface (+ generic) was at the correct direction. In general you might want to add type constraints as well.
public interface ICustomValues {
....
}
public class MySpecificClass : ICustomValues {
....
}
public abstract class MyAbstract<T> where T : ICustomValues {
public abstract T CustomValues {
get;
set;
}
}
public class MyImplementation: MyAbstract<MySpecificClass> {
public override MySpecificClass CustomValues { get; set; }
}
Thanks to you all guys. I found the solution by using a generic properly:
public abstract class MyAbstract<T> {
public abstract T CustomValues { get; set; }
}
public class MyImplementation : MyAbstract<MySpecificClass> {
public override MySpecificClass CustomValues { get; set; }
}
In my ASP.NET Core API, I have a DTO class BaseDto and another DerivedDto that inherits from BaseDto and hides some of its properties, because they're required in DerivedDto. I also have a BaseModel class to which both BaseDto and DerivedDto will be mapped through another class Mapper.
Something like the following code:
using System.ComponentModel.DataAnnotations;
public class BaseDto
{
public string Name { get; set; }
}
public class DerivedDto : BaseDto
{
[Required]
public new string Name { get; set; }
}
public class BaseModel
{
public string NameModel { get; set; }
}
public static class Mapper
{
public static BaseModel MapToModel(BaseDto dto) => new BaseModel
{
NameModel = dto.Name
};
}
But it turns out, when passing a DerivedDto object to the MapToModel method, it's trying to access the values of the BaseDto (which are null) instead of the DerivedDto ones.
Is there any way I can achieve this behavior?
I can only think of declaring BaseDto as abstract, but that would prevent me from instantiating it, which I need to do.
You need to declare your BaseDto class property as virtual and then override it in the DerivedDto class as follows:
public class BaseDto
{
public virtual string Name { get; set; }
}
public class DerivedDto : BaseDto
{
public override string Name { get; set; }
}
Also, please fix your Mapper class method. There is no property Name in the BaseModel. It needs to be "NameModel = dto.Name"
I have the following scenario:
public class BaseEntity {
public int Id { get; set; }
}
public class BaseAcademicEntity : BaseEntity { ... }
public class BaseFinancialEntity : BaseEntity { ... }
public class Student : BaseAcademicEntity {
public string Name { get; set; }
public Grade CurrentGrade { get; set; }
}
public class Grade : BaseAcademicEntity {
public string Description { get; set; }
}
Ok, now I'll discover the properties from Student class through Reflection.
foreach (PropertyInfo property in typeof(Student).GetProperties()) {
// Here I can discover the type of the current property.
var type = property.PropertyType;
// now, how to discover if this property is from BaseEntity type?
}
Like I wrote in the comment, how to discover if the property is from the BaseEntity type? Thanks!
The simplest way is to use Type.IsAssignableFrom:
if (typeof(BaseEntity).IsAssignableFrom(type))
Once you have a System.Type object, you can iteratively look at the 'BaseType' property until it is null or that it's 'BaseEntity'.
I have a class with 2 interfaces, and I have some superclasses with subclasses, I would like the superclasses to inherit both interfaces. if I just reference the class the interfaces its in, will it work? ie SuperClass : Myinterfaces
here is the class with the interfaces
public class Myinterfaces
{
public interface IBakeable
{
int OvenTemp { get; }
}
public interface IAccounting
{
int Cost { get; }
}
public enum Colors
{
red = 1,
blue,
yellow
}
}
and heres an example of the superclass
public class CeramicsSuperClass : Myinterfaces
{
public string ItemName { get; set; }
public int Cost { get; set; }
public int OvenTemp { get; set; }
}
public class Vases : CeramicsSuperClass
{
private int _BaseDiam;
public Vases(int diam)
{
_BaseDiam = diam;
}
}
You are doing in a wrong way to implement multi-interfaces for a class, try this instead:
public class CeramicsSuperClass : IBakeable, IAccounting {
public string ItemName { get; set; }
public int Cost { get; set; }
public int OvenTemp { get; set; }
}
A class can inherit from only another class but it can implement as many interfaces as possible. When a class inherits from another class and implement some interface, the base class should be listed first, then the interfaces go after like this:
//class A inherits from class B and implements 2 interfaces IC and ID
public class A : B, IC, ID {
//...
}
Simple answer:
You can inherit mulitple interfaces, not multiple classes.
public interface InterfaceA
{
string PropertyA {get;}
}
public interface InterfaceB
{
string PropertyB {get;}
}
public abstract class BaseClassForOthers : InterfaceA, InterfaceB
{
private string PropertyA {get; private set;}
private string PropertyA {get; private set;}
public BaseClassForOthers (string a, string b)
{
PropertyA = a;
PropertyB = b;
}
}
public class SubClass : BaseClassForOthers
{
public SubClass (string a, string b)
: base(a, b)
{
}
}
may be looking here will get you in the general direction (msdn link about interface usage):
http://msdn.microsoft.com/en-us/library/vstudio/ms173156.aspx
When I try to serialize a populated instance of type List<C>() where:
public class A<T> : List<T>
{
[XmlAttribute("Name")]
public string Name {get; set;}
public A() {}
}
public class B
{
[XmlAttribute("Other")]
public string OtherPCO { get; set:}
}
public class C : A<B>
{
}
The serialization drops the Name property of class A but does create an array of type B with the OtherPCO property. How can I get the serializer to include Name?
Collections are serialized in a specific manner, which takes into account only the items of the collection, not the extra properties you added to the class. You need to wrap the collection in another class that is not a collection.
This should give you the desired result :
public class A<T>
{
[XmlAttribute("Name")]
public string Name {get; set;}
[XmlElement(typeof(T))]
public List<T> Items { get; set; }
}