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C# how to match generic types from different classes

On one hand I have a list of capabilities, for example:
public interface ICapability
{
public string Name { get; }
}
public class RangeCapability<T> : ICapability
{
public string Name { get; set; }
public T Min { get; set; }
public T Max { get; set; }
}
public class SetCapability<T>
{
public string Name { get; set; }
public HashSet<T> Set { get; set; }
}
On the other hand I have a list of requirements
public interface IRequirement
{
public string Name { get; }
}
public class Requirement<T> : IRequirement
{
public string Name { get; set; }
public T Value { get; set; }
}
Both capability list may contain capabilities of different types T and requirement list may contain requirements of different types. The important thing is that if for a given name the underlying types match I should check if value is between min and max (for range class) or in a set like in the example below:
public class Entity
{
List<ICapability> Capabilities { get; set; }
public bool IsSatisfying(List<IRequirement> requirements)
{
foreach(var requirement in requirements)
{
var capability = Capabilities.FirstOrDefault(x => x.Name == requirement .Name);
//how to check if here if types match and if req. within range or in collection?
}
}
}
I am not sure how to match generic types of two different classes and then do the check suitable for the apropriate implementation (is within range/is present in set). Can somebody point me in the right direction how could I make it work?

I believe this is what you're looking for. Make the interfaces generic and also make the Entity class generic.
public interface INamed<T>
{
string Name { get; }
}
public interface ICapability<T> : INamed<T>
{
}
public class RangeCapability<T> : ICapability<T>
{
public string Name { get; set; }
public T Min { get; set; }
public T Max { get; set; }
}
public class SetCapability<T>
{
public string Name { get; set; }
public HashSet<T> Set { get; set; }
}
public interface IRequirement<T> : INamed<T>
{
}
public class Requirement<T> : IRequirement<T>
{
public string Name { get; set; }
public T Value { get; set; }
}
public class Entity<T>
{
List<ICapability<T>> Capabilities { get; set; }
public bool IsSatisfying(List<IRequirement<T>> requirements)
{
foreach (var requirement in requirements)
{
var capability = Capabilities.FirstOrDefault(x => x.Name == requirement.Name);
//how to check if here if types match and if req. within range or in collection?
if(capability is INamed<T>)
{
Console.WriteLine("types match");
}
}
}
}

Struggling with the C# generics, is this possible?

I'm currently on design stage in writing C# .NET Core application. I'm gonna use the generics to inherit some properties among all derived classes. The goal is to archive many 2 many relation of entities able to be tagged. The app concept is funky, because tag will contain related logic as constraint entity. I have problems with the proper where statements in generic class, to be able to use inherited Tags property for all Taggable Entities.
Here is abstraction:
public interface ITaggable
{
long TagId { get; set; }
Tag Tag { get; set; }
}
public interface IEntityTag<T> : ITaggable where T : Entity
{
long EntityId { get; set; }
T Entity { get; set; }
}
public abstract class TaggableEntity<T> : Entity where T : ITaggable
{
public ICollection<T> EntityTags { get; set; }
public List<Tag> Tags { get { return EntityTags.Select(x => x.Tag).ToList(); } }
}
public abstract class ConstraintBase<TSubject, TOwner>
: ConstraintEntity where TOwner : TaggableEntity<IEntityTag<TOwner>>
{
protected ConstraintBase(ConstraintId id, string description)
{
Id = id.Value();
Name = id.ToString();
Description = description;
IsExecutable = false;
}
public IEnumerable<TSubject> Validate(IEnumerable<TSubject> items, TOwner owner)
{
return items.Where(x => Validate(x, owner));
}
public void Execute()
{
if (IsExecutable) { OnExecuting(); }
}
protected abstract bool Validate(TSubject item, TOwner owner);
public abstract void OnExecuting();
}
And here concrete classes.
public class ConstraintEntity : Entity
{
public string Name { get; set; }
public string Description { get; set; }
public bool IsExecutable { get; set; }
public ConstraintId ConstraintId => (ConstraintId)Id;
}
public class EndWorkConstraint : ConstraintBase<Activity, User>
{
public EndWorkConstraint() : base(ConstraintId.EndWorkConstraint, "Check if user is allowed to end work")
{
}
protected override bool Validate(Activity item, User owner)
{
return item.ActivityId != ActivityId.EndWork;
}
public override void OnExecuting()
{
throw new System.NotImplementedException();
}
}
public class User : TaggableEntity<UserTag>
{
public string Login { get; set; }
public string Password { get; set; }
}
The question is: am I able to modify ConstraintBase where statement, to make EndWorkConstraint class do not raising an error, and still have the tags explicit avalible?
This is my first post on the forum, and I m really forced to use Yours wisdom. I'd be glad for any tips. Thanks in advance.

C#. Universal desition for storing different types

I'm looking for the best approach of working with different types identically.
I have a web service that goes to specific resource, makes some research and returns an object WebResult, that contains all information about completed operations.
And now I'd like to build a set of different metrics, that will describe all received results. These metrics should provide
different types of data
easy way to collect it
possibility to deserialize it.
Example 1
First I've created separate classes for different metrics
public abstract class AbstractStatistic
{
public string Url { get; set; }
public string ExceptionMessage { get; set; }
public abstract void FillAllMetrics(WebResult result);
}
public class Resource1Statistic : AbstractStatistic
{
public string Title { get; set; }
public string[] Table1_Header { get; set; }
public int Table1_RowCount { get; set; }
public string[] Table2_Header { get; set; }
public int Table2_RowCount { get; set; }
public override void FillAllMetrics(WebResult result)
{
this.Url = result.url;
this.Title = result.data["title"];
this.Table1_Header = result.data["table1.header"].ToObject<string[]>();
//...
}
}
It works, but I'd like to make it in more standard way. One of the reason is that in this approach I have to create separate web form for each metrics.
Example 2
Second working example is universal but redundant: create an abstraction of any datatype
public abstract class AbstractStatistic
{
public string Url { get; set; }
public string Exception { get; set; }
public Dictionary<string, Metric> Metrics { get ;set;}
public abstract void FillAllMetrics(WebResult webResult);
}
public class Metric // Specific class for data
{
public string StringValue { get; set; }
public int? IntegerValue { get; set; }
public string[] ArrayValue { get; set; }
public DateTime? DateTimeValue { get; set; }
}
public class Resource1Statistic : AbstractStatistic
{
public override void FillAllMetrics(WebResult result)
{
this.Metrics.Add("title",
new Metric() { StringValue = result.data["title"].ToString() });
this.Metrics.Add("Table1 Header",
new Metric() { ArrayValue = result.data["table1.header"].ToObject<string[]>() });
//...
}
It works, but I'm sure there is more elegant solution. I don't like to take all these null values in json.
Examples 3
Generic solution (regarding to Adwaenyth)
public abstract class AbstractStatistic
{
public string Url { get; set; }
public string Exception { get; set; }
public List<AbstractMetric> Metrics { get ;set;}
public abstract void FillAllMetrics(WebResult webResult);
}
public abstract class AbstractMetric{}
public class Metric<T> : AbstractMetric
{
public string Name { get; set; }
public T Value { get; set; }
public string Type { get; private set; }
public Metric()
{
this.Type = typeof(T).ToString();
}
}
public class Resource1Statistic : AbstractStatistic
{
public override void FillAllMetrics(WebResult result)
{
this.Metrics.Add(new Metric<string>()
{ Name = "title",
Value = result.data["title"].ToString() });
this.Metrics.Add(new Metric<string[]>()
{ Name = "Table1 Header",
Value = result.data["table1.header"].ToObject<string[]>() });
//...
}
This solution looks nice, but I have to write custom deserializer.
What do you think, is there some good pattern that fits to my task? Or what's the best approach?

How do I organize C# classes that inherit from one another, but also have properties that inherit from one another?

I have an application that has a concept of a Venue, a place where events happen. A Venue has many VenueParts. So, it looks like this:
public abstract class Venue
{
public int Id { get; set; }
public string Name { get; set; }
public virtual ICollection<VenuePart> VenueParts { get; set; }
}
A Venue can be a GolfCourseVenue, which is a Venue that has a Slope and a specific kind of VenuePart called a HoleVenuePart:
public class GolfCourseVenue : Venue
{
public string Slope { get; set; }
public virtual ICollection<HoleVenuePart> Holes { get; set; }
}
In the future, there may also be other kinds of Venues that all inherit from Venue. They might add their own fields, and will always have VenueParts of their own specific type.
Here are the VenuePart classes:
public abstract class VenuePart
{
public int Id { get; set; }
public string Name { get; set; }
public abstract string NameDescriptor { get; }
}
public class HoleVenuePart : VenuePart
{
public override string NameDescriptor { get { return "Hole"; } }
public int Yardage { get; set; }
}
My declarations above seem wrong, because now I have a GolfCourseVenue with two collections, when really it should just have the one. I can't override it, because the type is different, right? When I run reports, I would like to refer to the classes generically, where I just spit out Venues and VenueParts. But, when I render forms and such, I would like to be specific.
I have a lot of relationships like this and am wondering what I am doing wrong. For example, I have an Order that has OrderItems, but also specific kinds of Orders that have specific kinds of OrderItems.
Update: I should note that these classes are Entity Framework Code-First entities. I was hoping this wouldn't matter, but I guess it might. I need to structure the classes in a way that Code-First can properly create tables. It doesn't look like Code-First can handle generics. Sorry this implementation detail is getting in the way of an elegant solution :/
Update 2: Someone linked to a search that pointed at Covariance and Contravariance, which seemed to be a way to constrain lists within subtypes to be of a given subtype themselves. That seems really promising, but the person deleted their answer! Does anyone have any information on how I may leverage these concepts?
Update 3: Removed the navigation properties that were in child objects, because it was confusing people and not helping to describe the problem.

Here's one possible option using generics:
public abstract class VenuePart
{
public abstract string NameDescriptor { get; }
}
public class HoleVenuePart : VenuePart
{
public string NameDescriptor { get{return "I'm a hole venue"; } }
}
public class Venue<T> where T : VenuePart
{
public int Id { get; set; }
public string Name { get; set; }
public virtual Company Company { get; set; }
public virtual ICollection<T> VenueParts { get; set; }
}
public class GolfCourseVenue : Venue<HoleVenuePart>
{
}
Here GolfCourseVenue has the collection VenueParts, which can contain HoleVenueParts or super classes HoleVenueParts. Other specializations of Venue would restrict VenueParts to containing VenueParts specific to that venue.
A second possibility is pretty much as you had it
public abstract class VenuePart
{
public abstract string NameDescriptor { get; }
}
public class HoleVenuePart : VenuePart
{
public string NameDescriptor { get{return "I'm a hole venue"; } }
}
public class Venue
{
public int Id { get; set; }
public string Name { get; set; }
public virtual Company Company { get; set; }
public virtual ICollection<VenuePart> VenueParts { get; set; }
}
public class GolfCourseVenue : Venue
{
}
Now GolfCourseVenue has the collection VenueParts, which can contain VenueParts or super classes VenueParts. Here all specializations of Venue can contain any type of VenuePart which may or may not be appropriate.
In answer to your comment about covariance, I would propose something like this:
public abstract class VenuePart
{
public abstract string NameDescriptor { get; }
}
public class HoleVenuePart : VenuePart
{
public override string NameDescriptor { get{return "I'm a hole venue"; } }
}
public abstract class Venue
{
public int Id { get; set; }
public string Name { get; set; }
public abstract ICollection<VenuePart> VenueParts { get; }
}
public class GolfCourseVenue : Venue
{
private ICollection<HoleVenuePart> _holeVenueParts;
public GolfCourseVenue(ICollection<HoleVenuePart> parts)
{
_holeVenueParts = parts;
}
public override ICollection<VenuePart> VenueParts
{
get
{
// Here we need to prevent clients adding
// new VenuePart to the VenueParts collection.
// They have to use Add(HoleVenuePart part).
// Unfortunately only interfaces are covariant not types.
return new ReadOnlyCollection<VenuePart>(
_holeVenueParts.OfType<VenuePart>().ToList());
}
}
public void Add(HoleVenuePart part) { _holeVenueParts.Add(part); }
}

I look forward to the advice of others - but my approach is to use generics in this case. With generics, your GolfCourseVenue's "parts" are strong typed!
...and as I type this everyone else is saying generics too. HOW DO YOU overstackers type so dang fast?!
Anyways, pretending I'm still first -
public class VenuePart
{
}
public class HoleVenuePart : VenuePart
{
}
public abstract class Venue<T> where T : VenuePart
{
public int Id { get; set; }
public string Name { get; set; }
public virtual Company Company { get; set; }
public virtual ICollection<T> Parts { get; set; }
}
public class GolfCourseVenue : Venue<HoleVenuePart>
{
public string Slope { get; set; }
}
Also, as a 2nd option, you could use an interface too, so in case you didn't like the name Parts, you could call it Holes when the derived type is known to be a GolfCourse
public class VenuePart
{
}
public class HoleVenuePart : VenuePart
{
}
public interface IPartCollection<T> where T : VenuePart
{
ICollection<T> Parts { get; set; }
}
public abstract class Venue<T> : IPartCollection<T> where T : VenuePart
{
public int Id { get; set; }
public string Name { get; set; }
public virtual Company Company { get; set; }
public virtual ICollection<T> Parts { get; set; }
}
public class GolfCourseVenue : Venue<HoleVenuePart>
{
public string Slope { get; set; }
ICollection<HoleVenuePart> IPartCollection<HoleVenuePart>.Parts { get { return base.Parts; } set { base.Parts = value; }}
public virtual ICollection<HoleVenuePart> Holes { get { return base.Parts; } set { base.Parts = value;}}
}

You can use Covariance
public abstract class Venue
{
public int Id { get; set; }
public string Name { get; set; }
public virtual Company Company { get; set; }
public virtual IEnumerable<VenuePart> VenueParts { get; set; }
}
public class GolfCourseVenue : Venue
{
public string Slope { get; set; }
public GolfCourseVenue()
{
List<HoleVenuePart> HoleVenueParts = new List<HoleVenuePart>();
HoleVenueParts.Add(new HoleVenuePart());
VenueParts = HoleVenueParts;
}
}
Assuming HoleVenuePart is inherited from VenuePart

If you remove "set" portions of both collections than it will make more sense: base class provides "all parts" collection, while derived classes have filtered view in addition to base class one.
Note: Depending on your needs making GolfVenue to be specialization generic of Venue<VenuePart> may not work as Venue<Type1> and Venue<Type2> will not have any good base class to work with.
Consider using interfaces instead of base classes as it would allow more flexibility in implementation.
public interface IVenue
{
public int Id { get; }
public string Name { get; }
public virtual IEnumerabe<VenuePart> VenueParts { get; }
}
public interface IGolfCourse : IVenue
{
public virtual IEnumerabe<HoleVenuePart> Holes { get; }
}
Now you can use GolfCourse:Venue from other samples but since it implements interface you can handle it in gnereic way too:
class GolfCourse:Venue<HoleVenuePart>, IGolfCourse {
public virtual IEnumerabe<VenuePart> Holes{ get
{
return VenueParts.OfType<HoleVenuePart>();
}
}
}
class OtherPlace:Venue<VenuePart>, IVenue {...}
List<IVenue> = new List<IVenue> { new GolfCourse(), new OtherPlace() };
Nothe that GolfCourse and OtherPlace don't have common parent class (except object), so without interface you can't use them interchangebly.

Generic parameter problem

I have a business model which consists of a parent/child relationship (Identifier/IdentifierValue) and also some snapshot classes which look the same (IdentifierSnapshot/IdentifierValueSnapshot).
I am trying to create an extension method which will work on an enumeration of either Identifier or IdentifierSnapshot, but I just can't work out what to put in the extension method where I have inserted the XXX placeholder.
//Interfaces
public interface IIdentifier<TIdentifierValue>
where TIdentifierValue : IIdentifierValue
{
string Code { get; }
IEnumerable<TIdentifierValue> GetValues();
}
public interface IIdentifierValue
{
string Code { get; }
string Value { get; }
}
//Main classes
public class Identifier : IIdentifier<IdentifierValue>
{
public string Code { get; set; }
public IEnumerable<IdentifierValue> GetValues();
}
public class IdentifierValue : IIdentifierValue
{
public string Code { get; set; }
public string Value { get; set; }
}
//Snapshots
public class IdentifierSnapshot : IIdentifier<IdentifierValueSnapshot>
{
public string Code { get; set; }
public IEnumerable<IdentifierValueSnapshot> GetValues();
}
public class IdentifierValueSnapshot : IIdentifierValue
{
public string Code { get; set; }
public string Value { get; set; }
}
public static IdentifierExtensions
{
public static IEnumerable<XXX> ByCode<XXX>(this IEnumerable<XXX> instance, string code)
{
return instance.Where(x => string.Compare(code, x.Code, true) == 0);
}
}

I think this would do it:
public static IEnumerable<T> ByCode<T,Z>(this IEnumerable<T> instance, string code)
where T:IIdentifier<Z>
where Z:IIdentifierValue