So i have two different objects, with different properties:
public class ModelA : IServices
{
public string Id { get; set; }
public ServiceType ServiceType { get; set; } (Enum)
public DateTime StartDate { get; set; }
public DateTime EndDate { get; set; }
public int Limit { get; set; }
public int ChargePower { get; set; }
}
public class ModelB : IServices
{
public string Id { get; set; }
public ServiceType ServiceType { get; set; } (Enum)
public DateTime StartDate { get; set; }
public DateTime EndDate { get; set; }
public int Power { get; set; }
}
I have then created an Interface:
public interface IServices
{
public string Id { get; set; }
public ServiceType ServiceType { get; set; }
public DateTime StartDate { get; set; }
public DateTime EndDate { get; set; }
}
And i then use this interface as a input parameter on my method:
public async Task EditObject(IServices serviceObject)
{
}
My problem now is that if i call the method with e.g ModelA, i can only use the properties that is inside my Interface, and yes that makes sense.
How can i make a method that can take both ModelA and ModelB and access the different properties inside these two objects?
Is generics the way to go? or do i have to make two different methods? or am i on the correct way with an Interface?
For instance i dont want ModelA to have ModelB:s property e.g "public int Power { get; set; }"
Hope you understand my question, cheers!
You can test, which class is it:
if (serviceObject is ModelA)
((ModelA)serviceObject).Limit = 5;
Or you can use Reflection:
PropertyInfo pi;
if ((pi = x.GetType().GetProperty("Limit")) != null)
pi.SetValue(x, 5);
Well, a lot of ways
You can make a method overload
public async Task EditObject(ModelA serviceObject) { }
public async Task EditObject(ModelB serviceObject) { }
or you could access needed type through upcasting it
var iServiceVariable = (IServices)new ModelA();
var modelBVariable = iServiceVariable as ModelB;
Console.WriteLine($"Is iServiceVariable of ModelB type? {modelBVariable != null}");
Or you could implement different behavior in your models using the same interface(doesn't have to be IServices), but accessing them in EditObject through the same way (what's the point of interface otherwise?)
If you want to do different things for multiple types, a fairly clean way to do it is by using a switch on the type:
switch(serviceObject)
{
case ModelA modelA:
modelA.Limit = 5;
break;
case ModelB modelB:
modelB.Power = 2;
break;
}
Related
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");
}
}
}
}
This is my first question on StackOverflow, so please forgive and tell me if I'm doing something wrong.
Problem:
I write some kind of dictionary connected to DB and text files etc. nothing commercial, just learning. For better explanation it can be English-French.
I want to refactor the code to have possibility of use one "general" method to process entrance for English-French and French-English dictionary model. On the begining i made separate model for each of them(I will paste if necessary) and now i would like to make everything "universal". What I did till i stop:
public interface IWordModel
{
int Id { get; set; }
string Name { get; set; }
string Definition { get; set; }
}
class implementing IWordModel:
public class EnglishWordModel: IWordModel
{
public int Id { get; set; }
public string Name { get; set; }
public string Definition { get; set; } = null;
}
public class FrenchWordModel : IWordModel
{
public int Id { get; set; }
public string Name { get; set; }
public string Definition { get; set; } = null;
}
Interface implementing IWordModel and problematic List of this interface:
public interface IDictionairyModel<T> where T : IWordModel
{
int Id { get; set; }
T BaseWord { get; set; }
List<T> DerivativeWords { get; set; }
}
Class implementing IDicionairyModel
public class EnglishFrenchDictionairyModel<T>: IDictionairyModel where T : IWordModel
{
public int Id { get; set; }
public IWordModel BaseWord { get; set; } = new EnglishWordModel();
public List<IWordModel> DerivativeWords { get; set; } = = new
List<IWordModel>(new List<FrenchWordModel>());
}
public class FrenchDictionairyModel: IDictionairyModel<T> where T : IWordModel
{
public int Id { get; set; }
public IWordModel BaseWord { get; set; } = new FrenchWordModel();
public List<IWordModel> DerivativeWords { get; set; } = = new
List<IWordModel>(new List<EnglishWordModel>());
}
And my Question
How to make that i.e in FrenchDictionairyModel instance we will be able to define BaseWord only as FrenchWordModel and add to DerivativeWords list ONLY EnglishWordModel? I know it have something common with covariance and contrvariance but i dont have idea how to apply this here.
Is it above code have some sense from experienced coder point of view or it's look like OK only in my head? If answer is NO then how it should look like, what pattern should i use?
How to use it properly in other methods? As now i was using i.e
public List<EnglishFrenchDictionairyModel>
CreateEnglishFrenchEntrance(List<EnglishFrenchDictionairyModel> model){
( ... )}
but its already showing "Using generic type requires 1 type arguments".
Thanks and have a Great Day!
It sounds like you need two generic parameters - one to apply to BaseWord and one to apply to DerivativeWords:
public interface IDictionairyModel<T,U>
where T : IWordModel, U : IWordModel
{
int Id { get; set; }
T BaseWord { get; set; }
List<U> DerivativeWords { get; set; }
}
Then define your FrenchDictionaryModel as so:
public class FrenchDictionairyModel:
IDictionairyModel<FrenchWordModel, EnglishWordModel>
{
public int Id { get; set; }
public FrenchWordModel BaseWord { get; set; } = new FrenchWordModel();
public List<EnglishWordModel> DerivativeWords { get; set; } = new List<EnglishWordModel>();
}
Thanks D Stanley! it works fine, just need to add two where clauses for U and T like:
public interface IDictionairyModel<T,U>
where T : IWordModel,
where U : IWordModel {(...)}
But now i have another issue which i would like to implement here.
For example i would like to create some method which will be remove duplicates from List but i want to this to be ONE method for all class which implementing IDictionairyModel
public static List<IDictionairyModel<IWordModel, IWordModel>> RemoveDuplicates(this List<IDictionairyModel<IWordModel, IWordModel>> model)
{
(...) return model;
}
What I need to do to be able to use this extension method on
List<FrenchDictionairyModel> model = new List<FrenchDictionairymodel>();
model.RemoveDuplicates();
As for now it return error.
Should I make FrenchDictionairyModel also generic like:
public class PoznanPolishDictionairyModel<T,U> : IDictionairyModel<PoznanWordModel, PolishWordModel>
where T:IWordModel
where U:IWordModel
??? What is the proper way
Thanks a lot!!!
Have a wonderful Sunday!
Best Regards
First of all I'm new to C#.
The error I get is:
Additional information: Unable to cast object of type 'UserGUI.MyItems' to type 'CommonBookLib.AbstractItem'.
They are 2 different classes:
public class MyItems
{
public string ItemName { get; set; }
public int CopyNumber { get; set; }
public int Guid { get; set; }
public DateTime? TimePrinted { get; set; }
public string Category { get; set; }
public string SubCategory { get; set; }
public bool? BestSeller { get; set; }
}
and
public class AbstractItem : IPropsDetails
{
public int CopyNumber { get; }
public string ItemName { get; }
public DateTime Time { get; }
public int Guid { get; }
public AbstractItem(int copyNumber, string itemName, DateTime time, int guid)
{
this.CopyNumber = copyNumber;
this.ItemName = itemName;
this.Time = time;
this.Guid = guid;
}
}
It happens when I do:
AbstractItem myItemsList = (AbstractItem)LibraryList.SelectedItem;
logicManager.Remove(myItemsList);
Well, as you can see, I have MyItems which are responsible for the DataBindings in my GUI and AbstractItem which responsible for implementing an addition operation to where my data is saved.
Since I did not managed my code well I got into this situation and I really do not want to change MyItems (delete and recode AbstractItem).
How can I Convert the two?
By the way, I know AbstractItem has only 4 properties while MyItems has more.
However, I have children with the exact same properties of AbstractItem.
Any help would be appreciated. Thanks in advance!
Remove fields from the MyItems class that are also present in AbstractItem, and then have MyItems derive from it instead.
You'll have to add a constructor to MyItems that passes the required values to the base constructor, or add an empty constructor to the base class.
public class MyItems : AbstractItem
{
public MyItems(int copyNumber, string itemName, DateTime time, int guid)
:base(copyNumber, itemName, time, guid)
{
}
public DateTime? TimePrinted { get; set; }
public string Category { get; set; }
public string SubCategory { get; set; }
public bool? BestSeller { get; set; }
}
You can make MyItems inherit AbstractItem, or make a method that handle the conversion between them.
You seem to need a mapper more than a cast. Look at AutoMapper or write your own routine as suggested by habibhassani. Also, Grant's answer is very good.
But your question was about casting so here I show how you can implement a casting operator so that your cast would work. This is not a technique you should reach for lightly. It puts a dependency on AbstractItem directly in MyItems and it is not the most discoverable pattern for maintainers of your code.
public class MyItems
{
public string ItemName { get; set; }
public int CopyNumber { get; set; }
public int Guid { get; set; }
public DateTime? TimePrinted { get; set; }
public string Category { get; set; }
public string SubCategory { get; set; }
public bool? BestSeller { get; set; }
public static explicit operator AbstractItem(MyItems myitems)
{
return new AbstractItem(myitems.CopyNumber, myitems.ItemName, myitems.TimePrinted, myitems.Guid);
}
}
A couple more observances. Naming your class AbstractItem is confusing, it implies that it is actually abstract but it is not.
Guid is a poor name for a property because it is already a Type. You have something named Guid that is an int - confusing.
I have a number of classes that are all related conceptually, but some more-so at the details level than others. For example, these three classes have nearly identical properties (although member functions will vary):
public class RelatedA : IRelatedType
{
public string Name { get; set; }
public string Value { get; set; }
public DateTime Stamp { get; set; }
}
public class RelatedB : IRelatedType
{
public string Name { get; set; }
public string Value { get; set; }
public DateTime Stamp { get; set; }
}
public class RelatedC : IRelatedType
{
public string Name { get; set; }
public string Value { get; set; }
public DateTime Stamp { get; set; }
public int Special { get; set; }
}
There are a couple of other classes that are conceptually related to the above 3, but can be a bit different implementation-wise:
public class RelatedD : IRelatedType
{
public string Name { get; set; }
public string Statement { get; set; }
}
public class RelatedE : IRelatedType
{
public string Name { get; set; }
public string Statement { get; set; }
public bool IsNew { get; set; }
}
Instances of these can be created by a factory based on some sort of "type" enumerated value. The problem is that later on when these objects are being used (in a business layer, for example), there could be a lot of code like this:
IRelatedType theObject = TheFactory.CreateObject(SomeEnum.SomeValue);
if (theObject is RelatedC)
{
RelatedC cObject = theObject as RelatedC;
specialVal = cObject.Special;
}
else if (theObject is RelatedD)
{
RelatedD dObject = theObject as RelatedD;
statementVal = dObject.Statement;
}
else if (theObject is RelatedE)
{
RelatedE eObject = theObject as RelatedE;
statementVal = eObject.Statement;
isNewVal = eObject.IsNew;
}
This could be repeated in many places. Is there a better approach to the design that I should be using (there's got to be)?
You could try and factor the differences into seperate classes that are then provided so for example:
IRelatedType theObject = TheFactory.CreateObject(SomeEnum.SomeValue);
RelatedTypeHelper theHelper=TheFactory.CreateHelper(theObject);
theHelper.DoSpecialThing(theObject);
Now you won't have to have all the if else blocks, and if you add a new type which requires new handling, you just whip up a new helper implement the required pieces and you should be good to go. The helper should help document this process.
I would also question why a single method would have such a different implementation for specialVal and StatementVal could be your sample, but It makes me curious what your really doing here. can you simplify things back taking a step back and questioning the point of these being included in this specific hierarchy.
I am creating a drivers license object in my project, that employees will all have one of their own linked to their unique clock number. I have a separate table in my database for the driving license but in the future more types of vehicles will need to be added, is there anyway to do this without re-coding?
the columns in my database are the same as the attributes for the class below
public class LicenseDTO
{
public int ClockNo { get; set; }
public bool CBalance { get; set; }
public bool MR16 { get; set; }
public bool OrderPicker { get; set; }
public bool Reach { get; set; }
public bool Pedestrian { get; set; }
public bool Lorry { get; set; }
public bool Sweeper { get; set; }
public bool Washer { get; set; }
}
EDIT
I have tried to create this the best I could but I feel like it's really long winded and can be done a more efficient way. Here's an updated version of my code.
public class LicenseDTO
{
public int ClockNo { get; set; }
public List<Common.VehicleTypeDTO> Vehicles { get; set; }
}
public class VehicleTypeDTO
{
public string VehicleType { get; set; }
public bool Allowed { get; set; }
}
private void btnClockCardIn_Click(object sender, EventArgs e)
{
Common.LicenseDTO License = new Common.LicenseDTO();
List<Common.VehicleTypeDTO> Vehicles = new List<Common.VehicleTypeDTO>();
Common.VehicleTypeDTO CBalance = new Common.VehicleTypeDTO();
Common.VehicleTypeDTO MR16 = new Common.VehicleTypeDTO();
License.Vehicles = Vehicles;
CBalance.VehicleType = "CBalance";
CBalance.Allowed = true;
MR16.VehicleType = "MR16";
MR16.Allowed = false;
License.Vehicles.Add(CBalance);
License.Vehicles.Add(MR16);
foreach (Common.VehicleTypeDTO Vehicle in License.Vehicles)
{
MessageBox.Show(Vehicle.VehicleType + " " + Vehicle.Allowed);
}
}
Why not to create a table with the types of vehicles? In the future you can access to your table and insert more types.
public class VehicleTypeDTO
{
public int Id{ get; set; }
public string Name{ get; set; }
}
public class LicenseDTO
{
public int Id { get; set; }
public List<VehicleTypeDTO> VehicleTypes { get; set; }
}
You should have made an entity LicenseDTO with the attributes ClockNo and CBalance alongside an array of the type Vehicle. which will be an interface. the interface Vehicle can define any common methods the vehicles have. and all future vehicles will have to implement the interface. that way you dont have to change any code. Your current code cannot be "changed" without editing. You could try to extend your LicenseDTO class with another entityclass which implements the above interface. but there isnt much more you can do without editing.
If you want maintainability use interfaces, repository patterns, abstract classes and dependency injection to start with.
Instead of having multiple bit columns in your database to indicate different types of vehicles, have a single VehicleType table. Then you can add as many different vehicle types as you like and use the VehicleTypeID to uniquely identify them. You can then add more and more vehicle types to the table without having to write more code.
VehicleType
VehicleTypeID int
VehicleTypeName varchar(50)
public class LicenseDTO
{
public int ClockNo { get; set; }
public int VehicleTypeID { get; set; }
}
If you want to have multiple types of vehicles against a single ClockNo then use a list of int:
public class LicenseDTO
{
public int ClockNo { get; set; }
public List<int> VehicleTypes { get; set; }
}
Alternately you could have a reference to the VehicleType objects instead of just the ID's.