C#•3y ago

✅ Generic nullable type

I have an interface

ITypelyValue<TValue, TTypelyValue>

ITypelyValue<TValue, TTypelyValue>

ITypelyValue<TValue, TTypelyValue>

ITypelyValue<TValue, TTypelyValue> that let me create validated value objects.

I need to convert theses types using a ValueConverter for EF Core.

public class TypelyValueConverter<TValue, TTypelyValue> : ValueConverter<TTypelyValue, TValue>
    where TTypelyValue : ITypelyValue<TValue, TTypelyValue>
{
    public TypelyValueConverter()
        : base(
            v => v.Value,
            v => TypelyValue.From<TValue, TTypelyValue>(v))
    {
    }
}

public class TypelyValueConverter<TValue, TTypelyValue> : ValueConverter<TTypelyValue, TValue>
    where TTypelyValue : ITypelyValue<TValue, TTypelyValue>
{
    public TypelyValueConverter()
        : base(
            v => v.Value,
            v => TypelyValue.From<TValue, TTypelyValue>(v))
    {
    }
}

public class TypelyValueConverter<TValue, TTypelyValue> : ValueConverter<TTypelyValue, TValue>
    where TTypelyValue : ITypelyValue<TValue, TTypelyValue>
{
    public TypelyValueConverter()
        : base(
            v => v.Value,
            v => TypelyValue.From<TValue, TTypelyValue>(v))
    {
    }
}

public class TypelyValueConverter<TValue, TTypelyValue> : ValueConverter<TTypelyValue, TValue>
    where TTypelyValue : ITypelyValue<TValue, TTypelyValue>
{
    public TypelyValueConverter()
        : base(
            v => v.Value,
            v => TypelyValue.From<TValue, TTypelyValue>(v))
    {
    }
}

This works fine for value types. e.g.

public struct MyValueObject : ITypelyValue<int, MyValueObject>{...}

public struct MyValueObject : ITypelyValue<int, MyValueObject>{...}

public struct MyValueObject : ITypelyValue<int, MyValueObject>{...}

public struct MyValueObject : ITypelyValue<int, MyValueObject>{...}.
With an entity :

public class MyEntity
{
    public MyValueObject Prop1 {get; set;}  //ok
    public MyValueObject? Prop2 {get; set;}  //Error
}

public class MyEntity
{
    public MyValueObject Prop1 {get; set;}  //ok
    public MyValueObject? Prop2 {get; set;}  //Error
}

public class MyEntity
{
    public MyValueObject Prop1 {get; set;}  //ok
    public MyValueObject? Prop2 {get; set;}  //Error
}

public class MyEntity
{
    public MyValueObject Prop1 {get; set;}  //ok
    public MyValueObject? Prop2 {get; set;}  //Error
}

When I make my value object nullable, the property becomes a reference type and I'm confused of how I can handle saving a null value to the database with the type converter.

Other ref: https://github.com/adampaquette/Typely/blob/main/src/Typely.Core/ITypelyValue.cs

GitHub

Typely/ITypelyValue.cs at main · adampaquette/Typely

Typely lets you create types easily with a fluent API to embrace Domain-driven design and value objects. - Typely/ITypelyValue.cs at main · adampaquette/Typely

✅ Generic nullable type

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