Ndtyjky

Ive been researching and I am a little stuck on finding the right answer.

Lets say I have a c# class with auto properties. I want to have some of these properties calculated based of the properties that a user will change. I understand that you can use a constructor to do this calculation on creation of a new object.

What I am trying to find out is, in a web api does the class constructor get called on an update? Do i do the following or create customer setters?

eg

class myclass 

{

    public int Num1 { get; set; }

    public int Num2 { get; set; }

    public int Num3 { get; set; }

    public int Num4 { get; set; }



    //these get changed when values above get changed by API

    public int result1 { get; set; } 

    public int result2 { get; set; }

    public int result3 { get; set; } 



    //constructor

    public myClass()

    {

        result1 = Num1 + Num2;

        result2 = Num3 + Num2;

        result3 = Num4 + Num2;

    {

}

if I understand correctly, you simply need some derived readonly properties:

class myclass

{

    public myclass()

    {



    }



    public int Num1 { get; set; }

    public int Num2 { get; set; }

    public int Num3 { get; set; }

    public int Num4 { get; set; }





    public int result1 => Num1 + Num2;

    public int result2 => Num3 + Num2;

    public int result3 => Num4 + Num2;



}

What you need to use is INotifyPropertyChanged, see the minimal example below

void Main()

{

    var test = new myClass();

    test.Num1 = 1;

    test.Num2 = 2;

    test.Num3 = 3;

    test.Num4 = 4;



    test.result1.Should().Be(3);

    test.result2.Should().Be(5);

    test.result3.Should().Be(6);



    test.Num1 = 2;

    test.result1.Should().Be(4);

    test.Num2 = 0;

    test.result2.Should().Be(3);

    test.result3.Should().Be(4);

}



class myClass : INotifyPropertyChanged

{

    // private setter since these values are only being set when the num{i} are updated

    public int result1 { get; private set; }

    public int result2 { get; private set; }

    public int result3 { get; private set; }



    public event PropertyChangedEventHandler PropertyChanged;

    public myClass()

    {

        PropertyChanged += new PropertyChangedEventHandler(UpdateResultValue);

    }



    private void UpdateResultValue(object sender, PropertyChangedEventArgs e)

    {

        result1 = num1 + num2;

        result2 = num2 + num3;

        result3 = num2 + num4;

    }



    protected void OnPropertyChanged([CallerMemberName] string propertyName = null)

    {

        PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));

    }



    protected bool SetField<T>(ref T field, T value, [CallerMemberName] string propertyName = null)

    {

        if (EqualityComparer<T>.Default.Equals(field, value)) return false;

        field = value;

        OnPropertyChanged(propertyName);

        return true;

    }



    private int num1;

    public int Num1

    {

        get => num1;

        set => SetField(ref num1, value);

    }



    private int num2;

    public int Num2

    {

        get => num2;

        set => SetField(ref num2, value);

    }



    private int num3;

    public int Num3

    {

        get => num3;

        set => SetField(ref num3, value);

    }



    private int num4;

    public int Num4

    {

        get => num4;

        set => SetField(ref num4, value);

    }

}