如果值在另一类中更改，则如何在一个类中更改值

Question

Let's say I have a parameter in my ViewModel:

public string ChosenQualityParameter
{
     get => DefectModel.SelectedQualDefectParameters?.Name ?? "Не выбран параметр";
}

and I have a class DefectModel with parameter SelectedQualDefectParameters.Name in it. I want to change the UI binded to ChosenQualityParameter , when the Name parameter changes too. But I don't know how to do this properly. Any suggestions? Thanks in advance.

Answer 1

You might define your ViewModel class like this:

public class ViewModel
{
    private DefectModel _defectModel;

    public ViewModel(DefectModel defectModel)
    {
        _defectModel = defectModel;
    }

    public string ChosenQualityParameter
    {
        get => _defectModel.SelectedQualDefectParameters?.Name ?? "Не выбран параметр";
    }
}

I personally do not like such dependencies in viewmodels, but it might get the job done here. It seems to work in a console application anyway:

using System;

public class Parameters
{
    public string Name { get; set; }
}

public class DefectModel
{
    public Parameters SelectedQualDefectParameters { get; set; }
}

public class ViewModel
{
    private DefectModel _defectModel;

    public ViewModel(DefectModel defectModel)
    {
        _defectModel = defectModel;
    }

    public string ChosenQualityParameter
    {
        get => _defectModel.SelectedQualDefectParameters?.Name ?? "Не выбран параметр";
    }
}

class Program
{
    static void Main()
    {
        var defectModel = new DefectModel
        {
            SelectedQualDefectParameters = new Parameters
            {
                Name = "test"
            }
        };

        var viewModel = new ViewModel(defectModel);

        Console.WriteLine(viewModel.ChosenQualityParameter);

        defectModel.SelectedQualDefectParameters.Name = "changed";

        Console.WriteLine(viewModel.ChosenQualityParameter);

        Console.ReadKey();
    }
}

Answer 2

Thanks to @Knoop and @BartHofland, I've solved my issue by using INotifyPropertyChanged in my DefectModel and SelectedQualDefectParameters classes. For setting ChosenQualityParameter I used MessagingCenter to send new value.