WPF调用方法与属性

Question

I'm not very proficient with WPF. What I want to do is bind to a property from my view and then set that value with something. I've got that part working without trouble, but I have a feeling I'm not properly using the MVVM pattern here. I have my property in the ViewModel, bound to the View however I can't seem to get the Model part working as I intend as the method where the property gets its value from is currently also in the ViewModel.

Here's what I currently have:

public class MainViewModel : ViewModelBase
{
    private Awesome _model; //this is my model
    private string _score;

    public string Score
    {
        get { return GetScore(); }
        set
        {
            _score = value;
        }
    }

    public string GetScore()
    {
        try
        {
            using (StreamReader sr = new StreamReader(@"C:\somepath"))
            {
                String line = sr.ReadToEnd();
                return line;
            }
        }
        catch (Exception)
        {
            MessageBox.Show("File could not be found! :(");
            throw;
        }
    }
}

This works fine, but everything is in the ViewModel right now. As far as I understand, GetScore() should be in the Model, but then I'm not sure how to set the property with it. What am I missing here?

Answer 1

The GetScore() -Method should not be in the Model. The model is the data-layer so there are only data-objects with there properties. Methods and other stuff are coordinated by the ViewModel. So you can let your GetScore-Method in your ViewModel or move it to another class and call it from your ViewModel.

By the way: Your property is a little bit weird. becaus in your setter you're setting a backend-field which will never be used again. Are you sure that this is what you want? You should also not always read a file in the getter.

Maybe you want to do something like:

public string Score
{
    get { return _score ?? (_score = GetScore()); }
}

So you only read the file once and keep the value saved in _score.

Answer 2

Your GetScore() belongs to the ViewModel, as it is the data layer. (Of course you could move it to another class, but it's not wrog from my POV in the ViewModel, see it as an extended getter ;))

But

1. You should make GetScore private, because you have a property for it
2. You should not influence the UI from the ViewModel, so I would advise you to not open the MessageBox from the ViewModel.
3. Use return this.GetScore()