Binding a save command WPF

Question

I have a window with 3 textboxes in a grid -this is my view- and I have Save button to add a new user to my user list with the datas from the textboxes. I want to use a relay command to do this on my viewmodel class but I am quite confused with how to make the bindings. I hope it's clear enough. Any ideas, or examples will be helpful. thanks in advance.

Answer 1

You should have a ViewModel something like the following :

class UserViewModel
{
    public String Name { get; set; }
    public String Password { get; set; }
    public String Email { get; set; }

    public RelayCommand AddUserCommand { get; set; }

    public UserViewModel()
    {
        AddUserCommand = new RelayCommand(AddUser);
    }

    void AddUser(object parameter)
    { 
        // Code to add user here.
    }
}

And you can use it like following :

    <StackPanel>
        <TextBox Text="{Binding Name}"></TextBox>
        <TextBox Text="{Binding Password}"></TextBox>
        <TextBox Text="{Binding Email}"></TextBox>
        <Button Command="{Binding AddUserCommand}">Add</Button>
    </StackPanel>

To make this work, put following code in your UserControl/Control/Window's constructor :

DataContext = new UserViewModel();

Answer 2

I presume that you read Josh Smith article: WPF Apps With The Model-View-ViewModel Design Pattern. If you didn't, then read it first, and then download code, because example is very similar to your problem.

Answer 3

Did you created an instance of the ViewModel and putted this instance in the DataContext of your view or stackpanel?

example:

UserViewModel viewModel = new UserViewModel();
UserWindow view = new UserWindow();
view.DataContext = viewModel;
view.Show();

There are several options on coupling the View and the Viewmodel:

• Create the View and ViewModel and set the ViewModel to the DataContext property (code above)
• Create the ViewModel in the constructor of the View and fill the DataContext property with it
• Create a Resource in your view of the type of your ViewModel and fill the DataContext property in XAML

I prefer the first option because you can combine the Views and Viewmodels as you like at runtime.

Hopefully this is a helpfull answer.