CODEWITHSUNDEEP
c#mvvmxamarin.formsvisual-studio-2017
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Reputation: 3301

Practical example of MVVM for Xamarin.Forms?

Ever since I began learning about Xamarin.Forms, I've read that MVVM is the preferred architecture for this. This is all new to me, so please be patient.

At work, a typical application (either asp.net or Windows Forms) will include an event handler that calls a method and displays it into a UI control:

private void buttonShow_Click(object sender, EventArgs e)
{
    Vendors.Sales carSales = new Vendors.Sales();
    DataTable carsTable = carSales.SalesMade();
    DatagridSales.datasource = carsTable;
}

carSales.SalesMade is a method that exists somewhere that returns a list that I display in my UI. I don't know what carSales.SalesMade is; I just know it returns a datatable.

This exact same idea is what I want to apply to my beginner's mobile app. The problem is that I haven't found a simple working example that implements MVVM to this very simple functionality that I want to accomplish. Most of the examples I've found are so convoluted that they confuse more than they help.

So my question is: how can I implement MVVM in this example? It can be pseudocode; it doesn't need to build/compile. I just want to see what it would look like.

Upvotes: 2

Views: 489

Answers (2)

JH_Dev
JH_Dev

Reputation: 446

So just to elaborate on Commands and how they work.

Take a simple login button example.

Your ViewModel will have a Command to handle the login button click like so:

public ICommand LoginCommand {get; set;};

The command needs an action to call when the command is fired.

So in your constructor, you could initialize the command with the following :

LoginCommand = new Command(Login);

The Login Action corresponds to a method you have in your ViewModel like so:

private void Login()
{
   //do login stuff
}

Finally, in your View you Bind the command to your control in this case the login button:

 <Button x:Name="loginButton" Command="{Binding LoginCommand}" Text="Login" />

Upvotes: 2

Ivan I
Ivan I

Reputation: 9990

The problem is that using event handlers is something that you shouldn't do in MVVM. You should bind the Command to the button in this particular case.

Upvotes: 1

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