Noyes - WPF MVVM in Depth

Question 1

Set UserControl.DataContext in XAML

Answer 1

<usercontrol.datacontext></usercontrol.datacontext>

<customerlistviewmodel></customerlistviewmodel>

Question 2

INotifyPropertyChanged ?

Answer 2

public class CustomerListViewModel : INotifyPropertyChanged

{

public event PropertyChangedEventHandler PropertyChanged = delegate { };

use:

PropertyChanged(this, new PropertyChangedEventArgs(“Customers”));

}

Question 3

ObservableCollection in ViewModel

Answer 3

public ObservableCollection<customer> Customers</customer>

{

get

{

return _customers;

}

set

{

if (_customers != value)

{

_customers = value;

PropertyChanged(this, new PropertyChangedEventArgs(“Customers”));

}

}

}

Question 4

Window.Resources

declaration DataTemplate DataType

Answer 4

<window.resources></window.resources>

<datatemplate></datatemplate>

<customerlistview></customerlistview>

<datatemplate></datatemplate>

<orderview></orderview>

<datatemplate></datatemplate>

<orderprepview></orderprepview>

Question 5

DataContext / View-First Construction in code behind

Answer 5

<window.datacontext></window.datacontext>

<mainwindowviewmodel></mainwindowviewmodel>

Ctor_code_behind()

{

this.DataContext = new MainWindowViewModel();

InitializeComponent();

}

Question 6

[CallerMemberName]

Answer 6

_{public class BindableBase : <em>INotifyPropertyChanged</em>}

_{

_{public event <em>PropertyChangedEventHandler</em> PropertyChanged = delegate { };}

_{protected virtual void SetProperty<t>(ref T member, T val,</t>}

_{[CallerMemberName] string propertyName = null)}

_{

_{if (object.<em>Equals</em>(member, val))}

_return;

_{member = val;}

_{OnPropertyChanged();}

_}

_{[NotifyPropertyChangedInvocator]}

_{protected virtual void OnPropertyChanged([CallerMemberName] string propertyName = null)}

_{

_{PropertyChanged?.<em>Invoke</em>(this, new <em>PropertyChangedEventArgs</em>(propertyName));}

_}

_}

Question 7

Event declaration

Answer 7

_{public event <em>Action</em><<em>Guid</em>> PlaceOrderRequested = delegate { };}

_{private void OnPlaceOrder(Customer customer)}

_{

_{PlaceOrderRequested(customer.Id);}

_}

• _{Use it outside:}
• _{_customerListViewModel.PlaceOrderRequested += NavToOrder;}

_{private void NavToOrder(<em>Guid</em> customerId)}

_{

_{_orderViewModel.CustomerId = customerId;}

_{CurrentViewModel = _orderViewModel;}

*

Question 8

ViewModelLocator

Answer 8

_{<usercontrol></usercontrol>}

_{xmlns=”http://schemas.microsoft.com/winfx/2006/xaml/presentation”}

_{xmlns:x=”http://schemas.microsoft.com/winfx/2006/xaml”}

_{xmlns:mc=”http://schemas.openxmlformats.org/markup-compatibility/2006”}

_{xmlns:d=”http://schemas.microsoft.com/expression/blend/2008”}

_{xmlns:local=”clr-namespace:MVVMHookupDemo.Customers”}

_{xmlns:root=”clr-namespace:MVVMHookupDemo”}

_{mc:Ignorable=”d”}

_{d:DesignHeight=”450” d:DesignWidth=”800”}

_{root:ViewModelLocator.AutoWireViewModel=”True”}

_>

_{<grid></grid>}

_{public static class ViewModelLocator}

_{

_{public static readonly <em>DependencyProperty</em> AutoWireViewModelProperty = <em>DependencyProperty</em>.<em>RegisterAttached</em>(“AutoWireViewModel”,}

_{typeof(bool),}

_{typeof(ViewModelLocator),}

_{new <em>PropertyMetadata</em>(default(bool),}

_{AutoWireViewModelChanged));}

_{// d is the element on this attached property is being set}

_{private static void AutoWireViewModelChanged(<em>DependencyObject</em> d, <em>DependencyPropertyChangedEventArgs</em> e)}

_{

_{if (<em>DesignerProperties</em>.<em>GetIsInDesignMode</em>(new <em>DependencyObject</em>())) return;}

_{// get view type name}

_{var viewTypeName = d.<em>GetType</em>().<em>FullName</em>;}

_{var viewModelTypeName = viewTypeName + “Model”;}

_{var viewModelType = Type.<em>GetType</em>(viewModelTypeName);}

_{if (viewModelType != null)}

_{

_{var viewModel = <em>Activator</em>.<em>CreateInstance</em>(viewModelType);}

_{((<em>FrameworkElement</em>)d).<em>DataContext</em> = viewModel;}

_}

_}

_{public static bool GetAutoWireViewModel(<em>DependencyObject</em> obj)}

_{

_{return (bool) obj.<em>GetValue</em>(AutoWireViewModelProperty);}

_}

_{public static void SetAutoWireViewModel(<em>DependencyObject</em> obj, bool value)}

_{

_{obj.<em>SetValue</em>(AutoWireViewModelProperty, value);}

_}

Question 9

Data Binding

Answer 9

Answer 10

_{<grid></grid>}

_{<datagrid></datagrid>}

_{ItemsSource=”{Binding Customers}”}

_{AutoGenerateColumns=”False”}

_{EnableRowVirtualization=”True”}

_{RowDetailsVisibilityMode=”VisibleWhenSelected”}

_{SelectedItem=”{Binding SelectedCustomer}” >}

_{<datagrid.columns></datagrid.columns>}

_{<datagridtextcolumn></datagridtextcolumn>}

_{<datagridtextcolumn></datagridtextcolumn>}

_{<datagridtextcolumn></datagridtextcolumn>}

_{public class CustomerListViewModel}

_{

_{readonly ICustomersRepository _repo = new CustomersRepository();}

_{private <em>ObservableCollection</em><customer> _customers;</customer>}

_{public CustomerListViewModel()}

_{

_{if (<em>DesignerProperties</em>.<em>GetIsInDesignMode</em>(new <em>DependencyObject</em>()))}

_return;

_{Customers = new <em>ObservableCollection</em><customer>(_repo.GetCustomersAsync().<em>Result</em>);</customer>}

_}

_{public <em>ObservableCollection</em><customer> Customers</customer>}

_{

_{get => _customers;}

_{set => _customers = value;}

_}

_}

_{public class Customer}

_{

_{public Customer()}

_{

_{Orders = new <em>List</em><order>();</order>}

_}

_{[<em>Key</em>]}

_{public <em>Guid</em> Id { get; set; }}

_{public <em>Guid</em>? StoreId { get; set; }}

_{public string FirstName { get; set; }}

_{public string LastName { get; set; }}

_{public string FullName { get { return FirstName + “ “ + LastName; } }}

_{public string Phone { get; set; }}

_{public string Email { get; set; }}

_{public string Street { get; set; }}

_{public string City { get; set; }}

_{public string State { get; set; }}

_{public string Zip { get; set; }}

_{public <em>List</em><order> Orders { get; set; }</order>}

_}