A set of helper classes for the basic MVVM app. TrakPropertyChanged implements the INotifyPropertyChanged interface to save
coding. TrakViewModel inherits TrakPropertyChanged and has 2 properties, VMList and EditRecord.
Before you using the ComponentTrak classes or method, you need to register the routines. In the MainPage or App, add a call to
the ComponentTrak.Init.Register static method passing in the developer code given to you when you registered ComponentTrak. Example is
ComponentTrak.Init.Register(“abcd”);
TrakPropertyChanged
Implements the INotifyPropertyChanged interface.
Method:
RaisePropertyChanged(); – Add this method to all properties when you set the value for the property.
Example:
using ComponentTrak.MVVM;
class MyViewModel : TrakPropertyChanged
{
private string _Name = “”;
public string Name { get { return _Name; } set { _Name = value; RaisePropertyChanged(); } }
}
TrakViewModel
Implements the INotifyPropertyChanged interface and has properties for the basic MVVM using C# generics.
Method:
RaisePropertyChanged(); – Add this method to all properties when you set the value for the property.
Properties:
VMList – Declares an observable collection using T.
EditRecord – Declares an edit record.
Example:
Always add the using statement at the top of your cs file.
using ComponentTrak.MVVM;
This class also implements the TrakPRopertyChanged class so you can use the RaisePropertyChanged on any of your custom properties.
class MyViewModel : TrakViewModel
{
private string _Name = “”;
public string Name { get { return _Name; } set { _Name = value; RaisePropertyChanged(); } }
}
In your MyContentPage.xaml to use the built-in list of models, you could bind it to your ListView
<ListView ItemsSource=”{Binding VMList}”/>
In your MyContentPage.xaml to edit a record using the built-in model, you could bind your grid or any control to the EditVMRecord that has a model with multiple properties. This example shows if the model was a customer model with a couple of properties, Name and Address
<Grid BindingContext=”{Binding EDitRecord}”>
<Entry Text=”{Binding Path=Name, Mode=TwoWay}”/>
<Entry Text=”{Binding Path=Address, Mode=TwoWay}”/>
</Grid>
TrakEditViewModel
Implements the INotifyPropertyChanged interface and has properties for the basic MVVM using C# generics.
Method:
RaisePropertyChanged(); – Add this method to all properties when you set the value for the property.
Properties:
VMList – Declares an observable collection using T.
EditRecord – Declares an edit record.
Example:
Always add the using statement at the top of your cs file.
using ComponentTrak.MVVM;
This class also implements the TrakPRopertyChanged class so you can use the RaisePropertyChanged on any of your custom properties.
class MyViewModel : TrakViewModel
{
private string _Name = “”;
public string Name { get { return _Name; } set { _Name = value; RaisePropertyChanged(); } }
private int _Age = 0;
public int Age { get { return _Age; } set { _Age = value; RaisePropertyChanged(); } }
}
In your MyContentPage.xaml to use the built-in list of models, you could bind it to your ListView
<ListView ItemsSource=”{Binding VMList}”/>
In your MyContentPage.xaml to edit a record using the built-in model, you could bind your grid or any control to the EditRecord that has a model with multiple properties. This example shows if the model was a customer model with a couple of properties, Name and Address
<Grid BindingContext=”{Binding EDitRecord}”>
<Entry Text=”{Binding Path=Name, Mode=TwoWay}”/>
<Entry Text=”{Binding Path=Address, Mode=TwoWay}”/>
<Button Text=”Save” IsEnabled=”{Binding Path=IsModelValid}”/>
</Grid>
In this part of the example, we’ll add validation name to be required and string length.
var vm = BindingContext as TrakEditViewModel<Customer>;
vm.ValidateRequired(“Name”, “Name is required”);
vm.ValidateStringLength(“Name”, 3, 100, “Name must be 3 to 100 characters”);
vm.ValidateStringLength(“Name”, 4, 100, “Address must be 4 to 100 characters”);
vm.ValidateRangeLimit(“Age”, 20, 99, “Age must be 20 to 99”);
