CachedItemsListViewModel Documentation

1. Purpose

CachedItemsListViewModel is a Prism/MEF view model for the Cached Items List module within the DTS (Data Test System) test setup framework. It serves as the presentation logic layer for displaying and managing cached items—specifically sensors, hardware components, and sensor calibrations—comparing in-memory cached data against database records to identify discrepancies. The class implements the INotifyPropertyChanged pattern and integrates with the application's event aggregation and region management infrastructure.

2. Public Interface

Constructor

public CachedItemsListViewModel(ICachedItemsListView view, IRegionManager regionManager, IEventAggregator eventAggregator, IUnityContainer unityContainer)

Initializes the view model, sets the view's DataContext, creates interaction requests, and subscribes to RaiseNotification and BusyIndicatorChangeNotification events.

Properties

Property	Type	Description
`View`	`ICachedItemsListView`	The associated view instance.
`NotificationRequest`	`InteractionRequest<Notification>`	Used to raise notification dialogs.
`ConfirmationRequest`	`InteractionRequest<Confirmation>`	Used to raise confirmation dialogs.
`CachedItems`	`ICachedItem[]`	Array of cached items. Initialized to empty array.
`IsDirty`	`bool`	Always returns `false`.
`IsBusy`	`bool`	Busy indicator state, triggers `PropertyChanged`.
`IsMenuIncluded`	`bool`	Menu inclusion flag, triggers `PropertyChanged`.
`IsNavigationIncluded`	`bool`	Navigation inclusion flag, triggers `PropertyChanged`.
`HasOutofDateCachedItems`	`bool`	Returns `true` if `CachedItems` contains any elements.
`HasMissingSensors`	`bool`	Returns `true` if any cached item has `DBTime == DateTime.MinValue` and `ObjectType == Resources.StringResources.Sensor`.

Events

public event PropertyChangedEventHandler PropertyChanged

Standard INotifyPropertyChanged event.

Methods

public void OnPropertyChanged(string propertyName)

Invokes the PropertyChanged event if handlers are attached.

public void Unset()
public void Cleanup()
public Task CleanupAsync()
public void Initialize()
public void Initialize(object parameter)
public void Initialize(object parameter, object model)
public Task InitializeAsync()
public Task InitializeAsync(object parameter)
public void Activated()

Lifecycle methods—currently all empty implementations. CleanupAsync, InitializeAsync, and InitializeAsync(object parameter) return Task.CompletedTask.

public bool SetCachedItems(ISensorData[] sensors, ISensorCalibration[] sensorCalibrations, IDASHardware[] hardware, IDASHardware[] allDAS)

Intended to populate CachedItems by comparing provided sensors, calibrations, and hardware against database records. Currently returns false immediately; all logic is commented out.

3. Invariants

Singleton lifetime: The class is decorated with [PartCreationPolicy(CreationPolicy.Shared)], ensuring a single shared instance via MEF.
IsDirty is always false: The property has no backing logic to track actual dirty state.
CachedItems is never null: Property is initialized to an empty array new ICachedItem[0].
Event subscriptions are keep-subscribed: BusyIndicatorChangeNotification is subscribed with keepSubscriberReferenceAlive: true, preventing weak reference cleanup.
HasOutofDateCachedItems naming: Despite the name, it simply checks if any items

3.8 KiB Raw Blame History