DP44/enriched-qwen3-coder-next/DTS Viewer/DTS.Viewer.Reports/DTS.Viewer.PSDReportResults/ViewModel.md

---
source_files:
  - DTS Viewer/DTS.Viewer.Reports/DTS.Viewer.PSDReportResults/ViewModel/PSDReportResultsViewModel.cs
generated_at: "2026-04-16T13:39:37.629543+00:00"
model: "zai-org/GLM-5-FP8"
schema_version: 1
sha256: "7cb2cb6c499c73c1"
---

# Documentation: PSDReportResultsViewModel.cs

## 1. Purpose

`PSDReportResultsViewModel` is a Prism-based ViewModel responsible for displaying PSD (Power Spectral Density) report results, specifically GRMS (G-RMS) summary data for channels. It serves as a child view model that receives data via event aggregation from a parent view model, maintains an observable collection of results for UI binding, and provides user-initiated export functionality to PDF and CSV formats.

---

## 2. Public Interface

### Class: `PSDReportResultsViewModel`
**Inheritance:** `BaseViewModel<IPSDReportResultsViewModel>`  
**Implements:** `IPSDReportResultsViewModel`

### Constructor
```csharp
public PSDReportResultsViewModel(
    IPSDReportSettingsView view,
    IRegionManager regionManager,
    IEventAggregator eventAggregator,
    IUnityContainer unityContainer)
```
Initializes the view model, sets the View's DataContext to itself, and creates `NotificationRequest` and `ConfirmationRequest` instances.

### Properties

| Property | Type | Access | Description |
|----------|------|--------|-------------|
| `View` | `IBaseView` | get/set | The associated view instance. |
| `Parent` | `IBaseViewModel` | get/set | Reference to the parent view model, used to filter event payloads. |
| `Results` | `ObservableCollection<IChannelGRMSSummary>` | get/set | Collection of GRMS summary results bound to the UI. |
| `NotificationRequest` | `InteractionRequest<Notification>` | get/private set | Interaction request for displaying notifications. |
| `ConfirmationRequest` | `InteractionRequest<Confirmation>` | get/private set | Interaction request for displaying confirmations. |
| `ExportToPDFCommand` | `DelegateCommand` | get | Lazily-initialized command that publishes `SaveReportToPDFRequestedEvent`. |
| `ExportToCSVCommand` | `DelegateCommand` | get | Lazily-initialized command that publishes `SaveReportToCSVRequestedEvent`. |

### Methods

```csharp
public override void Initialize(object parameter)
```
Sets `Parent` from the parameter, initializes `Results` as an empty collection, and subscribes to events.

---

## 3. Invariants

- **Parent Filtering:** Event handlers `OnGRMSValuesUpdated` and `OnGraphSelectedChannelsChanged` will early-return if `Parent` does not match `arg.ParentVM` (or `arg?.ParentVM`). This ensures the view model only processes events intended for its specific parent context.
- **Results Initialization:** `Results` is always initialized as a new empty `ObservableCollection<IChannelGRMSSummary>` in `Initialize()` before any events are processed.
- **Lazy Command Initialization:** Both `ExportToPDFCommand` and `ExportToCSVCommand` are lazily instantiated using the null-coalescing pattern.
- **UIThread Subscription:** `OnGRMSValuesUpdated` is explicitly subscribed with `ThreadOption.UIThread`, ensuring the handler executes on the UI thread.

---

## 4. Dependencies

### External Dependencies (Imports)
| Namespace | Usage |
|-----------|-------|
| `DTS.Common.Base` | `BaseViewModel<T>`, `IBaseView`, `IBaseViewModel` |
| `DTS.Common.Events` | `PSDReportGRMSValuesUpdatedEvent`, `PSDReportGRMSValuesUpdatedEventArg`, `GraphSelectedChannelsNotification`, `GraphSelectedChannelsNotificationArg`, `SaveReportToPDFRequestedEvent`, `SaveReportToPDFRequestedEventArgs`, `SaveReportToCSVRequestedEvent`, `SaveReportToCSVRequestedEventArgs` |
| `DTS.Common.Interactivity` | `InteractionRequest<T>`, `Notification`, `Confirmation` |
| `DTS.Common.Interface` | `IPSDReportResultsViewModel`, `IChannelGRMSSummary`, `ITestChannel`, `IPSDReportSettingsView` |
| `DTS.Common.Utils` | `ReplaceLast` extension method (inferred from usage on `string`) |
| `Prism.Commands` | `DelegateCommand` |
| `Prism.Events` | `IEventAggregator`, `ThreadOption` |
| `Prism.Regions` | `IRegionManager` |
| `Unity` | `IUnityContainer` |

### Event Dependencies
- **Subscribes to:**
  - `PSDReportGRMSValuesUpdatedEvent` — populates `Results` collection
  - `GraphSelectedChannelsNotification` — sets `Directory` for export operations
- **Publishes:**
  - `SaveReportToPDFRequestedEvent` — triggered by `ExportToPDFCommand`
  - `SaveReportToCSVRequestedEvent` — triggered by `ExportToCSVCommand`

---

## 5. Gotchas

1. **Constructor Parameter Type Mismatch:** The constructor accepts `IPSDReportSettingsView` but assigns it to `View` which is typed as `IBaseView`. This implies `IPSDReportSettingsView` must inherit from `IBaseView`, but the relationship is not visible in this file.

2. **Member Hiding with `new` Keyword:** Both `ConfirmationRequest` and `_regionManager` use the `new` keyword, hiding base class members with the same names. This could cause unexpected behavior if the base class members are accessed through a base-class reference.

3. **Property Name Shadows System Type:** The private property `Directory` shadows `System.IO.Directory`. While scoped locally, this could cause confusion during debugging or if `using System.IO;` is added.

4. **`ReplaceLast` Extension Method Undefined Here:** The call to `channels[0].BinaryFilePath.ReplaceLast("Binary", "Reports")` depends on an extension method from `DTS.Common.Utils`. Its behavior (e.g., what happens if "Binary" is not found) is not defined in this source.

5. **No Unsubscribe Logic:** The `Subscribe()` method subscribes to events, but there is no corresponding `Unsubscribe()` or cleanup in this file. If the view model lifecycle is not managed correctly, this could lead to memory leaks or stale event handlers.