65 lines
4.7 KiB
Markdown
65 lines
4.7 KiB
Markdown
---
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source_files:
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- Common/DTS.Common/Events/DTS.Viewer/Reports/SaveReportToCSVRequestedEvent.cs
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- Common/DTS.Common/Events/DTS.Viewer/Reports/SaveReportToPDFRequestedEvent.cs
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generated_at: "2026-04-16T03:27:02.713322+00:00"
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model: "Qwen/Qwen3-Coder-Next-FP8"
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schema_version: 1
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sha256: "c23355273750380a"
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---
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# Reports
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## Documentation: Report Export Request Events
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### 1. Purpose
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This module defines Prism-based pub/sub events used to signal user-initiated requests to export report data to external formats—specifically CSV and PDF. These events decouple the UI layer (e.g., a report viewer control or dialog) from the export implementation logic, enabling loose coupling and testability in the MVVM pattern. When a user selects "Save as CSV" or "Save as PDF", the UI publishes the corresponding event, and a dedicated handler (e.g., in a service or view model) subscribes to perform the actual file I/O and export processing.
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### 2. Public Interface
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- **`SaveReportToCSVRequestedEvent`**
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*Type:* `class` inheriting from `PubSubEvent<SaveReportToCSVRequestedEventArgs>`
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*Behavior:* A Prism event used to publish requests to save a report to CSV format. Subscribers receive an instance of `SaveReportToCSVRequestedEventArgs` containing the target directory and parent view model context.
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- **`SaveReportToCSVRequestedEventArgs`**
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*Type:* `class`
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*Properties:*
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- `Directory` (`string`): The file system directory where the CSV file should be saved.
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- `ParentVM` (`IBaseViewModel`): The view model that initiated or owns the report context (e.g., the active report view model). Used for context-aware operations (e.g., resolving data sources or parent window handles).
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- **`SaveReportToPDFRequestedEvent`**
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*Type:* `class` inheriting from `PubSubEvent<SaveReportToPDFRequestedEventArgs>`
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*Behavior:* A Prism event used to publish requests to save a report to PDF format. Subscribers receive an instance of `SaveReportToPDFRequestedEventArgs` with the same payload structure as the CSV variant.
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- **`SaveReportToPDFRequestedEventArgs`**
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*Type:* `class`
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*Properties:*
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- `Directory` (`string`): The file system directory where the PDF file should be saved.
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- `ParentVM` (`IBaseViewModel`): The view model that initiated or owns the report context.
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> **Note:** Both event argument classes are *mutable* (public setters on properties) and lack validation or immutability guarantees.
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### 3. Invariants
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- The `Directory` property in both argument types is expected to be a valid, writable file system path at the time of event publication.
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- The `ParentVM` property is expected to be non-null at event publication; however, no explicit null-checking or enforcement is present in the event argument classes themselves.
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- Events are published *before* export logic executes (i.e., they are request triggers, not completion notifications).
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- No ordering guarantees exist between multiple subscribers—concurrent or conflicting writes to the same path are possible if not handled by subscribers.
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### 4. Dependencies
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- **Internal Dependencies:**
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- `DTS.Common.Base.IBaseViewModel`: Defines the contract for view models used in the parent context.
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- `Prism.Events.PubSubEvent<T>`: Prism’s event aggregation infrastructure.
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- **External Dependencies:**
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- `System` and `System.Collections.Generic`, `System.Linq`, `System.Text`, `System.Threading.Tasks`: Standard .NET libraries.
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- **Consumers (inferred):**
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- UI components (e.g., report viewer controls) that publish these events on user action.
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- Export service classes or view models that subscribe to these events to handle file generation.
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- Likely used in conjunction with `IBaseViewModel` implementations that expose report data and coordinate with export services.
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### 5. Gotchas
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- **No filename specification:** The event arguments only provide a *directory*, not a filename. Subscribers must derive filenames (e.g., via timestamp, report name from `ParentVM`, or user input), which may lead to inconsistent naming or overwrites if not handled carefully.
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- **No cancellation support:** Events lack a mechanism to signal cancellation (e.g., via `CancellationToken`) or to abort the operation mid-process.
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- **No error propagation:** Exceptions thrown by subscribers are not captured or propagated back to the publisher; error handling must be implemented entirely within subscribers.
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- **No format-specific metadata:** Arguments do not include export options (e.g., CSV delimiter, PDF page size, inclusion of headers). Subscribers must hardcode or infer such settings.
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- **Mutable payload:** Since `Directory` and `ParentVM` have public setters, subscribers could inadvertently modify the event args—though this is unlikely to be intentional.
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- **None identified from source alone.** |