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Views and downloads the current version of a document, with special handling for FileCloud-stored documents versus locally stored documents.

Purpose

This method is part of a document management system that handles viewing/downloading document versions. It checks if the current document version is stored in FileCloud (external storage) or locally, then retrieves and initiates a download of the document file. It provides error handling and user notifications through a notification area UI component.

Source Code

def _view_document(self, event=None):
    """View the current document version"""
    if not self.current_version:
        self.notification_area.object = "**Error:** No document version available"
        return
        
    # Get version UID
    version_uid = self.current_version.get('UID')
    
    # For FileCloud stored documents, we retrieve from there
    try:
        # Is this stored in FileCloud?
        storage_type = self.current_version.get('storage_type', '')
        
        if (storage_type == 'FILECLOUD' and self.current_version.get('filecloud_link')):
            # Get the file from FileCloud using the link
            from CDocs.controllers.filecloud_controller import download_document_from_filecloud
            doc_content = download_document_from_filecloud(
                user=self.user,
                document_uid=self.document_uid
            )
            
            # Handle response correctly based on what download_document_from_filecloud returns
            if isinstance(doc_content, bytes):
                # Direct bytes content
                file_data = io.BytesIO(doc_content)
                file_name = self.current_version.get('file_name', 'document.pdf')
                pn.state.execute_download(file_data, filename=file_name)
            else:
                # Handle dictionary response if that's what the function returns
                self.notification_area.object = "**Error:** Could not download document from FileCloud"
        else:
            # Fall back to default document retrieval
            self._download_current_version(event)
    except Exception as e:
        logger.error(f"Error viewing document: {e}")
        self.notification_area.object = f"**Error:** {str(e)}"

Parameters

Parameter Details

self: Instance reference to the containing class. Expected to have attributes: current_version (dict with document metadata), notification_area (UI component for displaying messages), user (user object), and document_uid (unique identifier for the document).

event: Optional event parameter, typically passed by UI event handlers (e.g., button clicks). Defaults to None. Not directly used in the function body but may be passed to _download_current_version.

Return Value

Returns None implicitly. The function performs side effects: either initiates a file download via pn.state.execute_download(), displays error messages in the notification_area, or calls _download_current_version() as a fallback.

Dependencies

• panel
• io
• logging
• CDocs.controllers.filecloud_controller
• CDocs

Required Imports

import io
import panel as pn
import logging

Conditional/Optional Imports

These imports are only needed under specific conditions:

from CDocs.controllers.filecloud_controller import download_document_from_filecloud

Usage Example

# Assuming this is a method in a DocumentViewer class
# Example usage within a Panel application:

import panel as pn
import io
from CDocs.controllers.filecloud_controller import download_document_from_filecloud

class DocumentViewer:
    def __init__(self, user, document_uid):
        self.user = user
        self.document_uid = document_uid
        self.notification_area = pn.pane.Markdown('')
        self.current_version = {
            'UID': 'doc-123-v1',
            'storage_type': 'FILECLOUD',
            'filecloud_link': 'https://filecloud.example.com/doc123.pdf',
            'file_name': 'document_v1.pdf'
        }
    
    def _download_current_version(self, event=None):
        # Fallback method for local storage
        pass
    
    def _view_document(self, event=None):
        # ... (the function code here)
        pass

# Create viewer instance
viewer = DocumentViewer(user=current_user, document_uid='doc-123')

# Create a button to trigger document viewing
view_button = pn.widgets.Button(name='View Document')
view_button.on_click(viewer._view_document)

# Display in Panel app
app = pn.Column(view_button, viewer.notification_area)
app.show()

Best Practices

• Ensure self.current_version is populated before calling this method to avoid the 'No document version available' error
• The function assumes a logger is configured at module level; ensure logging is properly set up
• This method should only be called within a Panel application context where pn.state.execute_download() is available
• The download_document_from_filecloud function should return bytes for successful downloads; verify this contract is maintained
• Consider adding more specific exception handling instead of catching all exceptions to better diagnose issues
• The notification_area should be a Panel component that supports Markdown formatting (uses ** for bold)
• Ensure proper permissions are checked before allowing document viewing (this function doesn't check permissions itself)
• The fallback to _download_current_version should be implemented in the containing class for non-FileCloud documents

Tags

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