File operations IPC

import-email-list opens a dialog. read-email-list-file parses the chosen path. Both live in the main process so the renderer never touches the filesystem directly.

The file operation IPC handlers are implemented in the Electron main process and exposed to the renderer via a secure preload bridge. The frontend component demonstrates usage of these handlers to import and parse email lists.

graph TB
FE["Frontend Component<br/>BulkMailer.jsx"] --> Preload["Preload Bridge<br/>preload.js"]
Preload --> Main["Main Process Handlers<br/>main.js"]
Main --> FS["File System<br/>fs module"]
Main --> CSV["CSV Parser<br/>csv-parser"]
Main --> Dialog["Dialog API<br/>electron.dialog"]
FE --> |"invoke 'import-email-list'"| Preload
FE --> |"invoke 'read-email-list-file'"| Preload
FE --> |"progress events"| FE

• IPC handler ‘import-email-list’: Opens a native file open dialog configured to accept text and CSV files, returning a structured result object containing the selected file paths and cancellation status.
• IPC handler ‘read-email-list-file’: Reads the content of a given file path, parses CSV files using flexible column detection, and processes text files by extracting lines containing ‘@’. Returns a newline-delimited string of validated email addresses.

Key responsibilities:

• Dialog configuration and file filter options
• Path resolution and file type detection
• CSV parsing with flexible column detection
• Text file processing and email validation
• Error propagation and handling

The file operation IPC flow connects the frontend UI to the Electron main process, which interacts with the file system and parsers.

sequenceDiagram
participant UI as "BulkMailer.jsx"
participant Bridge as "preload.js"
participant Main as "main.js"
participant FS as "fs module"
participant CSV as "csv-parser"
UI->>Bridge : invoke 'import-email-list'
Bridge->>Main : ipcMain.handle('import-email-list')
Main->>Main : dialog.showOpenDialog(filters)
Main-->>Bridge : { canceled, filePaths[] }
Bridge-->>UI : result
UI->>Bridge : invoke 'read-email-list-file', filePath
Bridge->>Main : ipcMain.handle('read-email-list-file')
alt filePath endsWith '.csv'
Main->>FS : createReadStream(filePath)
FS-->>Main : stream
Main->>CSV : pipe(csv())
CSV-->>Main : rows
Main->>Main : detect email column/fallback
Main-->>Bridge : newline-delimited emails
else text file
Main->>FS : readFileSync(filePath, 'utf8')
FS-->>Main : content
Main->>Main : split by newline, filter '@'
Main-->>Bridge : newline-delimited emails
end
Bridge-->>UI : parsed emails

IPC handler: import-email-list#

Purpose:

• Presents a native file open dialog to select an email list file.
• Filters accepted file types to text and CSV files plus all files.

Dialog configuration:

• Properties: openFile
• Filters:
• Text Files: txt
• CSV Files: csv
• All Files: * (fallback)

Return value schema:

• canceled: boolean indicating whether the dialog was canceled
• filePaths: array of selected file paths (only the first path is used in the frontend)

Usage in frontend:

• Invoked via window.electronAPI.importEmailList()
• On success, the first filePath is passed to read-email-list-file

Notes:

• The handler returns the raw dialog result, allowing the renderer to decide how to process the file.

IPC handler: read-email-list-file#

Purpose:

• Reads and parses the content of a selected email list file.
• Supports CSV and text formats with flexible email detection.

Processing logic:

• CSV parsing:
• Uses streaming to avoid memory pressure on large files.
• Detects email columns by common names (email, Email, EMAIL, address, Address, ADDRESS) or falls back to the first column.
• Validates entries by presence of ‘@’.
• Joins extracted emails with newline separators.
• Text file processing:
• Splits content by newline.
• Trims whitespace and filters lines containing ‘@’.

Return value schema:

• String containing newline-delimited email addresses.
• Throws errors on file access failures or parsing errors.

Error handling:

• Catches and rethrows errors from file system operations and CSV parsing.
• Frontend displays error messages and prevents silent failures.

Path resolution:

• Relies on the filePath provided by the caller (import-email-list result).
• No additional path normalization is performed in the handler.

Frontend integration#

• The frontend component invokes import-email-list, checks for cancellation, extracts the first file path, and calls read-email-list-file.
• Displays the count of imported email addresses and handles errors gracefully.

Validation and processing:

• The frontend performs additional email format validation using a regex before sending emails.
• This complements the handler’s basic ‘@’ check.

Supporting utilities#

• Development environment detection is available for logging and conditional behavior.
• The project README documents security features including context isolation and secure IPC.

The file operation handlers depend on:

• Electron dialog API for file selection
• Node.js fs module for file reading
• csv-parser for streaming CSV parsing
• Frontend preload bridge for secure IPC invocation

graph LR
BM["BulkMailer.jsx"] --> P["preload.js"]
P --> M["main.js"]
M --> D["electron.dialog"]
M --> F["fs"]
M --> C["csv-parser"]

• Streaming CSV parsing: The handler streams CSV data to avoid loading entire files into memory, improving performance for large datasets.
• Text file processing: Simple line-by-line processing with minimal allocations.
• Frontend validation: Regex-based validation occurs after parsing to reduce unnecessary network calls.

Recommendations:

• Prefer CSV format for structured data to use flexible column detection.
• For very large files, consider chunked processing and progress reporting.
• Ensure adequate delay between operations to avoid overwhelming the system.

Common issues and resolutions:

• Dialog canceled or no file selected:
• The handler returns canceled true and empty filePaths. The frontend should check these values before proceeding.
• Unsupported file type:
• The handler does not explicitly reject unsupported extensions; ensure the dialog filters are respected.
• File access failures:
• Errors are thrown and surfaced to the frontend. Verify file permissions and path correctness.
• Parsing errors:
• CSV parsing errors are caught and rethrown. Validate CSV headers or switch to text format with ‘@’ separated entries.

Security considerations:

• Context isolation and secure IPC are enabled, preventing direct Node.js access from the renderer.
• Input sanitization is handled by the frontend email regex validation prior to sending emails.
• Rate limiting is implemented in email handlers to prevent abuse.

Path handling stays in main. The renderer should only display returned emails or error strings, never open arbitrary paths itself.