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Controllers Documentation

Overview

The Controllers directory contains the API controllers that handle HTTP requests and responses for the Giddh Template Service.

Controller Classes

1. MainController (@/Users/divyanshu/walkover/GiddhTemplate/Controllers/PdfController.cs:10-17)

Purpose: Provides basic health check functionality

Endpoints:

  • GET / - Returns service status

Implementation:

[ApiController]
public class MainController : ControllerBase
{
    [HttpGet("/")]
    public IActionResult Get()
    {
        return Ok("Hello from Giddh template!");
    }
}

Usage:

  • Health monitoring
  • Service availability verification
  • Load balancer health checks

2. PdfController (@/Users/divyanshu/walkover/GiddhTemplate/Controllers/PdfController.cs:19-66)

Purpose: Main API controller for PDF generation functionality

Constructor Dependencies

public PdfController(PdfService pdfService, ISlackService slackService, IConfiguration configuration)

Dependencies:

  • PdfService - Core PDF generation logic
  • ISlackService - Error notification service
  • IConfiguration - Environment configuration access

Endpoints

POST /api/v1/pdf

Purpose: Generate PDF invoice from JSON data

Request:

  • Method: POST
  • Content-Type: application/json
  • Body: JSON object matching Root model structure

Response:

  • Success (200): PDF file with headers:
    • Content-Type: application/pdf
    • Content-Disposition: attachment; filename="invoice.pdf"
  • Error (400): Invalid request format
  • Error (500): PDF generation failure

Implementation Flow:

  1. Request Deserialization:

    var jsonString = JsonSerializer.Serialize(requestObj);
Root request = JsonSerializer.Deserialize<Root>(jsonString,
    new JsonSerializerOptions { PropertyNameCaseInsensitive = true });

  2. Validation:

    if (request == null || string.IsNullOrEmpty(request.Company?.Name))
{
    return BadRequest("Invalid request data. Ensure payload matches expected format.");
}

  3. PDF Generation:

    byte[] pdfBytes = await _pdfService.GeneratePdfAsync(request);

  4. Error Handling:

    if (pdfBytes == null || pdfBytes.Length == 0)
{
    await _slackService.SendErrorAlertAsync(
        url: "api/v1/pdf",
        environment: _environment,
        error: "PDF generation returned empty result.",
        stackTrace: "No stacktrace (service returned empty bytes)."
    );
    return StatusCode(500, new { error = "Failed to generate PDF!" });
}

  5. Response:

    return File(pdfBytes, "application/pdf", "invoice.pdf");

Error Handling Strategy

Validation Errors (400)

  • Missing required fields in request
  • Invalid JSON structure
  • Null or empty company name

Server Errors (500)

  • PDF generation failures
  • Template rendering issues
  • Browser automation problems
  • Automatic Slack notification for production issues

Environment Integration

Environment Detection:

_environment = Environment.GetEnvironmentVariable("ENVIRONMENT");

Usage:

  • Error alert context
  • Environment-specific behavior
  • Logging correlation

API Design Patterns

RESTful Design

  • Resource-based URLs (/api/v1/pdf)
  • HTTP status codes for response indication
  • JSON content negotiation

Dependency Injection

  • Constructor injection for services
  • Interface-based abstractions
  • Scoped service lifetimes

Async/Await Pattern

  • Non-blocking PDF generation
  • Scalable request handling
  • Proper resource disposal

Testing Considerations

Unit Testing

  • Mock PdfService for controller logic testing
  • Mock ISlackService for error handling verification
  • Test request validation scenarios

Integration Testing

  • End-to-end PDF generation flow
  • Error handling with real services
  • Performance testing with large payloads

Sample Test Request

{
  "company": {
    "name": "Test Company",
    "address": "123 Test Street"
  },
  "voucherNumber": "INV-001",
  "voucherDate": "2025-12-23",
  "entries": [
    {
      "accountName": "Test Item",
      "amount": {
        "amountForAccount": 100.00
      }
    }
  ]
}

Security Considerations

Input Validation

  • JSON deserialization with case-insensitive options
  • Required field validation
  • Payload size limitations (implicit via ASP.NET Core)

Error Information Disclosure

  • Generic error messages for client responses
  • Detailed logging for internal debugging
  • Sensitive information excluded from responses

Performance Optimization

Async Operations

  • Non-blocking PDF generation
  • Concurrent request handling
  • Resource-efficient processing

Memory Management

  • Byte array handling for PDF data
  • Proper disposal of resources
  • Streaming responses for large files

Author/Developer: Divyanshu Shrivastava
Last Updated: December 2025