generate-excel-report

name	generate-excel-report
description	Scaffold a new endpoint to generate and download a high-performance Excel report using MiniExcel.
argument-hint	Entity name (e.g., Customer)

Generate Excel Report Scaffold

Creates a high-performance Excel export endpoint for a given entity using the MiniExcel library.

When to Use

• When the user requests an endpoint to download an Excel sheet with the records of an entity.
• To export filtered data in an optimized way without allocating large strings in memory.

Guidelines

• No Pagination: Export endpoints must return ALL records that match the given filters, ignoring any pagination parameters (page, pageSize).
• DTO Projection: ALWAYS export DTOs (e.g., ProductResponseDto), NEVER raw Domain Entities, to ensure proper column names and avoid exposing sensitive internal state.
• FastMode: MiniExcel should be configured with FastMode = true and EnableAutoWidth = true via OpenXmlConfiguration.
• MemoryStream: Data must be written directly to a MemoryStream and returned via the File() helper.

Procedure

1. API Controller

1. Open the target controller (e.g., src/Server/Api/Controllers/{Name}Controller.cs).
2. Add a new [HttpGet("ExportToExcel")] endpoint.
3. Accept the same filtering query parameters ([FromQuery]) that the GetAll endpoint uses, but DO NOT accept page or pageSize.
4. Accept a CancellationToken.
5. Call the service to retrieve all filtered items without pagination.
6. Initialize the OpenXmlConfiguration.
7. Write the items to a MemoryStream using await memoryStream.SaveAsAsync(items, sheetName: "{Name}s", configuration: config);.
8. Reset the stream position (memoryStream.Seek(0, SeekOrigin.Begin);).
9. Return the file using return File(memoryStream, "application/vnd.openxmlformats-officedocument.spreadsheetml.sheet", "{Name}s_{DateTime.Now:yyyyMMdd_HHmmss}.xlsx");.

Reference Template

[HttpGet("ExportToExcel")]
public async Task<ActionResult> ExportToExcelAsync(
  [FromQuery] string? someFilter,
  CancellationToken cancellationToken)
{
  // 1. Fetch data without pagination
  var (items, _) = await _service.GetAllAsync(someFilter, page: null, pageSize: null, cancellationToken);
  
  // 2. Configure MiniExcel
  var config = new OpenXmlConfiguration
  {
    FastMode = true,
    EnableAutoWidth = true,
    AutoFilter = true
  };

  // 3. Write to memory stream
  var memoryStream = new MemoryStream();
  await memoryStream.SaveAsAsync(items.ToList(), sheetName: "Report", configuration: config);
  memoryStream.Seek(0, SeekOrigin.Begin);

  // 4. Return as file
  return File(
    memoryStream,
    "application/vnd.openxmlformats-officedocument.spreadsheetml.sheet",
    $"Report_{DateTime.Now:yyyyMMdd_HHmmss}.xlsx");
}