C#WebAPI如何處理數據導出

在C# Web API中處理數據導出，通常有以下幾種方法：

1. 使用CSV格式：

創建一個CSV文件并返回給客戶端。以下是一個簡單的示例：

public class ExportController : ApiController
{
    public HttpResponseMessage Get()
    {
        List<Employee> employees = GetEmployees(); // 獲取員工列表

        var response = new HttpResponseMessage(HttpStatusCode.OK);
        response.Content = new StreamContent(new MemoryStream());
        response.Content.Headers.ContentDisposition = new System.Net.Http.Headers.ContentDispositionHeaderValue("attachment");
        response.Content.Headers.ContentDisposition.FileName = "employees.csv";

        using (var writer = new StreamWriter(response.Content.Stream))
        {
            writer.WriteLine("Id,Name,Position,Department");

            foreach (var employee in employees)
            {
                writer.WriteLine($"{employee.Id},{employee.Name},{employee.Position},{employee.Department}");
            }
        }

        return response;
    }

    private List<Employee> GetEmployees()
    {
        // 從數據庫或其他數據源獲取員工列表
        return new List<Employee>
        {
            new Employee { Id = 1, Name = "John Doe", Position = "Software Engineer", Department = "IT" },
            new Employee { Id = 2, Name = "Jane Smith", Position = "Project Manager", Department = "IT" }
        };
    }
}

public class Employee
{
    public int Id { get; set; }
    public string Name { get; set; }
    public string Position { get; set; }
    public string Department { get; set; }
}

2. 使用Excel格式：

可以使用第三方庫，如EPPlus或NPOI，將數據導出為Excel文件。以下是使用EPPlus的示例：

首先，安裝EPPlus庫：

Install-Package EPPlus

然后，創建一個Excel文件并返回給客戶端：

public class ExportController : ApiController
{
    public HttpResponseMessage Get()
    {
        List<Employee> employees = GetEmployees(); // 獲取員工列表

        var response = new HttpResponseMessage(HttpStatusCode.OK);
        response.Content = new StreamContent(new MemoryStream());
        response.Content.Headers.ContentDisposition = new System.Net.Http.Headers.ContentDispositionHeaderValue("attachment");
        response.Content.Headers.ContentDisposition.FileName = "employees.xlsx";

        using (var package = new ExcelPackage())
        {
            var worksheet = package.Workbook.Worksheets.Add("Employees");

            worksheet.Cells["A1"].Value = "Id";
            worksheet.Cells["B1"].Value = "Name";
            worksheet.Cells["C1"].Value = "Position";
            worksheet.Cells["D1"].Value = "Department";

            int row = 2;
            foreach (var employee in employees)
            {
                worksheet.Cells[row, 1].Value = employee.Id;
                worksheet.Cells[row, 2].Value = employee.Name;
                worksheet.Cells[row, 3].Value = employee.Position;
                worksheet.Cells[row, 4].Value = employee.Department;
                row++;
            }

            response.Content.Stream = package.GetAsStream();
        }

        return response;
    }

    private List<Employee> GetEmployees()
    {
        // 從數據庫或其他數據源獲取員工列表
        return new List<Employee>
        {
            new Employee { Id = 1, Name = "John Doe", Position = "Software Engineer", Department = "IT" },
            new Employee { Id = 2, Name = "Jane Smith", Position = "Project Manager", Department = "IT" }
        };
    }
}

public class Employee
{
    public int Id { get; set; }
    public string Name { get; set; }
    public string Position { get; set; }
    public string Department { get; set; }
}

這些方法可以根據您的需求進行擴展和修改。您還可以考慮使用其他格式，如JSON、XML等，以滿足不同的導出需求。