C# で GridView を書式付きで Excel にエクスポートする方法

Install-Package IronXL
dotnet add package IronXL

using IronXL;
using IronXl.Styles;

Imports IronXL
Imports IronXl.Styles

using IronXL;
using IronXl.Styles;
using System;
using System.Data;
using System.IO;
using System.Windows.Forms;

DataTable dt = (DataTable)dataGridView1.DataSource;

WorkBook workBook = WorkBook.Create(ExcelFileFormat.XLSX);
WorkSheet sheet = workBook.DefaultWorkSheet;

// Header row -- bold, blue background, white text
for (int col = 0; col < dt.Columns.Count; col++)
{
    sheet.SetCellValue(0, col, dt.Columns[col].ColumnName);
    var cell = sheet.GetCellAt(0, col);
    cell.Style.Font.Bold = true;
    cell.Style.SetBackgroundColor("#4472C4");
    cell.Style.Font.Color = "#FFFFFF";
    cell.Style.BottomBorder.Type = BorderType.Thin;
}

// Data rows -- alternating row color
for (int row = 0; row < dt.Rows.Count; row++)
{
    for (int col = 0; col < dt.Columns.Count; col++)
    {
        string value = dt.Rows[row][col]?.ToString() ?? string.Empty;
        sheet.SetCellValue(row + 1, col, value);

        var cell = sheet.GetCellAt(row + 1, col);
        cell.Style.SetBackgroundColor(row % 2 == 0 ? "#D6DCE5" : "#FFFFFF");
        cell.Style.BottomBorder.Type = BorderType.Thin;
    }
}

// Save via dialog
using var saveDialog = new SaveFileDialog
{
    Filter = "Excel Files|*.xlsx",
    FileName = "GridViewExport.xlsx"
};

if (saveDialog.ShowDialog() == DialogResult.OK)
{
    workBook.SaveAs(saveDialog.FileName);
    MessageBox.Show("Export successful.", "Export",
        MessageBoxButtons.OK, MessageBoxIcon.Information);
}

Imports IronXL
Imports IronXl.Styles
Imports System
Imports System.Data
Imports System.IO
Imports System.Windows.Forms

Dim dt As DataTable = DirectCast(dataGridView1.DataSource, DataTable)

Dim workBook As WorkBook = WorkBook.Create(ExcelFileFormat.XLSX)
Dim sheet As WorkSheet = workBook.DefaultWorkSheet

' Header row -- bold, blue background, white text
For col As Integer = 0 To dt.Columns.Count - 1
    sheet.SetCellValue(0, col, dt.Columns(col).ColumnName)
    Dim cell = sheet.GetCellAt(0, col)
    cell.Style.Font.Bold = True
    cell.Style.SetBackgroundColor("#4472C4")
    cell.Style.Font.Color = "#FFFFFF"
    cell.Style.BottomBorder.Type = BorderType.Thin
Next

' Data rows -- alternating row color
For row As Integer = 0 To dt.Rows.Count - 1
    For col As Integer = 0 To dt.Columns.Count - 1
        Dim value As String = If(dt.Rows(row)(col)?.ToString(), String.Empty)
        sheet.SetCellValue(row + 1, col, value)

        Dim cell = sheet.GetCellAt(row + 1, col)
        cell.Style.SetBackgroundColor(If(row Mod 2 = 0, "#D6DCE5", "#FFFFFF"))
        cell.Style.BottomBorder.Type = BorderType.Thin
    Next
Next

' Save via dialog
Using saveDialog As New SaveFileDialog With {
    .Filter = "Excel Files|*.xlsx",
    .FileName = "GridViewExport.xlsx"
}
    If saveDialog.ShowDialog() = DialogResult.OK Then
        workBook.SaveAs(saveDialog.FileName)
        MessageBox.Show("Export successful.", "Export", MessageBoxButtons.OK, MessageBoxIcon.Information)
    End If
End Using

using IronXL;
using IronXl.Styles;
using System;
using System.Data;
using System.IO;
using System.Web.UI;

// Disable paging so all rows are captured
GridView1.AllowPaging = false;
GridView1.DataBind();

DataTable dt = (DataTable)GridView1.DataSource;

WorkBook workBook = WorkBook.Create(ExcelFileFormat.XLSX);
WorkSheet sheet = workBook.DefaultWorkSheet;

// Header row
for (int col = 0; col < dt.Columns.Count; col++)
{
    sheet.SetCellValue(0, col, dt.Columns[col].ColumnName);
    var cell = sheet.GetCellAt(0, col);
    cell.Style.Font.Bold = true;
    cell.Style.SetBackgroundColor("#2E75B6");
    cell.Style.Font.Color = "#FFFFFF";
    cell.Style.HorizontalAlignment = HorizontalAlignment.Center;
    cell.Style.BottomBorder.Type = BorderType.Medium;
}

// Data rows
for (int row = 0; row < dt.Rows.Count; row++)
{
    for (int col = 0; col < dt.Columns.Count; col++)
    {
        sheet.SetCellValue(row + 1, col, dt.Rows[row][col]?.ToString() ?? string.Empty);
        var cell = sheet.GetCellAt(row + 1, col);
        cell.Style.SetBackgroundColor(row % 2 == 0 ? "#DEEAF1" : "#FFFFFF");
        cell.Style.BottomBorder.Type = BorderType.Thin;
        cell.Style.LeftBorder.Type = BorderType.Thin;
        cell.Style.RightBorder.Type = BorderType.Thin;
    }
}

// Stream to browser
byte[] fileBytes = workBook.ToByteArray();
Response.Clear();
Response.ContentType = "application/vnd.openxmlformats-officedocument.spreadsheetml.sheet";
Response.AddHeader("content-disposition", "attachment; filename=GridViewExport.xlsx");
Response.BinaryWrite(fileBytes);
Response.End();

Imports IronXL
Imports IronXl.Styles
Imports System
Imports System.Data
Imports System.IO
Imports System.Web.UI

' Disable paging so all rows are captured
GridView1.AllowPaging = False
GridView1.DataBind()

Dim dt As DataTable = DirectCast(GridView1.DataSource, DataTable)

Dim workBook As WorkBook = WorkBook.Create(ExcelFileFormat.XLSX)
Dim sheet As WorkSheet = workBook.DefaultWorkSheet

' Header row
For col As Integer = 0 To dt.Columns.Count - 1
    sheet.SetCellValue(0, col, dt.Columns(col).ColumnName)
    Dim cell = sheet.GetCellAt(0, col)
    cell.Style.Font.Bold = True
    cell.Style.SetBackgroundColor("#2E75B6")
    cell.Style.Font.Color = "#FFFFFF"
    cell.Style.HorizontalAlignment = HorizontalAlignment.Center
    cell.Style.BottomBorder.Type = BorderType.Medium
Next

' Data rows
For row As Integer = 0 To dt.Rows.Count - 1
    For col As Integer = 0 To dt.Columns.Count - 1
        sheet.SetCellValue(row + 1, col, If(dt.Rows(row)(col)?.ToString(), String.Empty))
        Dim cell = sheet.GetCellAt(row + 1, col)
        cell.Style.SetBackgroundColor(If(row Mod 2 = 0, "#DEEAF1", "#FFFFFF"))
        cell.Style.BottomBorder.Type = BorderType.Thin
        cell.Style.LeftBorder.Type = BorderType.Thin
        cell.Style.RightBorder.Type = BorderType.Thin
    Next
Next

' Stream to browser
Dim fileBytes As Byte() = workBook.ToByteArray()
Response.Clear()
Response.ContentType = "application/vnd.openxmlformats-officedocument.spreadsheetml.sheet"
Response.AddHeader("content-disposition", "attachment; filename=GridViewExport.xlsx")
Response.BinaryWrite(fileBytes)
Response.End()

// Auto-size columns 0 through the last column index
for (int col = 0; col < dt.Columns.Count; col++)
{
    // Set column width in character units (1 unit ≈ one default character width)
    sheet.SetColumnWidth(col, 20);
}

// Freeze the first row (index 0) so the header stays visible while scrolling
sheet.FreezeRows(1);

// Optionally set row height for the header (in points)
sheet.SetRowHeight(0, 20);

' Auto-size columns 0 through the last column index
For col As Integer = 0 To dt.Columns.Count - 1
    ' Set column width in character units (1 unit ≈ one default character width)
    sheet.SetColumnWidth(col, 20)
Next

' Freeze the first row (index 0) so the header stays visible while scrolling
sheet.FreezeRows(1)

' Optionally set row height for the header (in points)
sheet.SetRowHeight(0, 20)

using IronXL;
using IronXl.Styles;
using System.Data;

public static byte[] DataTableToExcelBytes(DataTable dt, string sheetName = "Report")
{
    WorkBook workBook = WorkBook.Create(ExcelFileFormat.XLSX);
    WorkSheet sheet = workBook.CreateWorkSheet(sheetName);

    // Header
    for (int col = 0; col < dt.Columns.Count; col++)
    {
        sheet.SetCellValue(0, col, dt.Columns[col].ColumnName);
        var cell = sheet.GetCellAt(0, col);
        cell.Style.Font.Bold = true;
        cell.Style.SetBackgroundColor("#4472C4");
        cell.Style.Font.Color = "#FFFFFF";
    }

    // Data
    for (int row = 0; row < dt.Rows.Count; row++)
    {
        for (int col = 0; col < dt.Columns.Count; col++)
        {
            sheet.SetCellValue(row + 1, col, dt.Rows[row][col]?.ToString() ?? string.Empty);
        }
    }

    return workBook.ToByteArray();
}

Imports IronXL
Imports IronXl.Styles
Imports System.Data

Public Shared Function DataTableToExcelBytes(dt As DataTable, Optional sheetName As String = "Report") As Byte()
    Dim workBook As WorkBook = WorkBook.Create(ExcelFileFormat.XLSX)
    Dim sheet As WorkSheet = workBook.CreateWorkSheet(sheetName)

    ' Header
    For col As Integer = 0 To dt.Columns.Count - 1
        sheet.SetCellValue(0, col, dt.Columns(col).ColumnName)
        Dim cell = sheet.GetCellAt(0, col)
        cell.Style.Font.Bold = True
        cell.Style.SetBackgroundColor("#4472C4")
        cell.Style.Font.Color = "#FFFFFF"
    Next

    ' Data
    For row As Integer = 0 To dt.Rows.Count - 1
        For col As Integer = 0 To dt.Columns.Count - 1
            sheet.SetCellValue(row + 1, col, If(dt.Rows(row)(col)?.ToString(), String.Empty))
        Next
    Next

    Return workBook.ToByteArray()
End Function

// In a Blazor component or service
using IronXL;
using System.Data;
using Microsoft.JSInterop;

public async Task ExportToExcelAsync(DataTable dt, IJSRuntime js)
{
    WorkBook workBook = WorkBook.Create(ExcelFileFormat.XLSX);
    WorkSheet sheet = workBook.DefaultWorkSheet;

    for (int col = 0; col < dt.Columns.Count; col++)
    {
        sheet.SetCellValue(0, col, dt.Columns[col].ColumnName);
        var cell = sheet.GetCellAt(0, col);
        cell.Style.Font.Bold = true;
        cell.Style.SetBackgroundColor("#4472C4");
        cell.Style.Font.Color = "#FFFFFF";
    }

    for (int row = 0; row < dt.Rows.Count; row++)
    {
        for (int col = 0; col < dt.Columns.Count; col++)
        {
            sheet.SetCellValue(row + 1, col, dt.Rows[row][col]?.ToString() ?? string.Empty);
        }
    }

    byte[] fileBytes = workBook.ToByteArray();
    string base64 = Convert.ToBase64String(fileBytes);
    await js.InvokeVoidAsync("downloadFileFromBase64", base64, "GridViewExport.xlsx",
        "application/vnd.openxmlformats-officedocument.spreadsheetml.sheet");
}

Imports IronXL
Imports System.Data
Imports Microsoft.JSInterop

Public Async Function ExportToExcelAsync(dt As DataTable, js As IJSRuntime) As Task
    Dim workBook As WorkBook = WorkBook.Create(ExcelFileFormat.XLSX)
    Dim sheet As WorkSheet = workBook.DefaultWorkSheet

    For col As Integer = 0 To dt.Columns.Count - 1
        sheet.SetCellValue(0, col, dt.Columns(col).ColumnName)
        Dim cell = sheet.GetCellAt(0, col)
        cell.Style.Font.Bold = True
        cell.Style.SetBackgroundColor("#4472C4")
        cell.Style.Font.Color = "#FFFFFF"
    Next

    For row As Integer = 0 To dt.Rows.Count - 1
        For col As Integer = 0 To dt.Columns.Count - 1
            sheet.SetCellValue(row + 1, col, If(dt.Rows(row)(col)?.ToString(), String.Empty))
        Next
    Next

    Dim fileBytes As Byte() = workBook.ToByteArray()
    Dim base64 As String = Convert.ToBase64String(fileBytes)
    Await js.InvokeVoidAsync("downloadFileFromBase64", base64, "GridViewExport.xlsx", "application/vnd.openxmlformats-officedocument.spreadsheetml.sheet")
End Function