Admin actions are functions that take three arguments, as follows:

• The current ModelAdmin value
• The current HttpRequest value
• The QuerySet value, which contains the selected items

Perform the following steps to create a custom admin action to export a spreadsheet:

1. Create a ColumnConfig class for spreadsheet column configuration in the admin.py file of the products app, as follows:

# myproject/apps/products/admin.py
from openpyxl import Workbook
from openpyxl.styles import Alignment, NamedStyle, builtins
from openpyxl.styles.numbers import FORMAT_NUMBER
from openpyxl.writer.excel import save_virtual_workbook

from django.http.response import HttpResponse
from django.utils.translation import ugettext_lazy as _
from ordered_model.admin import OrderedTabularInline, OrderedInlineModelAdminMixin

# other imports…

class ColumnConfig:
    def __init__(
            self,
            heading,
            width=None,
            heading_style="Headline 1",
            style="Normal Wrapped",
            number_format=None,
         ):
        self.heading = heading
        self.width = width
        self.heading_style = heading_style
        self.style = style
        self.number_format = number_format

2. Then, in the same file, create the export_xlsx() function:

def export_xlsx(modeladmin, request, queryset):
    wb = Workbook()
    ws = wb.active
    ws.title = "Products"

    number_alignment = Alignment(horizontal="right")
    wb.add_named_style(
        NamedStyle(
            "Identifier", alignment=number_alignment, 
             number_format=FORMAT_NUMBER
        )
    )
    wb.add_named_style(
        NamedStyle("Normal Wrapped", 
         alignment=Alignment(wrap_text=True))
    )

    column_config = {
        "A": ColumnConfig("ID", width=10, style="Identifier"),
        "B": ColumnConfig("Title", width=30),
        "C": ColumnConfig("Description", width=60),
        "D": ColumnConfig("Price", width=15, style="Currency", 
             number_format="#,##0.00 €"),
        "E": ColumnConfig("Preview", width=100, style="Hyperlink"),
    }

    # Set up column widths, header values and styles
    for col, conf in column_config.items():
        ws.column_dimensions[col].width = conf.width

        column = ws[f"{col}1"]
        column.value = conf.heading
        column.style = conf.heading_style

    # Add products
    for obj in queryset.order_by("pk"):
        project_photos = obj.productphoto_set.all()[:1]
        url = ""
        if project_photos:
            url = project_photos[0].photo.url

        data = [obj.pk, obj.title, obj.description, obj.price, url]
        ws.append(data)

        row = ws.max_row
        for row_cells in ws.iter_cols(min_row=row, max_row=row):
            for cell in row_cells:
                conf = column_config[cell.column_letter]
                cell.style = conf.style
                if conf.number_format:
                    cell.number_format = conf.number_format

    mimetype = "application/vnd.openxmlformats-
     officedocument.spreadsheetml.sheet"
    charset = "utf-8"
    response = HttpResponse(
        content=save_virtual_workbook(wb),
        content_type=f"{mimetype}; charset={charset}",
        charset=charset,
    )
    response["Content-Disposition"] = "attachment; 
     filename=products.xlsx"
    return response

export_xlsx.short_description = _("Export XLSX")

3. Then, add the actions setting to ProductAdmin, as follows:

@admin.register(Product)
class ProductAdmin(OrderedInlineModelAdminMixin, admin.ModelAdmin):
    # …
    actions = [export_xlsx]
    # …