Action to export to csv in Django 2.0

actions.py

# Action Export CSV to DJANGO 2.0
import csv
from django.http import HttpResponse


def export_csv(modeladmin, request, queryset):
    response = HttpResponse(content_type="text/csv")
    response['Content-Disposition'] = 'attachment; filename="export.csv"'
    writer = csv.writer(response)

    if hasattr(modeladmin, 'list_export'):
        fields = modeladmin.list_export
    else:
        fields = modeladmin.list_display

    if hasattr(modeladmin, 'head_export'):
        head_export = getattr(modeladmin, 'head_export')
    else:
        head_export = True

    if head_export:
        head = []
        for field in fields:
            if field == '__str__':
                verbose_name = queryset.model._meta.verbose_name
            else:
                verbose_name = queryset.model._meta.get_field(field).verbose_name
            
            head.append(verbose_name)
        writer.writerow(head)

    for obj in queryset:
        body = []
        for field in fields:
            if field == '__str__':
                value = str(obj)
            else:
                value = getattr(obj, field)

                if queryset.model._meta.get_field(field).choices:
                    value = '{} - {}'.format(value, getattr(obj, 'get_' + field + '_display')())
            body.append(value)
        writer.writerow(body)
    return response

admin.py

from django.contrib import admin
from .actions import export_csv
from .models import Foo

export_csv.short_description = 'Export CSV'

# Example 1
@admin.register(Foo)
class ModelAdmin(admin.ModelAdmin):
    list_display = ['created_at', 'status', 'client']
    actions = [export_csv]

# Example 2
@admin.register(Foo)
class ModelAdmin(admin.ModelAdmin):
    list_display = ['created_at', 'status', 'client']
    list_export = ['client']
    actions = [export_csv]
  
# Example 3
@admin.register(Foo)
class ModelAdmin(admin.ModelAdmin):
    actions = [export_csv]
    head_export = False # Default is True
    list_export = ['client']
    
# Example 4
# Global
admin.site.add_action(export_csv, 'export_csv')