francoborrelli / django4-tabular-export

Utilities used to export data into spreadsheets from Django applications.

django4-tabular-export

Note

This version is compatible with Django 4+.

Documentation

This module contains functions which take (headers, rows) pairs and return HttpResponses with either XLSX or CSV downloads and Django admin actions which can be added to any ModelAdmin for generic exports. It provides two functions (export_to_csv_response and export_to_xlsx_response) which take a filename, a list of column headers, and a Django QuerySet, list-like object, or generator and return a response.

Goals

• This project is not intended to be a general-purpose spreadsheet manipulation library. The only goal is to export data quickly and safely.
• The API is intentionally simple, giving you full control over the display and formatting of headers or your data. flatten_queryset has special handling for only two types of data: None will be converted to an empty string and date or datetime instances will serialized using isoformat(). All other values will be specified as the text data type to avoid data corruption in Excel if the values happen to resemble a date in the current locale.
• Unicode-safety: input values, including lazy objects, are converted using Django's force_str function and will always be emitted as UTF-8
• Performance: the code is known to work with data sets up to hundreds of thousands of rows. CSV responses use StreamingHttpResponse, use minimal memory, and start very quickly. Excel (XLSX) responses cannot be streamed but xlsxwriter is one of the faster implementations and its memory-size optimizations are enabled.

Quickstart

Install django4-tabular-export:

pip install django4-tabular-export

Then use it in a project:

from tabular_export.core import export_to_csv_response, export_to_excel_response, flatten_queryset

def my_view(request):
    return export_to_csv_response('test.csv', ['Column 1'], [['Data 1'], ['Data 2']])


def my_other_view(request):
    headers = ['Title', 'Date Created']
    rows = MyModel.objects.values_list('title', 'date_created')
    return export_to_excel_response('items.xlsx', headers, rows)


def export_using_a_generator(request):
    headers = ['A Number']

def my_generator():
    for i in range(0, 100000):
        yield (i, )

  return export_to_excel_response('numbers.xlsx', headers, my_generator())

def export_renaming_columns(request):
    qs = MyModel.objects.filter(foo="…").select_related("…")
    headers, data = flatten_queryset(qs, field_names=['title', 'related_model__title_en'], extra_verbose_names={'related_model__title_en': 'English Title'})
    return export_to_csv_response('custom_export.csv', headers, data)

Admin Integration

There are two convenience admin actions which make it simple to add "Export to Excel" and "Export to CSV" actions:

from tabular_export.admin import export_to_csv_action, export_to_excel_action

class MyModelAdmin(admin.ModelAdmin):
    actions = (export_to_excel_action, export_to_csv_action)

The default columns will be the same as you would get calling values_list on your ModelAdmin's default queryset as returned by ModelAdmin.get_queryset(). If you want to customize this, simply declare a new action on your ModelAdmin which does whatever data preparation is necessary:

from tabular_export.admin import export_to_excel_action

class MyModelAdmin(admin.ModelAdmin):
    actions = ('export_batch_summary_action', )

def export_batch_summary_action(self, request, queryset):
    headers = ['Batch Name', 'My Computed Field']
    rows = queryset.annotate("…").values_list('title', 'computed_field_name')
    return export_to_excel_response('batch-summary.xlsx', headers, rows)
    export_batch_summary_action.short_description = 'Export Batch Summary'

Debugging

The TABULAR_RESPONSE_DEBUG = True setting will cause all views to return HTML tables