django-qs2csv 0.2.2

A simple package to convert a Django QuerySet to a CSV file through an HttpResponse object.

django-qs2csv

A simple package to convert a Django QuerySet to a CSV file through an HttpResponse object.

Getting started

Prerequisites

• Python >= 3.8
• Django >= 3.2

Optional Dependencies

• pandas >= 1.5

Installation

Recommended

pip install django-qs2csv

Full

pip install django-qs2csv[pd]

Note: this will install pandas, which is used with queryset_to_csv_pd(). It is not recommended to install the pandas library unless you will use this function or already use pandas. Using queryset_to_csv_pd() will likely increase the export speed of large QuerySets (2M+ results) and decrease file size for all QuerySets.

Usage

views.py

from django_qs2csv import qs_to_csv

from .models import SampleModel

...

def export_csv(request):
    ...

    my_queryset = SampleModel.objects.all()

    response = qs_to_csv(
        my_queryset,
        filename="all_sample_models",
    )

    return response

Return type

qs_to_csv returns a django.http.HttpResponse with the Content-Type and Content-Disposition headers. Additional headers can be added to the response before returning:

...

response = qs_to_csv(my_queryset)
response["Another-Header"] = "This is another header for the HttpResponse."

...

Parameters

qs : QuerySet - Required. The QuerySet to be exported as a CSV file. This can be passed as QuerySet[object], QuerySet[dict] (values()), or QuerySet[list[tuple]] (values_list()). See the note in the Limitations about QuerySet evaluation.

header : bool - Include a header row with field names. Default: False

filename : str - The name of the exported CSV file. You do not need to include .csv, it will be added once the filename is evaluated. File names can not end in a period, include the symbols (< > : " / \ | ? *), or be longer than 251 characters (255 w/ ".csv"). Default: "export"

only : list[str] - List the field names that you would like to include in the exported file. An empty list will include all fields, other than those in defer. Field names listed in both only and defer will not be included. See the note in the Limitations section for details how this works with a QuerySet that calls only() / defer(). Default: []

defer : list[str] - List the field names that you do not want to include in the exported file. An empty list will include all fields, or just those mentioned in only. Field names listed in both only and defer will not be included. See the note in the Limitations section for details how this works with a QuerySet that calls only() / defer(). Default: []

verbose : bool - Determine if the header row uses the fields' verbose_name or just the field names. This only applies when header=True. Default: True

values : bool - Only enable this if your QuerySet was already evaluated (no longer lazy) and called values(). You must ensure your fields are properly selected in the original QuerySet, because this will skip applying the only and defer parameters. Default: False

Limitations

If the QuerySet was already evaluated before being passed to qs_to_csv then it will be re-evaluated by the function. Depending on the size of the QuerySet, complexity of the query and the database setup, this may add a noticeable delay. It is recommended to monitor the impact of database queries using django.db.connection.queries or django-debug-toolbar during development. If the QuerySet must be evaluated before the function is called, it would be most efficient to use values() with the QuerySet (if possible) then pass values=True to qs_to_csv.

If your QuerySet uses only() / defer() then you must include those same fields in the only / defer parameters when calling qs_to_csv. The function transforms all QuerySets into a list of dicts using values(), which is incompatible with only() and defer().

ForeignKey and OneToOneField will always return the primary key, because the function uses values().

ManyToManyField is not supported.

License

This project is licensed under the MIT License - see the LICENSE.md file for details.