webstack-django-sorting 3.1.1
Easy sorting of tables with Django
Requires Python: >=3.12
Keywords: django, sorting, table

# webstack-django-sorting

## What?

`webstack-django-sorting` is a Django app which allows for easy sorting of
data tables. You don't need to change anything to your views to use it. It
provides sorting links for table headers. It is the perfect companion of
[django-pagination](https://github.com/zyga/django-pagination).

There are other powerful projects to sort tables such as
[django-tables2](https://django-tables2.readthedocs.io/) but I don't like the
high level `render_table` tag because it requires to define the CSS in
`Table` classes or to write custom templates.

A demonstration of the features is provided in `testproj` directory. The file
`testproj/README.md` provides information on how to use it.

## Features

- Django or Jinja2 templates
- Django ORM or Python sorting
- Switches between ascending, descending, and no sorting
- Provides links to sort on different criterions
- Visual feedback on applied ordering
- Supports 3.6+
- Supports translation of link titles

To upgrade to `webstack-django-sorting` v1.0.0+, you must remove the old middleware
`webstack_django_sorting.middleware.SortingMiddleware` from `MIDDLEWARE_CLASSES` list.

## How to use it in your project

The package is available on PyPI:

```shell
uv add webstack-django-sorting
```

For Jinja2 template support, install with the optional dependency:

```shell
uv add webstack-django-sorting[jinja2]
```

The project provides examples of integration with Django and Jinja2 templates.

## For Django templates

1. Add the application to the `INSTALLED_APPS` list:

   ```python
   INSTALLED_APPS = [
       # ...
       'webstack_django_sorting',
   ]
   ```

2. Check the request context processor is loaded in `TEMPLATES` options:

   ```python
   TEMPLATES = [
       {
           'BACKEND': 'django.template.backends.django.DjangoTemplates',
           'DIRS': [],
           'APP_DIRS': True,
           'OPTIONS': {
               'context_processors': [
                   # ...
                   'django.template.context_processors.request',
                   # ...
               ],
           },
       },
   ]
   ```

3. Add this line at the top of your template to load the sorting tags:

   ```html
   {% load sorting_tags %}
   ```

4. Decide on a variable that you would like to sort, and use the
   autosort tag on that variable before iterating over it:

   ```html
   {% autosort object_list %}
   ```

   You can pass the option `nulls=first` (or `nulls=last`) to explicitly define
   the ordering of NULL (not supported by all databases,
   [Indexing ASC, DESC and NULLS FIRST/LAST](https://use-the-index-luke.com/sql/sorting-grouping/order-by-asc-desc-nulls-last))

5. Now, you want to display different headers with links to sort
   your objects_list:

   ```html
   <tr>
     <th>{% anchor first_name _("Name") %}</th>
     <th>{% anchor creation_date _("Creation") %}</th>
   </tr>
   ```

   The first argument is a field or an attribute of the objects list, and the
   second one (optional) is a title that would be displayed. The previous
   snippet will be rendered like this in French:

   ```html
   <tr>
     <th><a href="/path/to/your/view/?sort=first_name" title="Nom">Nom</a></th>
     <th>
       <a href="/path/to/your/view/?sort=creation_date" title="Création"
         >Création</a
       >
     </th>
   </tr>
   ```

   An optional 3rd argument allows you to sort first by descending
   (e.g. show most recent dates first) `{% anchor some_date _("Date") desc %}`

   If your application doesn't support internationalization, you can use a
   simple `{% anchor first_name Name %}`.

## For Jinja2 templates

1. Define the environment in the `TEMPLATES` options:

   ```python
   TEMPLATES = {
       {
           "BACKEND": "django.template.backends.jinja2.Jinja2",
           "DIRS": [],
           "APP_DIRS": True,
           "OPTIONS": {
               "environment": "testproj.testapp.jinja2.env.JinjaEnvironment",
           },
       },
   ]
   ```

2. Your environment file should add `sorting_anchor` and `sort_queryset` to globals:

   ```python
   from jinja2.environment import Environment
   from webstack_django_sorting.jinja2_globals import sorting_anchor, sort_queryset

   class JinjaEnvironment(Environment):
       def __init__(self, **kwargs):
           super().__init__(**kwargs)
           self.globals["sorting_anchor"] = sorting_anchor
           self.globals["sort_queryset"] = sort_queryset
   ```

3. Now, you can generate header links to sort your queryset.

   ```html
   <tr>
     <th>{{ sorting_anchor(request, "created_on", "Date") }}</th>
     <!--...-->
   </tr>

   <tr></tr>
   ```

4. The queryset should be wrapped with `sort_queryset` to use the GET request arguments for sorting:

   ```html
   {% for secret_file in sort_queryset(request, secret_files) %}
   <!--...-->
   {% endfor %}
   ```

That's it!

## Settings

The library provides a few settings that you can define in the Django settings of your project:

### Sort indicators

By default, sort direction is shown using HTML entities (arrows):

- `DEFAULT_SORT_UP`, the HTML character to display the up symbol (' &uarr;' by default).
- `DEFAULT_SORT_DOWN`, the HTML character to display the down symbol (' &darr;' by default).

Alternatively, you can use CSS classes for more flexible styling:

- `SORTING_CSS_CLASS_ASC`, CSS class added to the anchor when sorted ascending (empty by default).
- `SORTING_CSS_CLASS_DESC`, CSS class added to the anchor when sorted descending (empty by default).

Example with CSS classes:

```python
# settings.py
SORTING_CSS_CLASS_ASC = "sorted-asc"
SORTING_CSS_CLASS_DESC = "sorted-desc"
```

This will produce `<a class="sorted-asc" ...>` when sorted ascending, allowing you to style the indicator with CSS:

```css
.sorted-asc::after { content: " \2191"; }  /* Up arrow */
.sorted-desc::after { content: " \2193"; }  /* Down arrow */
```

### Error handling

- `SORTING_INVALID_FIELD_RAISES_404`, if true, a 404 response will be returned on invalid use of query parameters (false by default).

## Default Sort Direction

By default, clicking a column header sorts ascending first. You can change this per-column to sort descending on first click (useful for date columns where you typically want most recent first):

Django template:
```html
{% anchor created_date _("Created") "desc" %}
```

Jinja2 template:
```html
{{ sorting_anchor(request, "created_date", "Created", "desc") }}
```

## Performance Considerations

The library uses Django ORM's `order_by()` for database fields, which is efficient. However, when sorting by model properties or computed attributes (not database fields), it falls back to Python sorting which loads all objects into memory.

For large querysets, ensure you're sorting by database fields only. You can check if a field will use Python sorting:

```python
from webstack_django_sorting.common import need_python_sorting

# Returns True if Python sorting will be used (slower)
need_python_sorting(queryset, "my_property")
```

If you must sort by a computed value on large datasets, consider:
- Adding a database field to store the computed value
- Using database-level annotations
- Limiting the queryset size before sorting