Django Advanced Filters
=======================

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A django ModelAdmin mixin which adds advanced filtering abilities to the
admin.

Mimics the advanced search feature in
`VTiger <https://www.vtiger.com/>`__, `see here for more
info <https://www.vtiger.com/docs/creating-custom-filters>`__

.. figure:: https://raw.githubusercontent.com/modlinltd/django-advanced-filters/develop/screenshot.png
   :alt: Creating via a modal
   :width: 768 px


For release notes, see `Changelog <https://raw.githubusercontent.com/modlinltd/django-advanced-filters/develop/CHANGELOG.rst>`__

Requirements
============

-  Django 2.2, >= 3.2 on Python 3.7+/PyPy3
-  simplejson >= 3.6.5, < 4


Installation & Set up
=====================

1. Install from pypi: ``pip install django-advanced-filters``
2. Add ``'advanced_filters'`` to ``INSTALLED_APPS``.
3. Add ``url(r'^advanced_filters/', include('advanced_filters.urls'))``
   to your project's urlconf.
4. Run ``python manage.py syncdb`` or ``python manage.py migrate`` (for django >= 1.7)

Integration Example
===================

Extending a ModelAdmin is pretty straightforward:

.. code-block:: python

    from advanced_filters.admin import AdminAdvancedFiltersMixin

    class ProfileAdmin(AdminAdvancedFiltersMixin, models.ModelAdmin):
        list_filter = ('name', 'language', 'ts')   # simple list filters

        # specify which fields can be selected in the advanced filter
        # creation form
        advanced_filter_fields = (
            'name',
            'language',
            'ts',

            # even use related fields as lookup fields
            'country__name',
            'posts__title',
            'comments__content',
        )

Adding a new advanced filter (see below) will display a new list filter
named "Advanced filters" which will list all the filter the currently
logged in user is allowed to use (by default only those he/she created).

Custom naming of fields
-----------------------

Initially, each field in ``advanced_filter_fields`` is resolved into an
actual model field. That field's verbose\_name attribute is then used as
the text of the displayed option. While uncommon, it occasionally makes
sense to use a custom name, especially when following a relationship, as
the context then changes.

For example, when a profile admin allows filtering by a user name as
well as a sales representative name, it'll get confusing:

.. code-block:: python

    class ProfileAdmin(AdminAdvancedFiltersMixin, models.ModelAdmin):
        advanced_filter_fields = ('name', 'sales_rep__name')

In this case the field options will both be named "name" (by default).

To fix this, use custom naming:

.. code-block:: python

    class ProfileAdmin(AdminAdvancedFiltersMixin, models.ModelAdmin):
        advanced_filter_fields = ('name', ('sales_rep__name', 'assigned rep'))

Now, you will get two options, "name" and "assigned rep".

Adding new advanced filters
===========================

By default the mixin uses a template which extends django's built-in
``change_list`` template. This template is based off of grapelli's fork
of this template (hence the 'grp' classes and funny looking javascript).

The default template also uses the superb
`magnificPopup <dimsemenov/Magnific-Popup>`__ which is currently bundled
with the application.

Regardless of the above, you can easily write your own template which
uses context variables ``{{ advanced_filters }}`` and
``{{ advanced_filters.formset }}``, to render the advanced filter
creation form.

Structure
=========

Each advanced filter has only a couple of required fields when
constructed with the form; namely the title and a formset (consisting of
a form for each sub-query or rule of the filter query).

Each form in the formset requires the following fields: ``field``,
``operator``, ``value``

And allows the optional ``negate`` and ``remove`` fields.

Let us go over each of the fields in a rule fieldset.

Field
-----

The list of all available fields for this specific instance of the
ModelAdmin as specific by the ```advanced_filter_fields``
property. <#integration-example>`__

The OR field
~~~~~~~~~~~~

``OR`` is an additional field that is added to every rule's available
fields.

It allows constructing queries with `OR
statements <https://docs.djangoproject.com/en/dev/topics/db/queries/#complex-lookups-with-q-objects>`__.
You can use it by creating an "empty" rule with this field "between" a
set of 1 or more rules.

Operator
--------

Query field suffixes which specify how the ``WHERE`` query will be
constructed.

The currently supported are as follows: ``iexact``, ``icontains``,
``iregex``, ``range``, ``isnull``, ``istrue`` and ``isfalse``

For more detail on what they mean and how they function, see django's
`documentation on field
lookups <https://docs.djangoproject.com/en/dev/ref/models/querysets/#field-lookups>`__.

Value
-----

The value which the specific sub-query will be looking for, i.e the
value of the field specified above, or in django query syntax:
``.filter(field=value)``

Negate
------

A boolean (check-box) field to specify whether this rule is to be
negated, effectively making it a "exclude" sub-query.

Remove
------

Similarly to other `django
formsets <https://docs.djangoproject.com/en/dev/topics/forms/formsets/>`__,
used to remove the selected line on submit.

Editing previously created advanced filters
===========================================

The ``AdvancedFilterAdmin`` class (a subclass of ``ModelAdmin``) is
provided and registered with ``AdvancedFilter`` in admin.py module.

The model's change\_form template is overridden from grapelli's/django's
standard template, to mirror the add form modal as closely as possible.

*Note:* currently, adding new filters from the ModelAdmin change page is
not supported.

Query Serialization
===================

**TODO:** write a few words on how serialization of queries is done.

Model correlation
=================

Since version 1.0, ``AdvancedFilter`` are tightly coupled with a specific model
using the ``model`` field and the app\_label.Name template.
On creation, ``model`` is populated based on the admin changelist it's created
in.

This change has a few benefits:

1. The mixin can be used with multiple ``ModelAdmin`` classes while
   performing specific query serialization and field validation that are
   at the base of the filter functionality.

2. Users can edit previously created filters outside of the
   context of a changelist, as we do in the
   ```AdvancedFilterAdmin`` <#editing-previously-created-advanced-filters>`__.

3. Limit the ``AdvancedListFilters`` to limit queryset (and thus, the
   underlying options) to a specified model.

Views
=====

The GetFieldChoices view is required to dynamically (using javascript)
fetch a list of valid field choices when creating/changing an
``AdvancedFilter``.

TODO
====

-  Add permission user/group selection functionality to the filter form
-  Allow toggling of predefined templates (grappelli / vanilla django
   admin), and front-end features.
-  Support more (newer) python/django versions

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