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https://github.com/lazybird/django-solo

Helps working with singletons - things like global settings that you want to edit from the admin site.
https://github.com/lazybird/django-solo

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Helps working with singletons - things like global settings that you want to edit from the admin site.

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README 

        

Django Solo

===========






    +---------------------------+

    |                           |

    |                           |

    |             \             | Django Solo helps working with singletons:

    |             /\            | database tables that only have one row.

    |           >=)'>           | Singletons are useful for things like global

    |             \/            | settings that you want to edit from the admin

    |             /             | instead of having them in Django settings.py.

    |                           | 

    |                           | 

    +---------------------------+



Features

--------



Solo helps you enforce instantiating only one instance of a model in django.



* You define the model that will hold your singleton object.

* django-solo gives helper parent class for your model and the admin classes.

* You get an admin interface that's aware you only have one object.

* You can retrieve the object from templates.

* By enabling caching, the database is not queried intensively.



Use Cases

--------



Django Solo is also great for use with singleton objects that have a one to many relationship. Like the use case below where you have a 'Home Slider" that has many "Slides".



* Global or default settings

* An image slider that has many slides

* A page section that has sub-sections

* A team bio with many team members



There are many cases where it makes sense for the parent in a one to many relationship to be limited to a single instance.



Usage Example



```python

# models.py



from django.db import models

from solo.models import SingletonModel



class SiteConfiguration(SingletonModel):

    site_name = models.CharField(max_length=255, default='Site Name')

    maintenance_mode = models.BooleanField(default=False)



    def __str__(self):

        return "Site Configuration"



    class Meta:

        verbose_name = "Site Configuration"

```



```python

# admin.py



from django.contrib import admin

from solo.admin import SingletonModelAdmin

from config.models import SiteConfiguration



admin.site.register(SiteConfiguration, SingletonModelAdmin)

```



```python

# There is only one item in the table, you can get it this way:

from .models import SiteConfiguration

config = SiteConfiguration.objects.get()



# get_solo will create the item if it does not already exist

config = SiteConfiguration.get_solo()

```



In your model, note how you did not have to provide a `verbose_name_plural` field -

That's because Django Solo uses the `verbose_name` instead.



If you're changing an existing model (which already has some objects stored in the database) to a singleton model, you can explicitly provide the id of the row in the database for django-solo to use. This can be done by setting `singleton_instance_id` property on the model:



```python

class SiteConfiguration(SingletonModel):

    singleton_instance_id = 24

    # (...)

```



Installation

------------



This application requires Django 3.2, 4.0, or 4.1.



* Install the package using `pip install django-solo`

* Add ``solo`` or ``solo.apps.SoloAppConfig`` to your ``INSTALLED_APPS`` setting.



This is how you run tests:



    ./manage.py test solo --settings=solo.tests.settings



And from within `tox`:



```

python -m pip install tox

tox

```



Supported Languages

-------------------



- English

- Spanish

- German



Admin

-----



The standard Django admin does not fit well when working with singleton,

for instance, if you need some global site settings to be edited in the admin.

Django Solo provides a modified admin for that.



![django-solo admin](https://raw.github.com/lazybird/django-solo/master/docs/images/django-solo-admin.jpg "django-solo admin")



* In the admin home page where all applications are listed, we have a `config`

  application that holds a singleton model for site configuration.

* The configuration object can only be changed, there's no link for "add" (1).

* The link to the configuration page (2) directly goes to the form page - no

  need for an intermediary object list page, since there's only one object.

* The edit page has a modified breadcrumb (3) to avoid linking to the

  intermediary object list page.

* From the edit page, we cannot delete the object (4) nor can we add a new one (5).



If you wish to disable the skipping of the object list page, and have the default

breadcrumbs, you should set `SOLO_ADMIN_SKIP_OBJECT_LIST_PAGE` to `False` in your settings.



Availability from templates

---------------------------



The singleton object can be retrieved from template by giving the Django model

dotted path:



```django

{% get_solo 'app_label.ModelName' as my_config %}

```



Example:



```django

{% load solo_tags %}

{% get_solo 'config.SiteConfiguration' as site_config %}

{{ site_config.site_name }}

{{ site_config.maintenance_mode }}

```



If you're extending a template, be sure to use the tag in the proper scope.



Right:



```django

{% extends "index.html" %}

{% load solo_tags %}



{% block content %}

    {% get_solo 'config.SiteConfiguration' as site_config %}

    {{ site_config.site_name }}

{% endblock content %}

```



Wrong:



```django

{% extends "index.html" %}

{% load solo_tags %}

{% get_solo 'config.SiteConfiguration' as site_config %}



{% block content %}

    {{ site_config.site_name }}

{% endblock content %}

```



Caching

-------



By default caching is disabled: every time `get_solo` retrieves the singleton

object, there will be a database query.



You can enable caching to only query the database when initially retrieving the

object. The cache will also be updated when updates are made from the admin.



The cache timeout is controlled via the `SOLO_CACHE_TIMEOUT` settings.

The cache backend to be used is controlled via the `SOLO_CACHE` settings.



Settings

--------



### Template tag name



You can retrieve your singleton object in templates using the `get_solo`

template tag.



You can change the name `get_solo` using the

`GET_SOLO_TEMPLATE_TAG_NAME` setting.



```python

GET_SOLO_TEMPLATE_TAG_NAME = 'get_config'

```



### Admin override flag



By default, the admin is overridden. But if you wish to keep the object list

page (e.g. to customize actions), you can set the `SOLO_ADMIN_SKIP_OBJECT_LIST_PAGE`

to `False`.



```python

SOLO_ADMIN_SKIP_OBJECT_LIST_PAGE = True

```



### Cache backend



Django provides a way to define multiple cache backends with the `CACHES`

settings. If you want the singleton object to be cached separately, you

could define the `CACHES` and the `SOLO_CACHE` settings like this:



```python

CACHES = {

    'default': {

        'BACKEND': 'django.core.cache.backends.memcached.MemcachedCache',

        'LOCATION': '127.0.0.1:11211',

    },

    'local': {

        'BACKEND': 'django.core.cache.backends.locmem.LocMemCache',

    },

}



SOLO_CACHE = 'local'

```



Caching will be disabled if set to `None`.



### Cache timeout



The cache timeout in seconds.



```python

SOLO_CACHE_TIMEOUT = 60*5  # 5 mins

```



### Cache prefix



The prefix to use for the cache key.



```python

SOLO_CACHE_PREFIX = 'solo'

```



Getting the code

================



The code is hosted at https://github.com/lazybird/django-solo/



Check out the latest development version anonymously with:



    $ git clone git://github.com/lazybird/django-solo.git



You can install the package in the "editable" mode like this:



    pip uninstall django-solo  # just in case...

    pip install -e git+https://github.com/lazybird/django-solo.git#egg=django-solo



You can also install a specific branch:



    pip install -e git+https://github.com/lazybird/django-solo.git@my-branch#egg=django-solo



The package is now installed in your project and you can find the code.



To run the unit tests:



    pip install tox

    tox



### Making a release



1. Update [`solo/__init__.py`](solo/__init__.py) `version`



2. Update [`CHANGES`](./CHANGES)



3. Make a new release on GitHub



4. Upload release to PyPI



```shell

tox -e build

```



```shell

tox -e upload

```