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https://github.com/plainspooky/tomatic

Tomatic is a library that helps to enable automatic configuration for python programs.
https://github.com/plainspooky/tomatic

configuration django python setup

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Tomatic is a library that helps to enable automatic configuration for python programs.

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README 

        
![Tomatic logo](tomatic_logo.png)



**Tomatic** is a library that helps add automatic setup capabilities on **Python** programs and avoids that configuration files became bloated with unnecessary lines of code. It has originally designed to be used in [Django](https://www.djangoproject.com/) projects working directly in `settings.py` but can be used with any other Python program.



TL;DR

--

You've a program and need to use values to setup something but without add them in source code, so you can use **Tomatic** to retrieve these values from environment variables and even forcing a specific data type.



For example:



``` python

from tomatic import Tomatic, fix

from tomatic.buckets import EnvironBucket



t = Tomatic(

    EnvironBucket, static_profile="TLDR"

)



print("value = ", t.VALUE__float__)

```



``` console

$ TLDR__VALUE=3 python tldr.py

value = 3.0

```



Supported data types are boolean, floating point, integer and JSON (use it for dictionaries and lists) and strings.



---



Requirements

--

Requires at least **Python 3.6** due use of type hints ([PEP484](https://www.python.org/dev/peps/pep-0484/)).



Installing

--

Use `pip` to install **Tomatic**, running:



``` shell

pip install tomatic

```



Or you can clone or download this repository for manual install.



Using

--



Let's get an simple use handling with [PortgeSQL](https://www.postgresql.org/) database configuration on a **Django** project...



**You have two setups and one problem...**



One for local development using a local instance of **PostgreSQL**:



``` python

DATABASES = {

    'default': {

        'ENGINE': 'django.db.backends.postgresql_psycopg2',

        'NAME': 'app_database',

        'USER': 'app_user',

        'PASSWORD': '12345',

        'HOST': 'localhost',

        'PORT': '',

    }

}

```



And, for **QA**, that uses a different setup on another database server:



``` python

DATABASES = {

    'default': {

        'ENGINE': 'django.db.backends.postgresql_psycopg2',

        'NAME': 'mastercontrol_qa',

        'USER': 'mc_app_user',

        'PASSWORD': '53f2c97dfbf533411874a0f2f551ee9c',

        'HOST': '172,16.20.13',

        'PORT': 5432,

    }

}

```



There are so many ways to handle with this like you can keep two or more copies of `settings.py`, setup two databases on it, use an environment variables etc... But in all cases you will need to stop development to it.



**Solving the problem with Tomatic**



By the way, this example is using `EnvironBucket` , and it works using environment variables to store KEY/VALUE pairs.



Firstly, add it into `settings.py`:



``` python

from tomatic import Tomatic

from tomatic.buckets import EnvironBucket



t = Tomatic(EnvironBucket, env_profile="TARGET")

```

Then setup database using both KEYS from **Tomatic** and your development settings:



``` python

DATABASES = {

    'default': {

        'ENGINE': 'django.db.backends.postgresql_psycopg2',

        'NAME': t.DB_NAME or 'app_database',

        'USER': t.DB_USER or 'app_user',

        'PASSWORD': t.DB_PASSWD or '12345',

        'HOST': t.DB_HOST or 'localhost',

        'PORT': t.DB_PORT or '',

    }

}

```



Here, if KEY isn't set (or empty) the language will automatically try the value that follows on expression.



The, you need to create a file containing values used to connect in **QA** database server:



``` shell

# .qa-env

QA__DB_NAME='mastercontrol_qa'

QA__DB_USER='mc_app_user'

QA__DB_PASSWD='53f2c97dfbf533411874a0f2f551ee9c'

QA__DB_HOST='172.16.20.13'

QA__DB_PORT='9876'



export QA__DB_NAME QA__DB_USER QA__DB_PASSWD QA__DB_HOST QA__DB_PORT

```



**Runing your Django application**



Now, to run your application for local development just run:



``` shell

python ./manage.py runserver

```



But, for do the same using **QA** settings, run:



``` shell

source .qa-env

```

To load environment variables (only needed at first time) and...



``` shell

TARGET=QA python ./manage.py runserver

```



The **TARGET** value is used by **Tomatic** to build the name of environment variables used to setup `DATABASES` dictionary of `setting.py` file. If value isn't set **Tomatic** return `None` and value that follows in expression is used.



Tips

--

1. You can enforce **Tomatic**  to doesn't accept `None` values adding `raise_if_none` argument:



    ``` python

    from django.core.exceptions import ImproperlyConfigured 



    from tomatic import Tomatic

    t = Tomatic(

        EnvironBucket,

        env_profile="TARGET",

        raise_if_none=ImproperlyConfigured

        )            

    ```

	So, if a KEY returns an empty value, `ImproperlyConfigured` exception will be raised.

	

2. You can remove sensitive data from `settings.py` file and put them as system variables as a static profile:

	``` python    

    t = Tomatic(

        EnvironBucket,

        static_profile="DEFAULT",

        raise_if_none=ImproperlyConfigured

        )

	```

	And access them by environment variables starting with `DEFAULT__` prefix.



3. Environment variables on **Python** are always strings but is possible to force data type conversion by adding a type suffix when getting values:



    * `__bool__` to convert VALUE to boolean

    

    * `__float__` to convert VALUE to floating point;

    

    * `__int__` to convert VALUE to integer;

    

    * `__json__` to convert VALUE to dictionary (or a list) and

    

    * `__str__` to convert VALUE to string (default behavior).

    

	Few examples:



| Environment variable | Data type forced | Result |

| --------------------- | ------------------ | ------ |

| `DEFAULT__DEBUG='true`' | `t.DEBUG__bool__`  | `True` |

| `DEFAULT__LOWEST_PRICE='49.90'` | `t.LOWEST_PRICE__float__` | `49.9` |

| `DEFAULT__PAGE_LIMIT='10'` | `t.PAGE_LIMIT__int__ `| `10` |

| `DEFAULT__ALLOWED_HOSTS='["127.0.0.1", "192.168."]'` | `t.ALLOWED_HOSTS__json__` | `["127.0.0.1", "192.168.",]` |



---

And for more details, please, read the [full documentation](https://plainspooky.github.io/tomatic/index.html).