Django Application Design Framework

Components

MODULES

Modules should be installed via pip, including modules from github. To install modules from github the following article describes the steps involved.

Structure

projectx
|-- app1
| |-- __init__.py
| |-- models.py 
| |-- views.py
|-- app2
| |-- __init__.py
| |-- models.py
| '-- views.py
|-- appx
| |-- __init__.py
| |-- models.py
| '-- views.py
|-- projectx
| |-- __init__.py
| |-- errorsbase.py
| |-- errorsdrf.py
| |-- settings.py
| |-- urls.py
| |-- wsgi.py
|-- manage.py
|-- modules
| |-- __init__.py
| |-- auth.py
| |-- base.py
| |-- connectors.py
| |-- sorters.py
| |-- threader.py
` |-- models.py

 

Coding Conventions

Throughout your code, the coding conventions of PEP8 should be followed. This will ensure both naming conventions and code layout is produced in a clear and consistent manner.

Below is a small example of the key points,

Naming Conventions

module_name
package_name
ClassName
method_name
ExceptionName
function_name
GLOBAL_CONSTANT_NAME
global_var_name
instance_var_name
function_parameter_name
local_var_name

Code Layout 

Logging

Logging provides a method of ….

Logging is configured by,

  • using the inbuilt logging features of Django. Using the configuration below.
  • logging events will be placed,
    • within the main.py by the
      • return (info)
      • raise (error)
    • within the base.py
      • end of each function (debug)
// settings.py
LOGGING = {
    'version': 1,
    'disable_existing_loggers': False,
    'formatters': {
        'verbose': {
            'format' : "[%(asctime)s] %(levelname)s [%(name)s:%(lineno)s] %(message)s",
            'datefmt' : "%d/%b/%Y %H:%M:%S"
        },
        'simple': {
            'format': '%(levelname)s %(message)s'
        },
    },
    'handlers': {
        'file': {
            'level': 'DEBUG',
            'class': 'logging.FileHandler',
            'filename': 'projectx.log',
            'formatter': 'verbose'
        },
    },
    'loggers': {
        'django': {
            'handlers':['file'],
            'propagate': True,
            'level':'DEBUG',
        },
        'app1': {
            'handlers': ['file'],
            'level': 'DEBUG',
        },
        'app2': {
            'handlers': ['file'],
            'level': 'DEBUG',
        },
        'appX': {
            'handlers': ['file'],
            'level': 'DEBUG',
        },
    }
}
// main.py
import logging
logger = logging.getLogger(__name__)
 
def myfunction():
    do something ... 
    logger.info("do something")

Exceptions

Exceptions should be placed as close to the error as possible. And caught at towards the top layers of the application. This will typically be within the view of the application.

Custom exceptions will added to the following files within the ‘projectx.py’ directory.

errorsbase.py

Below is an example. All custom exceptions will be subclassed from CustomBaseException.

# General Exceptions

class CustomBaseException(Exception):
    pass

class VersionError(CustomBaseException):
    pass

class ParseError(CustomBaseException):
    pass

class ConfigError(CustomBaseException):
    pass

class InstallError(CustomBaseException):
    pass

class CustomBaseException(Exception): pass class VersionError(CustomBaseException): pass class ParseError(CustomBaseException): pass class ConfigError(CustomBaseException): pass class InstallError(CustomBaseException): pass

Subclassing allows for the base class to be caught rather then having to catch each of the exceptions. Below shows an example. It is also recommended that you do not print the contents of the exception under the general exception. This is to ensure that details of the application are not exposed to the client

try:
    do something wrong
except CustomBaseExecption, exc:
    print exc
except:
    print "General Error"

errorsdrf.py

django rest framework exceptions.

Rick Donato
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