Trigger my function when any file is saved in django

I would like to tap on file save event inside my Django application

I have dockerized Django application. When I press save in any file, the server is restarted and docker image rebuild.

I would like similar functionality: Whenever I press save in any file, I would like that my function is called after server is rebooted.

How to achieve this behaviour.

I try with overriding FileSystemStorage but it's not working.

from django.core.files.storage import FileSystemStorage
    

class CustomFileSystemStorage(FileSystemStorage):
    def _save(self, name, content):
        saved_file_name = super()._save(name, content)
        self.my_custom_function(saved_file_name, name, content)
    
        return saved_file_name

    def my_custom_function(self, file_path, name, content):
        print('File saved at: ', file_path)
        print('File name: ', name)
        print('File content: ', content)

settings.py:

DEFAULT_FILE_STORAGE = 'myApp.storage.CustomFileSystemStorage'

When I save file nothing is logged

Not a solution:

trigger when file is saved programmatically
trigger when model object is saved

Edit:

By press save on ant file I mean press cmd+s on a file that I was editing (for example: test.py)

Any change on disk results in rebuilding the docker image. I would like to do similar that they did.

EDIT 2:

I thought that because on save server is restarted and docker image rebuild... maybe there is a way to tap on those triggers.

Can I trigger my function when server is restarted? But there would probably be difficult to get a file that was changed...

EDIT 3:

My apps.py

from django.apps import AppConfig
import logging


class MyAppConfig(AppConfig):
    default_auto_field = 'django.db.models.BigAutoField'
    name = 'myApp'

    def ready(self):
        logger = logging.getLogger(__name__)
        logger.info("READY 123123")

I also try

from django.apps import AppConfig
import logging


class MyAppConfig(AppConfig):
    default_auto_field = 'django.db.models.BigAutoField'
    name = 'myApp'

    def ready(self):
        print('TEST')

The settings.py

"""
Django settings for WisdomCore project.

Generated by 'django-admin startproject' using Django 4.2.

For more information on this file, see
https://docs.djangoproject.com/en/4.2/topics/settings/

For the full list of settings and their values, see
https://docs.djangoproject.com/en/4.2/ref/settings/
"""

from pathlib import Path

# Build paths inside the project like this: BASE_DIR / 'subdir'.
BASE_DIR = Path(__file__).resolve().parent.parent


# Quick-start development settings - unsuitable for production
# See https://docs.djangoproject.com/en/4.2/howto/deployment/checklist/

# SECURITY WARNING: keep the secret key used in production secret!
SECRET_KEY = 'xxx'

# SECURITY WARNING: don't run with debug turned on in production!
DEBUG = True

ALLOWED_HOSTS = []


# Application definition

INSTALLED_APPS = [
    'django.contrib.admin',
    'django.contrib.auth',
    'django.contrib.contenttypes',
    'django.contrib.sessions',
    'django.contrib.messages',
    'django.contrib.staticfiles',
    'my_app'
]

MIDDLEWARE = [
    'django.middleware.security.SecurityMiddleware',
    'django.contrib.sessions.middleware.SessionMiddleware',
    'django.middleware.common.CommonMiddleware',
    'django.middleware.csrf.CsrfViewMiddleware',
    'django.contrib.auth.middleware.AuthenticationMiddleware',
    'django.contrib.messages.middleware.MessageMiddleware',
    'django.middleware.clickjacking.XFrameOptionsMiddleware',
]

ROOT_URLCONF = 'Projects.urls'

TEMPLATES = [
    {
        'BACKEND': 'django.template.backends.django.DjangoTemplates',
        'DIRS': [],
        'APP_DIRS': True,
        'OPTIONS': {
            'context_processors': [
                'django.template.context_processors.debug',
                'django.template.context_processors.request',
                'django.contrib.auth.context_processors.auth',
                'django.contrib.messages.context_processors.messages',
            ],
        },
    },
]

WSGI_APPLICATION = 'Project.wsgi.application'


# Database
# https://docs.djangoproject.com/en/4.2/ref/settings/#databases

DATABASES = {
    'default': {
        'ENGINE': 'django.db.backends.sqlite3',
        'NAME': BASE_DIR / 'db.sqlite3',
    }
}


# Password validation
# https://docs.djangoproject.com/en/4.2/ref/settings/#auth-password-validators

AUTH_PASSWORD_VALIDATORS = [
    {
        'NAME': 'django.contrib.auth.password_validation.UserAttributeSimilarityValidator',
    },
    {
        'NAME': 'django.contrib.auth.password_validation.MinimumLengthValidator',
    },
    {
        'NAME': 'django.contrib.auth.password_validation.CommonPasswordValidator',
    },
    {
        'NAME': 'django.contrib.auth.password_validation.NumericPasswordValidator',
    },
]


# Internationalization
# https://docs.djangoproject.com/en/4.2/topics/i18n/

LANGUAGE_CODE = 'en-us'

TIME_ZONE = 'UTC'

USE_I18N = True

USE_TZ = True


# Static files (CSS, JavaScript, Images)
# https://docs.djangoproject.com/en/4.2/howto/static-files/

STATIC_URL = 'static/'

# Default primary key field type
# https://docs.djangoproject.com/en/4.2/ref/settings/#default-auto-field

DEFAULT_AUTO_FIELD = 'django.db.models.BigAutoField'


LOGGING = {
    'version': 1,
    'disable_existing_loggers': False,
    'handlers': {
        'console': {
            'class': 'logging.StreamHandler',
        },
    },
    'loggers': {
        'django': {
            'level': 'INFO',
            'handlers': ['console'],
            'propagate': True,
        },
        'django.db.backends': {
            'handlers': ['console'],
            'level': 'DEBUG',
            'propagate': True,
        }
    },
}

The logs are:

I don't have any other code...

My tree

├── Dockerfile
├── Project
│   ├── __init__.py
│   ├── asgi.py
│   ├── settings.py
│   ├── urls.py
│   └── wsgi.py
├── docker-compose.yml
├── my_app
│   ├── __init__.py
│   ├── admin.py
│   ├── apps.py
│   ├── migrations
│   │   └── __init__.py
│   ├── models.py
│   ├── tests.py
│   └── views.py
├── install.sh
├── local_settings.py
├── makefile
├── manage.py
├── neo4j-conf
│   └── neo4j.conf
├── neo4j_data
└── requirements.txt

Solution

Thank you all for the great suggestions that lead me to the correct answer.

Detect server restart

Similar to @Daviid suggestion, I solve this by AppConfig

Create a management command that contains the code you would like to run

# commands/startup_actions.py
from django.core.management.base import BaseCommand

class Command(BaseCommand):
    help = 'Actions to perform on server startup or app ready'

    def handle(self, *args, **options):
        # Put your startup actions here, similar to what you would have done in AppConfig.ready
        print("Server is starting up or app is ready.")

Call this method inside AppConfig:

from django.apps import AppConfig


class MyAppConfig(AppConfig):
    default_auto_field = 'django.db.models.BigAutoField'
    name = 'myApp'

    def ready(self):
        # Run the custom management command on server startup
        from django.core.management import call_command
        call_command('startup_actions')

This actually works and prints "Server is starting up or app is ready." on file save.

But: You need to figure out which file has changed by yourselves.

Detect file change

You can use the watchdog library to detect which file has been changed

Pip install watchdog:
```
pip install watchdog==3.0.0
```

also put it inside requirement.txt

Create a file_observer.py file on the root directory

# file_observer.py

import time
from watchdog.observers import Observer
from watchdog.events import FileSystemEventHandler, RegexMatchingEventHandler

from graph_parser.parser import CypherMethodParser


class MyHandler(RegexMatchingEventHandler):
    def on_modified(self, event):
        if event.is_directory:
            return
        # This function will be called when a file is modified
        print(f"File {event.src_path} has been modified with {event} event.")
        # Sometimes this is called 2 times in a row. To prevent this put sleep
        time.sleep(1)

def start_observer():
    event_handler = MyHandler(regexes=[r'.*\.py$', r'.*\.csv$'])
    observer = Observer()
    observer.schedule(event_handler, path='.', recursive=True)
    observer.start()
    try:
        while True:
            time.sleep(1)
    except KeyboardInterrupt:
        observer.stop()
    observer.join()


if __name__ == "__main__":
    start_observer()

Inside the install.sh (or where you install requirements.txt in your docker container...) add

pip install --upgrade pip
pip install -r requirements.txt
python file_observer.py &        # <--- this is the new line