General knowledge

url in css:

  • Because css is a static file, so the url inside is better be static as well. so just use relative url for url() in css files.
  • for some reason it’s slow to load a file when you pupdate it in css. sometime I have to restart the local server for it to take effect

Django

  • where should signal.py file lives:

    article by Vitor Freitas & Django official doc

    1. create signal.py file in the same directory as models.py and urls.py etc.
    2. edit the file, write your code
    3. add following code in apps.py file under the same directory 
        def ready(self):
   import appName.signals # noqa
    4. register in settings.py, in INSTALLED_APPS, register 'appName.apps.appNameConfig', for signal.py to work properly

follow the four steps

  • models - DateTimeField(auto_now=True) and DateTimeField(auto_now_add=True)

    • DateTimeField(auto_now=True) – update everytime this model instance is edited
    • DateTimeField(auto_now_add=True) – set the time once when this model instance is created

  • context processor

    • adding a context processor to your project if you find repetitive bahavior in passing the same context to different views:
      1. in the same directory of models.py create a file named context_processors.py 2. create a function: ```python from .models import Category from django.template.context_processors import request

    def category_context_processor(request): categories = Category.objects.all() return {‘categories’: categories}

      3. add this processor to `settings.py`
  ```python
  TEMPLATES = [
  {
      'BACKEND': 'django.template.backends.django.DjangoTemplates',
      'DIRS': [os.path.join(BASE_DIR, 'templates')],
      'APP_DIRS': True,
      'OPTIONS': {
          'context_processors': [
              ... # other processors
              ... # add code below:<app-name>.<file-name>.<function-name>
              'app-name.context_processors.category_context_processor',
          		],
      		},
  		},
      ]

    Now you don’t have to pass categories to each view now! And this code will run on every request on the site.