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Django - Messages

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• Django - Messages
  • Enabling messages
  • Message
    • Message levels
    • Message tags
    • Message class
  • Usage
    • Template
    • Views
    • Class-based views: SuccessMessageMixin

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Enabling messages

• To enable message functionality, by default, the following should be contained in settings.py:
  • INSTALLED_APPS:
    • 'django.contrib.messages'
  • MIDDLEWARE:
    • 'django.contrib.sessions.middleware.SessionMiddleware'
    • 'django.contrib.messages.middleware.MessageMiddleware'. Should be after SessionMiddleware.
  • TEMPLATES’s 'context_processors' option:
    • 'django.contrib.messages.context_processors.messages'

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Message

Message levels

• django.contrib.messages module

Constant	Purpose	Value
DEBUG	Development-related messages, will be ignored (or removed) in a production deployment	10
INFO	Informational messages for the user	20
SUCCESS	An action was successful	25
WARNING	A failure did not occur but may be imminent	30
ERROR	An action was not successful or some other failure occurred	40

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Message tags

• Message tags:
  • a string representation of the message level plus any extra tags that were added directly in the view.
• Tags are stored in a string and are separated by spaces.

Level Constant	Tag
DEBUG	debug
INFO	info
SUCCESS	success
WARNING	warning
ERROR	error

• To change the default tags for a message level (either built-in or custom), set the MESSAGE_TAGS setting to a dictionary containing the levels you wish to change.

from django.contrib.messages import constants as messages

MESSAGE_TAGS = {
    messages.INFO: "",
    50: "critical",
}

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Message class

• Attributes

Attributes	Description
message	The actual text of the message
level	An integer describing the type of the message.
level_tag	The string representation of the level.
extra_tags	A string containing custom tags for this message, separated by spaces.
tags	A string combining all the message’s tags separated by spaces.

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Usage

Template

• Even if there is only one message, should still iterate over the messages sequence, because otherwise the message storage will not be cleared for the next request.

// if messages \\
<ul class="messages">
    // for message in messages \\
    <li // if message.tags \\ class="__ message.tags __"// endif \\>__ message __</li>
    // endfor \\
</ul>
// endif \\

• DEFAULT_MESSAGE_LEVELS variable: a mapping of the message level names to their numeric value

// if message.level == DEFAULT_MESSAGE_LEVELS.ERROR \\Important: // endif \\

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Views

• Adding a message

from django.contrib import messages

# using add_message
messages.add_message(request, messages.INFO, "Hello world.")    

# shortcut
messages.debug(request, "%s SQL statements were executed." % count)
messages.info(request, "Three credits remain in your account.")
messages.success(request, "Profile details updated.")
messages.warning(request, "Your account expires in three days.")
messages.error(request, "Document deleted.")

• Getting a message from request

from django.contrib.messages import get_messages

storage = get_messages(request)
for message in storage:
    do_something_with_the_message(message)

• Adding extra message tags

messages.add_message(request, messages.INFO, "Over 9000!", extra_tags="dragonball")
messages.error(request, "Email box full", extra_tags="email")

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Class-based views: SuccessMessageMixin

• SuccessMessageMixin:
  • a class adding a success message attribute to FormView based classes
• SuccessMessageMixin should be place before CreateView.

from django.contrib.messages.views import SuccessMessageMixin
from django.views.generic.edit import CreateView
from myapp.models import Author

class AuthorCreateView(SuccessMessageMixin, CreateView):
    model = Author
    success_url = "/success/"
    success_message = "%(name)s was created successfully"   # %(field_name)s syntax.

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