Flash Messages in Django

gistfile1.md

#Flash messages

DOCUMENTATION

###RECAP: One time messages. "Allows you to store messages in one request & retrieve them for display in a subsequent(usually next) request"

###Overview In django, flashed messages are part of the messages app that is included in the generic django-admin startproject command. When used, a message object is added to the request object(via session/cookie) that is readily available for use in views or templates in subsequent requests. Each flash message is an instance of the Message class which has the following attributes:

• message: the actual message's text
• level: integer representation of message level
• tags: string that combines messages extra and level tags space-delimited
• extra_tags: custom string tags for this message
• level_tag: string tag representing level

In regular use, only the message, tags, and extra_tags are going to be directly interacted with. For more on the level and level_tag attributes, see below. What's important to note here is that you can effectively categorize your messages using the extra_tags.

Regular use of flash messages is pretty open ended. The most common cases are to use it for alerting users of form field errors, success messages, warnings, and errors. To reiterate, anytime you need to alert a user of something hopefully only once, a flash message is great, effective method.

###Usage In your views:

from django.contrib import messages

Creation: you can add a message to be flashed by using this handy-dandy little line:

messages.add_message(request, messages.INFO, 'yourmessagehere')

If you are using a default message-level, youcan use: messages.(request, 'yourmessagehere')

Display: you can view a requests messages

from django.contrib.messages import get_messages

memos = get_messages(request)
for message in memos:
	...message...

Display in template:

• Step 1: check if messages

• Step 2: ITERATE through messages. Iteration clears the messages from storage

• This example prints each message and any tags associated with it

    {% if messages %}
    	{% for message in messages %}
    		<p>{{ message }} 
    			{% if message.tags %}
    			has these tags: {{message.tags }}
    			{% endif %}</p>
    	{% endfor %}
    {% endif %}
  

Flash messages with form: When you used bound forms, django will take care of field-error flashing. However, if you wish to do it by hand or alter how it is normally handled you certainly can. Additionally, there may be non-field specific errors associated with your form that you can handle with non-field errors. To learn more about handling specific field errors check out the docs on manually rendering fields or the docs on how forms handle errors. The gist of it is to use bound forms because django saves you a lot of work.

###Next Level... Message Level: Messages have a level attribute that serves as a way to exclude certain types of messages from showing up. Each request has a minimum level that can be set in the views. An example of this is that in development, you can see debugging messages, but when you deploy the minimum level will be changed so that debug(the lowest level) messages won't be displayed. As with most things in django, these levels can be customized and added to, but it is recommended that if you are making a reusable app, don't customize these. For deeper information on levels, I once again refer you to the docs

An overview of the built in message-levels

level	level_tag	int value
DEBUG	debug	10
INFO	info	20
SUCCESS	success	25
WARNING	warning	30
ERROR	error	40