I was reading some blogs and came up to the conclusion that django is an MVT architecture which do not maintain state. I am working on application that have maps visualization. When the user selects a variable from the drop down, a request is sent to the backend database and on the screen, it generates the heat-map of that specific variable.
what I want to achieve is that if I go some other tab and do some other changes like change the layer of map or select some another variable, the state of old heat map should be maintained regardless if I want to clear it. I do not know how to maintain state in django can anyone help me in this?
You can leverage the Django's sessions mechanism. You'll need an AJAX request that POSTs the current tab state to Django, so your backend code can restore it on page reload.
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I have an existing Django project in the sports domain with apps that are built on the Model-View-Template structure. Many of the models and views are fairly sophisticated and work well currently. Data from the database (scores etc) is combined with some incoming user inputs through forms (HTTP POST requests) to be displayed on a web page via templates.
However, I now need live data to be displayed to users and be automatically refreshed to all the users continuously, either because one of the users entered something new (in the front-end), or because the scores changed during the game (directly enters the back-end).
I've done some research on Stack Overflow as well as tutorials on Youtube/ rest of the web and it appears that for me to use Django Channels, I'd have to start from scratch and build everything ground-up, which I'd like to avoid. How do I use the websocket protocol for my Django app easily without having to completely rework everything that I've done so far?
You don't really need to start from scratch or anything. You just need to add a module using channels. I am assuming that currently, the data is fetched only when the page is refreshed. What you need to do is write a consumer that is used to send messages directly to the client via websocket. Then in the front you can update the widget with the scores on each message received in the websocket. You can also stream user actions through the websocket to the server which will then be broadcasted by the consumer to needed clients. You may not even need to change anything in the existing code.
It will be easier to understand how this works and how you can incorporate it to your project by reading the channels tutorials. It became clearer to me after reading it so I would advice you do the same
Folks,
I am pretty sure I am not the first one to stumble on this problem. But somehow I am unable to find any relevant resources out there.
Here is my issue, I have a backend in Django and my front completely written in Reactjs- React Router - Redux (nice combo right).
when entering the url webhost.com/, django provides me with a page with links to a bundle that is my whole react application and different stylesheets
The problem arise when I want to refresh a page, the browser still tries to query the server even though a route exists in my react-router configuration.
I had a look at the answer here (catch-all option) React-router urls don't work when refreshing or writting manually , but I don't quite understand it and I am afraid to have a new redux state everytime Django will provide the user with a new page.
You can setup up a wildcard url pattern that will render the same view that gets rendered when a request is sent to webhost.com. I don't know if that's going to retain your store though.
My question is, is there a way to maintain the context object over multiple views? Say you are at the home page, you click a link to go to a specific part of the application but you want to maintain the context information as to not excessively query the DB for this information every time you change views.
I know of mixins and such, but these do not seem to maintain the information, or am I wrong? Question is, can I access the context information and pass it to the next view?
In order to maintain state across views, you can use django sessions.
The session framework lets you store and retrieve arbitrary data on a per-site-visitor basis.
You have to enable the session middleware and add the appropriate settings. Once you do, you will have to manually add code to each view to check to see if the session has information related to that view’s context and to update the session with the data from the context.
My django app needs to display data on my homepage which it collected from third party. Requesting the information and waiting for response takes about a second, which is too long processing time for a homepage. The data which my app receives doesn't change often, so there is no reason to fetch that data every time homepage is being rendered. Instead, I want to retain the data and have my app make a request only if the last "refresh" has been done more than an hour ago.
Since using global variables in django is apparently a no-no, I'd need to make a database model which will at all times hold a single record. This feels wrong. Is making a one-record table really a way to go here?
Instead of creating a model to cache the remote site's response, you can use Django's caching framework. More specifically, you can cache a specific view and set a timeout for the cached view. See this documentation page for more details on how to do that.
I'm using django-registration to log users into my application. That part works fine. The part that I cannot figure out is how to set custom session variables when the user logs in. For instance, I'd like to populate variables containing UserProfile data as well as the output of a few other functions. Then I'd be able to use that information in subsequent views/templates.
If anybody can point me to a tutorial online or post some sample code, that would be great.
I'm using django 1.1 and Python 2.6
If you don't want persistent storage of user data (just additional session data) have a look at:
http://docs.djangoproject.com/en/dev/topics/http/sessions/
The sessions framework will most probably be already enabled if you use django.contrib.auth.
If you want persistent storage of additional user data (not only in a session, but in the database), you will store them in another "profile" model:
http://docs.djangoproject.com/en/dev/topics/auth/#storing-additional-information-about-users
I realize #stefanw provided you an alternative solution, but to answer the original question:
Setting session data at login is difficult because the easiest place to set that data is in your view function, and the particular view function you'd want to modify is a part of the contrib.django.auth app.
So your options would be the following:
Create a small middleware class to set your session data.
Create a template tag or other bit of code than can be integrated into the login template or subsequent page that will set the data you want.
Write your own custom login view function (it's really quite easy, actually).
Happy django-ing!