How to store a dynamic site-wide variable - django

I have an html file which is the base,where other html documents extends.Its a static page but i want to have variable in the menu.I don't think it's wise to create a view for it,since i don't intend to let users visit the base alone.So where in my project can I store site-wide dynamic variables that can be called on any page without explicitly stating them in their views.
Thank you in advance.

For user specific variables, use session.
For global constants (not variables!), use settings.py.
For global variables, consider to store it in database so it can be multithreading & multiprocess safe.

I looked around and saw different approaches,but one that doesn't compromise the DRY philosophy the most for me is registering a tag in your project then input it in the base template.Its neater See here https://stackoverflow.com/a/21062774/6629594 for an example

Storage can take any number of places, I put mine in a stats model in the db so you get all the goodness of that (and make it easy to access in views).
I then have a context processor written as so:
#context_processors.py:
def my_custom_context_processor(request):
return {'custom_context_variable1':'foo','custom_context_variable2':'bar'}
Add this to your context processors in settings.py:
TEMPLATE_CONTEXT_PROCESSORS = (
...
"my_app.context_processors.ny_custom_context_processor",
)
Provided you use render() to render your templates you can then you can just use:
{{ custom_context_variable1 }}
to return 'foo' in your template. Obviously returning strings is for example only, you can use anything you like so long as your context processor returns a dict.

you can also try using php pages.
Then acces the variable on each page with an include 'file containing the var.php' on every page.
None of this will be visible in the source html as it is only processed on the server side.
If you you would like to try this, mail me and I will send you some sample code.

Related

Is there an HTML sanitizer library for django to block injection attacks?

I'm trying to find something that will return an exception upon finding anything that even remotely looks like HTML or Javascript. I've figured out how to do it for individual views, but it's not a scalable solution, and ultimately I need to prevent code from being saved to the database no matter what view gets targeted by the injection attack.
Here is the functionality I'm looking for.
ILLEGAL_CHARS = '<>[]{}():;,'.split()
# bunch of code in between
for value in [company_name, url, status, information, lt_type, company_source]:
if any(char in value for char in ILLEGAL_CHARS):
raise Exception(f"You passed one of several illegal characters: {ILLEGAL_CHARS}")
I'm using django rest framework so I have to handle it on the backend. Thanks.
actually you don't nead to sanitize any user input because when you show them int the template the jinja {{object}} will make sure that no html or java script will be executed until you mark them as safe {{object|safe}} but if you want want not to save them in database that might help Sanitizing HTML in submitted form data

robots.txt handling a # in a URL

Given the following URLs:
example.com/products
example.com/products#/page-2
example.com/products#/page-3
...
By using the robots.txt file, the first URL (example.com/products) is supposed to be indexed, every other one should be blocked from being indexed. How can this be done?
None of the following attempts work in the desired manner:
Noindex: /products#/page-*
Noindex: /products\#/page-*
Noindex: /*/page-*
Noindex: /*#/page-*
Noindex: /*\#/page-*
/products#/page is not a unique page. The actual url is simply /products.
# is abused to hook into javascript frameworks that dynamically load other pages, but, but normally /products#/page means that your /products page has an element such as this <a name="#/page">, and you can't block specific elements.
SPA's break the web. You're better off creating real, independent pages.
Everything after # is called "anchor". This information is NOT transferred to the server, hence you cannot read it from PHP, or any other language that is executed on the serverside.
As #Evert Outlines, the "anchor-tag" is commonly abused with javascript, as it can be modified WITHOUT the need of an actual redirect, allowing to generate deep-links, for dynamic content. (They are working, cause a client-side javascript will take care to use AJAX to dynamically load content based on the anchor-tag)

Get data from request in template django

I wonder is it a bad idea to get data from request session or is it better to parse the data into dict context and render it (Need to do it for each view)?
you can add this to your TEMPLATE_CONTEXT_PROCESSORS if you are accessing the request object in templates frequently (like I do for URL get parameter processing).
"django.core.context_processors.request",
It's common practice to send what you need through the context in the view.
I feel like it gives you a little more security/certainty in what you're doing because you can keep your logic in the view where it should be rather than doing any checks in the template for things being in the request.
edit
The above is only true if you're looking to do something rarely. If you're regularly adding an element of the request to your templates you should indeed, as everybody else suggests, be writing context processors to make what you require available to all views.
Take a look at the docs; TEMPLATE_CONTEXT_PROCESSORS
Also give this chapter of the django book a read as it'll be very helpful; Chapter 9: Advanced Templates
Specifically this section;
Guidelines for Writing Your Own Context Processors
Here are a few tips for rolling your own:
Make each context processor responsible for the smallest subset of functionality possible. It’s easy to use multiple processors, so you might as well split functionality into logical pieces for future reuse.
Keep in mind that any context processor in TEMPLATE_CONTEXT_PROCESSORS will be available in every template powered by that settings file, so try to pick variable names that are unlikely to conflict with variable names your templates might be using independently. As variable names are case-sensitive, it’s not a bad idea to use all caps for variables that a processor provides.
It doesn’t matter where on the filesystem they live, as long as they’re on your Python path so you can point to them from the TEMPLATE_CONTEXT_PROCESSORS setting. With that said, the convention is to save them in a file called context_processors.py within your app or project.
Django gives you a way to put data into every template, it is called context processors.
http://www.b-list.org/weblog/2006/jun/14/django-tips-template-context-processors/
https://docs.djangoproject.com/en/1.7/ref/templates/api/

CFInclude vs Custom Tag vs CFC for Presentation and Security

I'm just starting out with ColdFusion OOP and I am wanting to make a DIV which shows different links to users depending on what page they are on and what login rights (role) they have. Basically a 'context' menu.
Should I put this toolbar/navigation DIV in a .cfm or .cfc file?
To reiterate; The cfm or cfc file needs to know what page the user is on and will also check what role they have. Depending on these two pieces of information it will display a set of links to the user. The role information comes from the database and stored in a SESSION variable, and to find out what page they are on I guess it could use #GetFileFromPath(GetBaseTemplatePath())#.
My first thought was to have a normal .cfm file, put all the presentation and logic in that file (the HTML and lots of <cfif> statements) to ensure the correct information is displayed in the DIV, and then use <cfinclude> to display it on the page. Then I started thinking maybe I should make a Custom Tag and ask the calling page to pass in the user's credentials and the #GetFileFromPath(GetBaseTemplatePath())# as arguments and then have that Custom Tag return all the presentational data.
Finally I guess a CFC could do the above as well, but I'd be breaking the 'rule' of having presentational and logic data in a CFC.
Any suggestions on the best practice to achieve what I'm trying to do? It will eventually serve thousands of customers so I need to make sure my solution is easy to scale.
Anything that outputs HTML to the screen should be in a .cfm file.
That being said, depending on your need, you could have methods in a CFC that generate HTML, but the method simply returns the HTML as a string.
In programming, there are very few absolutes, but here is one: You should NEVER directly output anything inside of a function or method by using output="true". Instead, whatever content is generated, it should be returned from the method.
If you will have a need to use this display element more than once, a custom tag might be the best way to go rather than an include.
I see security as being a combination of what menu items I can see and what pages can be ran.
The main security function is inside of the main session object
On the menus
I call a function called
if (session.objState.checkSecurity(Section, Item) == 1)
then ...
For page security
function setupRequest() {
...
if (session.objState.checkSecurity(getSection(), getItem()) == 0) {
location("#request.self#?message=LoginExpired", "no");
return;
}
...
}
The particulars of what checkSecurity can do varies from application to application, but it is tied into how FW/1 works. The following security variations exist:
session.objState.checkSecurity(getSection())
session.objState.checkSecurity(getSection(), getItem())
session.objState.checkSecurity(getSection(), getItem(), Identifier)
None of the presentation files know anything about security.
Rules by which I live:) :
No CF business logic in CFM files. Just use some service which will serve template and provide needed data.
navService = com.foobar.services.Navigation(form, url);
and later output #navService.GetNavConent()#
No direct output from CFC files, functions should always return content. For example, make one function which makes one link based on some logic, second which wraps that and returns to cfm template.
Also one more hint, avoid using application and session scopes in your services.
This makes refactoring, testing and debugging too difficult.
For session you can make session.currentUser , CurrentUser.cfc which provides all things you need. e.g. session.currentUser.isAuthorized("backend/administration") and if true, show link to backend/administration.
Same for application, if you need locale, applicaiton wide setting or some singleton, make application.applicationSettings, ApplicationSettings.cfc and use that to retrieve all info you need in cfc's.
These rules will make your application to be easier to test and debug, and really easy to migrate tomorrow on some javascript based UI like Angular or backbone.js since all th edata you need is already in CFC and theoretically you just need to put remote in CFC or make some remote facade in the middle and you're done.

Removing query string from url in django while keeping GET information

I am working on a Django setup where I can receive a url containining a query string as part of a GET. I would like to be able to process the data provided in the query string and return a page that is adjusted for that data but does not contain the query string in the URL.
Ordinarily I would just use reverse(), but I am not sure how to apply it in this case. Here are the details of the situation:
Example URL: .../test/123/?list_options=1&list_options=2&list_options=3
urls.py
urlpatterns = patterns('',
url(r'test/(P<testrun_id>\d+)/'), views.testrun, name='testrun')
)
views.py
def testrun(request, testrun_id):
if 'list_options' in request.GET.keys():
lopt = request.GET.getlist('list_options')
:
:
[process lopt list]
:
:
:
:
[other processing]
:
:
context = { ...stuff... }
return render(request, 'test_tracker/testview.html', context)
When the example URL is processed, Django will return the page I want but with the URL still containing the query string on the end. The standard way of stripping off the unwanted query string would be to return the testrun function with return HttpResponseRedirect(reverse('testrun', args=(testrun_id,))). However, if I do that here then I'm going to get an infinite loop through the testrun function. Furthermore, I am unsure if the list_options data that was on the original request will still be available after the redirect given that it has been removed from the URL.
How should I work around this? I can see that it might make sense to move the parsing of the list_options variable out into a separate function to avoid the infinite recursion, but I'm afraid that it will lose me the list_options data from the request if I do it that way. Is there a neat way of simultaneously lopping the query string off the end of the URL and returning the page I want in one place so I can avoid having separate things out into multiple functions?
EDIT: A little bit of extra background, since there have been a couple of "Why would you want to do this?" queries.
The website I'm designing is to report on the results of various tests of the software I'm working on. This particular page is for reporting on the results of a single test, and often I will link to it from a bigger list of tests.
The list_options array is a way of specifying the other tests in the list I have just come from. This allows me to populate a drop-down menu with other relevant tests to allow me to easily switch between them.
As such, I could easily end up passing in 15-20 different values and creating huge URLs, which I'd like to avoid. The page is designed to have a default set of other tests to fill in the menu in question if I don't suggest any others in the URL, so it's not a big deal if I remove the list_options. If the user wishes to come back to the page directly he won't care about the other tests in the list, so it's not a problem if that information is not available.
First a word of caution. This is probably not a good idea to do for various reasons:
Bookmarking. Imagine that .../link?q=bar&order=foo will filter some search results and also sort the results in particular order. If you will automatically strip out the querystring, then you will effectively disallow users to bookmark specific search queries.
Tests. Any time you add any automation, things can and will probably go wrong in ways you never imagined. It is always better to stick with simple yet effective approaches since they are widely used thus are less error-prone. Ill give an example for this below.
Maintenance. This is not a standard behavior model therefore this will make maintenance harder for future developers since first they will have to understand first what is going on.
If you still want to achieve this, one of the simplest methods is to use sessions. The idea is that when there is a querystring, you save its contents into a session and then you retrieve it later on when there is no querystring. For example:
def testrun(request, testrun_id):
# save the get data
if request.META['QUERY_STRING']:
request.session['testrun_get'] = request.GET
# the following will not have querystring hence no infinite loop
return HttpResponseRedirect(reverse('testrun', args=(testrun_id,)))
# there is no querystring so retreive it from session
# however someone could visit the url without the querystring
# without visiting the querystring version first hence
# you have to test for it
get_data = request.session.get('testrun_get', None)
if get_data:
if 'list_options' in get_data.keys():
...
else:
# do some default option
...
context = { ...stuff... }
return render(request, 'test_tracker/testview.html', context)
That should work however it can break rather easily and there is no way to easily fix it. This should illustrate the second bullet from above. For example, imagine a user wants to compare two search queries side-by-side. So he will try to visit .../link?q=bar&order=foo and `.../link?q=cat&order=dog in different tabs of the same browser. So far so good because each page will open correct results however as soon as the user will try to refresh the first opened tab, he will get results from the second tab since that is what is currently stored in the session and because browser will have a single session token for both tabs.
Even if you will find some other method to achieve what you want without using sessions, I imagine that you will encounter similar issues because HTTP is stateless hence you will have to store state on the server.
There is actually a way to do this without breaking much of the functionality - store state on client instead of server-side. So you will have a url without a querystring and then let javascript query some API for whatever you will need to display on that page. That however will force you to make some sort of API and use some javascript which does not exactly fall into the scope of your question. So it is possible to do cleanly however that will involve more than just using Django.