I am wondering on how to implement pure controller functions in a Django's' "biased" MVC scheme. Let me explain it on an example.
Let's say I have a model of an Invoice, which has some attributes (say net, gross etc.). I can present it to the user using a view + template. And that's fine and easy.
But now, I want to send this invoice to a client. This is a more complicated thing, inluding more models (i.e. create an addressed Package model, get a number and let's say few other thing including creating and modifying not only Invoice model itself, but also creating and updating few other model types and instances.
I want this "action" to be available in multiple places of my web application, so going by the book I need to create a view with those actions implemented and bind it to some URL. Probably it should be implemented in POST action.
My questions are:
What kind of generic view should it be (just View? DetailView? other?).
Where should this View redirect after succesfull "send"? The simplest answer would be to redirect to the same referring page, but is this a correct way?
What if I want this "action" to be ran in background (say, send all unsend invoices at midnight) using celery or such? Of course I can make this a celery task and call it in a view. But is this clean django'ish solution? Where do you store such pure business methods in an app/project?
Related
I've been searching stack overflow and google for a solution for over an hour now, and I can't seem to find something that, in my opinion, should be easy to obtain (as it's a common use case).
I've checked this thread, and a few others, but I haven't been able to find a real, easy solution:
Django modelform: is inline adding related model possible?
Anyway, say I have a model with three related entities, two foreign keys and a many-to-many related class. Now, I have a ModelForm which displays these in comboboxes and lists, but what I need is that "+" button next to these elements (as seen in the admin interface).
I want the plus to take me to a new form, for that particular entity, allow me to submit the new information, create the database entry, take me back to my original form and have the newly added entity selected in the combobox. I'm really hoping the django ModelForm Meta class has an attribute that I can't seem to find which enables exactly this.
This isn't really a django question.
This has to do with presentation of a particular widget in an html document, and that is governed by either the HTML markup, CSS, or javascript.
Django is a server side application and is primarily responsible for creating a valid http response and receiving a valid http request (of course, there is a lot that happens in the interim and that is why django is so big) but it's not a "one toolkit to kill them all" app.
I think you want to look at bootstrap: http://getbootstrap.com/
Jquery UI: http://jqueryui.com/
Or some combination of the two.
You can also just mark up the document yourself with a stock img or something.
However, if you want to do it exactly how the admin does it, just go into django.contrib.admin and examin the code to figure out how the django developers did it. I believe they are just using Jquery UI and some manual markup to accomplish that.
I am using python and django and like it a lot. But than i use it, I catch myself thinking
what i do a lot of work to render result data and write specific actions for it. For example than i pass result set of objects to template
i must render all data and write all possible actions such as sorting by columns,filtering,deletion,edit etc, for each of this i need
to write code in urls.py and views.py, sometimes helps generic view but it's has poor functions.
Is there some solutions to automate this work?
i mean use some interface compontents (such as "model list renderer with column filter and pagination") to wich i need only
"bind my model", all other routing work for drawing common interface action must be allready implemented in these components.
i think i need something like configurable components for fast building html web interface for models (such as model forms do fast generation forms for models).
What do you think can help in this case?
must render all data and write all
possible actions such as sorting by
columns,filtering,deletion,edit etc
Like django.contrib.admin? But I guess it's way to complicated and bloated for your needs.
sometimes helps generic view but it's
has poor functions
And that's the way, I think, you should be going. If you write same views over and over again, just make your own generic views. As an example of more robust views and a source of inspiration I recommend you to look at class-based generic views.
Also consider using model inheritance and custom managers.
I am currently writing an application which I plan to sell as SaaS. Without giving away "secrets," I can say that it is basically a "document editing system" in which many users will be submitting documents.
The basic heirarchy is this:
Institution
Individual
Document
Sub-document
So each Individual should be able to BROWSE all documents that were submitted by anybody in their institution, but should only be able to EDIT documents that they created.
No individual should even be aware of the existence of another Institution--that should all be completely hidden.
I have written a Django/Python class that would facilitate this, but every document regarding authentication that I have read requires that I use the User object. Is this just a limitation of Django, or is there a way to do this?
If there is a way, how can I get my own "Individual" class details attached to the "request" objects so I can validate the things I should be showing the users?
What you're looking for is authorization, not authentication. Django's built-in authorization system is fairly crude, as you've discovered. You'll need something like django-authority if you want a more complete solution.
The auth module is typically used to cover authentication cases.
Gives you groups (Institutions), Users (Individuals) and permissions.
Using these features you can perform checking if a user is a member of a group or owns a doc before allowing them to see or edit the doc.
http://docs.djangoproject.com/en/dev/topics/auth/
If you need to go beyond the typical use case, supporting LDAP for example, then you can look at writing your own authentication backend.
http://docs.djangoproject.com/en/dev/topics/auth/#other-authentication-sources
In general, if you need to attach more information to the builtin User model, you would create new model which subclasses models.Model (not User), and identify it in settings as AUTH_PROFILE_MODULE. You can get the appropriate instance of your model from a user by calling user.get_profile(). (see http://docs.djangoproject.com/en/dev/topics/auth/#storing-additional-information-about-users).
This is generally useful for adding extra fields to User such as address, contact information, etc. While it would be possible to use this for your authentication needs, you'd most likely be better off using the built in groups, or a more comprehensive solution like django-authority as others have mentioned. I've included this answer only because it seems to be what you were asking for (a way to attach a class to User), but not really what you need (authorization).
I am adding MetaWeblog API support to a Django CMS, and am not quite sure how to layer the application.
I am using django_xmlrpc, which allows me to map to parameterised functions for each request. It is just a case of what level do I hook in calls to the django application from the service functions (AddPage, EditPage etc)
For django-page-cms, and I suppose many django apps, the business logic and validation is contained within the forms. In this case there is PageForm(forms.ModelForm) and PageAdmin(ModelAdmin), which both contain a lot of logic and validation.
If I am to build an API to allow maintenance of pages and content, does this mean I should be programmatically creating and filling a PageAdmin instance? Then catching any exceptions, and converting to their api equivalent? Or would this be a bad idea - misusing what forms are intended for?
The other option is refactoring the code so that business and logic is kept outside of the form classes. Then I would have the form and api, both go through the separate business logic.
Any other alternatives?
What would be the best solution?
Web services API's are just more URL's.
These WS API URL's map to view functions.
The WS view functions handle GET and POST (and possibly PUT and DELETE).
The WS view functions use Forms as well as the Models to make things happen.
It is, in a way, like an admin interface. Except, there's no HTML.
The WS view functions respond with JSON messages or XML messages.
It seems python does not provide this out of the box. But there is something called abc module:
I quote from http://www.doughellmann.com/PyMOTW/abc/ "By defining an abstract base class, you can define a common API for a set of subclasses. This capability is especially useful in situations where a third-party is going to provide implementations..." => the goal of an API, defining a contract.
Pretty new to this scene and trying to find some documentation to adopt best practices. We're building a fairly large content site which will consist of various media catalogs and I'm trying to find some comparable data / architectural models so that we can get a better idea of the approach we should use using a framework we've never made use of before. Any insight / help would be greatly appreciated!
"data / architectural models so that we can get a better idea of the approach we should use using a framework we've never made use of before"
Django imposes best practices on you. You don't have a lot of choices and can't make a lot of mistakes.
MVC (while a noble aspiration) is implemented as follows:
Data is defined in "models.py" files using the Django ORM models.
urls.py file maps URL to view function. Pick your URL's wisely.
View function does all processing, making use of models and methods in models
Presentation (via HTML templates) invoked by View function. Essentially no processing can be done in presentation, just lightweight iteration and decision-making
The model is defined for you. Just stick to what Django does naturally and you'll be happy.
Architecturally, you usually have a stack like this.
Apache does two things.
serves static content directly and immediately
hands dynamic URL to Django (via mod_python, mod_wsgi or mod_fastcgi). Django apps map URL to view functions (which access to database (via ORM/model) and display via templates.
Database used by Django view functions.
The architecture is well-defined for you. Just stick to what Django does naturally and you'll be happy.
Feel free to read the Django documentation. It's excellent; perhaps the best there is.
first, forget all MVC mantra. it's important to have a good layered structure, but MVC (as defined originally) isn't one, it was a modular structure, where each GUI module is split in these tree submodules. nothing to use on the web here.
in web development, it really pays to have a layered structure, where the most important layer is the storage/modelling one, which came to be called model layer. on top of that, you need a few other layers but they're really not anything like views and controllers in the GUI world.
the Django layers are roughly:
storage/modelling: models.py, obviously. try to put most of the 'working' concepts there. all the relationships, all the operations should be implemented here.
dispatching: mostly in urls.py. here you turn your URL scheme into code paths. think of it like a big switch() statement. try hard to have readable URLs, which map into user intentions. it will help a lot to add new functionality, or new ways to do the same things (like an AJAX UI later).
gathering: mostly the view functions, both yours and the prebuilt generic views. here you simply gather all the from the models to satisfy a user request. in surprisingly many cases, it just have to pick a single model instance, and everything else can be retrieved from relationships. for these URLs, a generic view is enough.
presentation: the templates. if the view gives you the data you need, it's simple enough to turn it into a webpage. it's here where you'll thank that the model classes have good accessors to get any kind of relevant data from any given instance.
To understand django fundementals and the django take on MVC, consult the following:
http://www.djangobook.com/
As a starting point to getting your hands dirty with ...
"...trying to find some comparable data / architectural models"
Here is a quick and dirty way to reverse engineer a database to get a models.py file,
which you can then inspect to see how django would handle it.
1.) get an er diagram that closely matches your target. For example something like this
http://www.databaseanswers.org/data_models/product_catalogs/index.htm
2.) create an sql script from the er diagram and create the database,
I suggest Postgre, as some MySQL
table type will not have forgien key constraints, but in a pinch MySQL or SQLITE
will do
3.) create and configure a django app to use that database. Then run:
python manage.py inspectdb
This will at least give you a models.py file which you can read to see how django attempts
to model it.
Note that the inspect command is intended to be a shortcut for dealing with legacy
database when developing in django, and as such is not perfect. Be sure to read the
following before attempting this:
http://docs.djangoproject.com/en/dev/ref/django-admin/#ref-django-admin