Develop Reference

Where to Start with Custom Reporting Python/Django

I'm trying to find a way to build a robust report library that I can use with a Django project.
Essentially, what I'm looking for is a way to access a list of functions(reports) that I can allow an end-user to attach to a Django model.
For example, let's say I have an Employee object. Well, I have a module called reports.py that has a growing list of possible reports that take an employee object and output a report, usually in JSON form. There might be number of timecards submitted, number of supervisions created, etc.
I want to be able to link those changing report lists to the Employee object via a FK called (job description), so admins can create custom reports per job description.
What I've tried:
Direct model methods: good for some things, but it requires a programmer to call them in a template or via API to generate some output. Since the available reports are changing, I don't want to hard-code anything and would rather allow the end-user to choose from a list of available reports and attach them to a related model (say a JobDescription).
dir(reports): I could offer up a form where the select values are the results from dir(reports), but then I'd get the names of variables/libraries called in the file, not just a list of available reports
Am I missing something? Is there a way to create a custom class from which I can call all methods available? Where would I even start with that type of architecture?
I really appreciate any sort of input re: the path to take. Really just a 'look in this direction' response would be really appreciated.

What I would do is expand on your dir(reports) idea and create a dynamically loaded module system. Have a folder with .py files containing module classes. Here's an example of how you can dynamically load classes in Python.
Each class would have a static function called getReportName() so you could show something readable to the user, and a member function createReport(self, myModel) which gets the model and does it's magic on it.
And then just show all the possible reports to the user, user selects one and you run the createReport on the selected class.
In the future you might think about having different report folders for different models, and this too should be possible by reflection using model's __name__ attribute.

Django - passing user related information to many views

I would like to view some user information on over half of my website's views.
This information should contain not only trivial username but also some fields from other tables of my project that are associated with current user.
I would also like to put this information into the template that my current view extends, just to keep it DRY.
I already did some research and coded some templatetags hoping that registering tags would help me achieve this but I have no idea how to get user information when there's no request like in views' functions.
Any tips on how to achieve this will be much appreciated. I just started django yesterday and am still a bit confused by it's philosophy.

You can use a context processor to add data to the template context in a DRY way.
In a nutshell, a context processor is simply a function that accepts a request as its first argument, does some additional processing that you add and augments the context with whatever values you want.
You can query an objects models, add the current datetime...pretty much anything you can do with Python or Django can go into a context processor.

How to print textfield's value in Django and Python?

I'm trying to create a very simple web page with 2 textfields, 1 button and 3 labels to make it look like so:
First Name: [..........] <-- label + textfield
Last Name: [...........] <-- label + textfield
(Submit) <-- button
{Your full name is %FirstName% + %LastName% } <-- label
As you can see it's an extremely simple task. I could have easily done this in ASP.NET in 5 minutes but I am not very familiar with Django or Python, as I am just starting to learn the framework.
Thanks.

zomboid's comment is correct. It looks like you need to learn more about Django. You might want to take a look at this chapter from The Django Book. That text is a bit outdated, but the fundamentals are the same.
Some general guidance: you need to point a URL (e.g., /namegrabber) to a view function. Inside that view function, you decide whether the user's doing a GET or a POST. If it's a GET, then instantiate an unbound form -- i.e., a form with no data -- and pass it to a template to be rendered. If it's a POST, then instantiate your form, populating it with request.POST. Then, take the data in your form's cleaned_data attribute and pass that to a template to be rendered.
Two other comments. First, as I mentioned, the text in The Django Book is a bit outdated. In particular, you'll need to somehow deal with Django's CSRF protection since your view will be handling POST requests, assuming you're using Django 1.2+. A nice overview of how to do that is here. Second, when you're building your form, you'll probably want to use forms.CharField for the data you're talking about.
Good luck! This is a five-minute task in Django once you're accustomed to the framework.

On the python end of it, you can view these values by looking at request.POST["field_name"]. You can then pass these values to the template (different methods depending on which function you are using to call the template). Then the template will look something like
Your full name is {{ first_name }} {{ last_name }}
Let me know if you need more detail / examples.

Django - alternative to subclassing User?

I am using the standard User model (django.contrib.auth) which comes with Django. I have made some of my own models in a Django application and created a relationship between like this:
from django.db import models
from django.contrib.auth.models import User
class GroupMembership(models.Model):
user = models.ForeignKey(User, null = True, blank = True, related_name='memberships')
#other irrelevant fields removed from example
So I can now do this to get all of a user's current memberships:
user.memberships.all()
However, I want to be able to do a more complex query, like this:
user.memberships.all().select_related('group__name')
This works fine but I want to fetch this data in a template. It seems silly to try to put this sort of logic inside a template (and I can't seem to make it work anyway), so I want to create a better way of doing it. I could sub-class User, but that doesn't seem like a great solution - I may in future want to move my application into other Django sites, and presumably if there was any another application that sub-classed User I wouldn't be able to get it to work.
Is the best to create a method inside GroupMembership called something like get_by_user(user)? Would I be able to call this from a template?
I would appreciate any advice anybody can give on structuring this - sorry if this is a bit long/vague.

First, calling select_related and passing arguments, doesn't do anything. It's a hint that cache should be populated.
You would never call select_related in a template, only a view function. And only when you knew you needed all those related objects for other processing.
"Is the best to create a method inside GroupMembership called something like get_by_user(user)?"
You have this. I'm not sure what's wrong with it.
GroupMembership.objects.filter( user="someUser" )
"Would I be able to call this from a template?"
No. That's what view functions are for.
groups = GroupMembership.objects.filter( user="someUser" )
Then you provide the groups object to the template for rendering.
Edit
This is one line of code; it doesn't seem that onerous a burden to include this in all your view functions.
If you want this to appear on every page, you have lots of choices that do not involve repeating this line of code..
A view function can call another function.
You might want to try callable objects instead of simple functions; these can subclass a common callable object that fills in this information.
You can add a template context processor to put this into the context of all templates that are rendered.
You could write your own decorator to assure that this is done in every view function that has the decorator.

Model and Validation Confusion - Looking for advice

I'm somewhat new to Python, Django, and I'd like some advice on how to layout the code I'd like to write.
I have the model written that allows a file to be uploaded. In the models save method I'm checking if the file has a specific extension. If it has an XML extension I'm opening the file and grabbing some information from the file to save in the database. I have this model working. I've tested it in the built-in administration. It works.
Currently when there's an error (it's not an XML file; the file can't be opened; a specific attribute doesn't exist) I'm throwing an custom "Exception" error. What I would like to do is some how pass these "Exception" error messages to the view (whether that's a custom view or the built-in administration view) and have an error message displayed like if the forms library was being used. Is that possible?
I'm starting to think I'm going to have to write the validation checks again using the forms library. If that's the case, is it possible to still use the built-in administration template, but extend the form it uses to add these custom validations?
Anything to help my confusion would be appreciated.
UPDATE:
Here's my model so far, for those who are asking, "nzb" is the XML file field.
http://dpaste.com/hold/6101/
The admin interface will use the Form you associate with your model; your own views can also use the form.
This is exactly what I'd like to do. However, I don't know how to associate my forms with my models. When ever I've created forms in the past they've always acted as their own entity. I could never get the administration views to use them while using the ModelForm class. Can you shead any light on this?
I've read over the link you gave me and it seams to be what I've done in the past, with no luck.
Getting attributes from the file, should probably be a method.
Sorry, could you please elaborate on this? A method where?
UPDATE:
It seams I've been compleatly missing this step to link a form to the administration view.
http://docs.djangoproject.com/en/dev/ref/contrib/admin/#adding-custom-validation-to-the-admin
This should now allow me to do the validation in a Form. However, I'm still confused about how to actually handle the validation. S.Lott says it should be a method?

The Form errors are automatically part of the administrative view.
See http://docs.djangoproject.com/en/dev/ref/forms/validation/#ref-forms-validation
You're happiest if you validate in a Form -- that's what Forms are for. The admin interface will use the Form you associate with your model; your own views can also use the form.
Getting attributes from the file, should probably be a separate method of the model class. The separate method of the model class can be used by the save() method of the model class or invoked at other times by view functions.
"I could never get the administration views to use them while using the ModelForm class."
http://docs.djangoproject.com/en/dev/ref/contrib/admin/#form
http://docs.djangoproject.com/en/dev/ref/contrib/admin/#adding-custom-validation-to-the-admin
"I'm still confused about how to actually handle the validation. S.Lott says it should be a method?"
Validation in a form is done with a clean() method or a clean_somefield() method.
The "Adding custom validation to the admin" link (above) shows how to add the clean_name method to the "MyArticleAdminForm" form.
If you're still confused, trying actually typing the code from the Django web page and see what it does.

I guess the best way would be to implement a special field class that extends FileField with custom validation of the uploaded file.
The validation is implemented in the field's clean method. It should check the XML file and raise ValidationErrors if it encounters errors. The admin system should then treat your custom errors like any other field errors.
The ImageField class is a good example of special validation like this — I recommend just reading through the source.

You can provide a form that will be used by the admin site. You can then perform validations in the form code that will be displayed in the admin area.
See the docs on the admin site, and in particular the form attribute of ModelAdmin.

"I'm throwing an custom "Exception" error " - Where exactly are you throwing the exception ? In your model or in your view ?
I am confused with your question, so I am assuming that you should be asking 'Where should I catch input errors if any ? ' to yourself.
The Model and View as I see are like pieces in a small assembly line.
View/ Form validation is the first action which should be performed. If there is any issue with the input data through the forms. It should be prevented at the form level using form.is_valid() etc.
The models functionality should be to provide meta information about the entity itself apart from performing CRUD. Ideally it should not be bothered about the data it is getting for the CRUD operations.