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Posted in "django"

Serve private media with angular, DRF, CORS and token authentication

angularjs django drf rest

A long time has passed since my last post, I was fighting hard with a project learning django REST framework and angularjs, and now time has come to share some interesting knowledges.

This entry talks about serving private media from a django REST webservice, developed with django REST framework, to angularjs, in a scenario which uses a token authentication schema and CORS requests.

The problems to face

Let's see the problems we have to deal with.

  • Media with django are normally served directly by the web server, so they are out of the authentication/permission logic of the application
  • The token authentication schema needs every request to contain an header 'Authentication' part providing the token key (also when requesting files ...

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How to exclude choices of m2m raw_id_field in django admin

django programming django-admin

This procedure took a lot of effort to be understood, but now it seems quite easy.

Scenario

Imagine we need to create a recursive m2m relationship, something like a "related posts" field assigned to a Post model. It would be nice if we could exclude the current editing post from the available choices.

This is quite straightforward if we go with the default select multiple widget. In fact we only need to create a custom form class and override the queryset property of the related_posts field in the __init__ function, excluding the id of the current instance, and then assign such form class in the ModelAdmin class, see this SO question for more info.

But things become more ...

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Pretty raw_id_fields with django-salmonella and django-grappelli

django django-admin programming tips grappelli

Sometimes, when dealing with m2m relationships, we need to use the raw_id_fields property of the ModelAdmin class, in order to choose the related objects in a new page, where we can sort and filter the available items.

Without doubt the information that the widget used by django to treat such fields gives us is a bit poor. We only see the related objects's ids, it would be nicer to have the string representation of the object.

Here comes django-salmonella:

A raw_id_fields widget replacement that handles display of an object's string ...

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Add links to django admin changelist view

django django-admin programming tips

Sometimes you may need to add one or more links for each table row in your admin changelist view. There are many ways to do it, and here we'ss see a simple one. So this post is nothing more than a tip.

In my case I had to add a link opening a pdf view of the model item detail, here comes my implementation:

- app/models.py

from django.db import models
from django.core.urlresolvers import reverse
from django.utils.html import mark_safe

class MyModel(models.Model):
    title = models.CharField('title', max_length=255)
    # ...

    def pdf_link(self):
        return mark_safe('<a class="grp-button" href="%s" target="blank">view pdf</a>' % reverse('archiviocr-opera-pdf', args=[self.id]))
    pdf_link.short_description = _('PDF')

- app/admin ...

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Paginating the results of a Django form POST request

django forms pagination

This is quite a common situation, we have a search form which leads to a result page. The number of found results can be big enough to require pagination. If we use the classic pagination code, the posted parameters will be lost when changing page and our search gets broken.

There are several ways to solve the problem, as tux21b wrote in this stack overflow answer.

Here I will talk about the first method, using session.
In the same stack overflow page you can see an answer by rvnovaes, which surely works but in my opinion has some eliminable drawbacks. The first is that if there are many search fields the code we have to write is too long (yes ...

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How to implement modal popup django forms with bootstrap

django forms bootstrap

UPDATE 11/18/2015

I wrote another article like this, but newer, just tested and with support for both bootstrap 3 and 4-alpha, check it out:

http://www.abidibo.net/blog/2015/11/18/modal-django-forms-bootstrap-4/


Sometimes could be a good idea to have the user provide all the needed information without living the "index" or "main" page of our web application. In other terms, sometimes could be a good idea to have some forms appear on a layer, a modal ...

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Check if user belongs to a group in django templates

django tips

Generally when implementing some "authentication logic" inside a django template it's enough to check if a user has some permissions, and in such cases you can use the variable perms, which is available if (from django site):

Technically, these variables are only made available in the template context if you use RequestContext and your "django.contrib.auth.context_processors.auth", which is default. For more, see the RequestContext docs.

But could happen that you need to check if a user belongs ...

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Django chained selects with mootools

django forms mootools tips

Notice!

A due specification here!
Such method works, but IMHO should not be used with a large amount of data, since it uses a js mapping array, but is simple and requires a few lines of code, so why not to use it when we have a controlled set of data?

Introduction

This is just yet another method to implement chained (cascading) selects in django forms. I'm focusing here on the frontend form construction, not the admin area. If you're interested in the admin area instead, please take a look here.

Scenario

Imagine we have such models:

class ...

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Required class attribute in django ModelForm

django tips

Days ago' I was developing a front-end form in order to give users the opportunity to subscribe to a newsletter. I used the django ModelForm class because I didn't need nothing special except from hiding some model fields.

But I run into a problem, the compulsory fileds where handled properly in the sense that the form submission returned an error if such fields weren't filled, but there wasn't any attribute assigned to the label element in order to style it different from non-compulsory fields.

Nothing special here, nor complicated, but it costs me a while to find the reason for this, so I'll share it with you. The simple solution is to add a line ( required_css_class ...

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Convert select multiple widget to checkboxes in django admin form

django django-admin django-mptt jquery

I think this should be a nice post talking about the substitution of the default multiple select widget used in django admin interface to deal with m2m fields, with a multiple checkbox widget.

Yes I know, you may solve it this way, but I don't like such solution very much, and I think it is just not perfect for some reasons:

  • At the time of this writing the add related functionality (+) seems to be broken, throws an error, at least for me
  • It just can't be used with the django-mptt application, which is awesome to deal with data which have a tree like structure

So to graphically explain what we want to do here, say we want this ...

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