View layer

Introduction

If you are using django in a fullstack way, meaning with django views and templates, you surely want to use this extra requirement.

Just install the package like this:

pip install ai-django-core[view-layer]

If you are using pipenv, you can add the following line to your Pipfile:

ai-django-core = {extras = ["view-layer"],version = "*"}

Forms

CrispyLayoutFormMixin

This neat mixin provides a basic setup to turn a regular Django form into a nice bootstrapy crispy form.

class MyForm(CrispyLayoutFormMixin, forms.Form):
    pass

The form will have the following properties:

Attribute	Default configuration
Form tag	Yes
Form class	form-horizontal form-bordered form-row-stripped
Method	POST
Submit button	Set, called “Save”
Label class	col-md-3
Field class	col-md-9
Label size	col-md-offset-3

Formsets

CountChildrenFormsetMixin

This mixin provides a method which returns the current number of children of this formset. It automatically takes care of deleted or to-be-deleted children. Have a look at the example use-case below:

class DataFieldFormset(CountChildrenFormsetMixin, BaseInlineFormSet):

    def clean(self):
        cleaned_data = super().clean()

        # Count children
        number_of_children = self.get_number_of_children()

        # do some magic

        return cleaned_data

Note that the form needs to be validated before you can use this method.

Formset Views

This package provides two mixins supporting class-based views combined with formsets. The FormsetCreateViewMixin is to be used with a generic.CreateView, the FormsetUpdateViewMixin together with generic.UpdateView.

The idea behind these mixins to make handling formset less pain and provide the comfy feeling you are used from regular forms.

Here is an example for a create view:

class MyModelCreateView(FormsetCreateViewMixin, generic.CreateView):
    model = MyModel
    template_name = 'my_app/my_model_edit.html'
    form_class = MyModelEditForm
    formset_class = inlineformset_factory(MyModel, MyModelChild,
                                          form=MyModelChildForm,
                                          formset=MyModelChildFormset)

    def get_formset_kwargs(self):
        # this is optional!
        kwargs = super().get_formset_kwargs()
        kwargs['request'] = self.request
        return kwargs

You just define - similar to the regular form - a formset_class as a class attribute. All the required handling like validation will happen magically. If you need to pass additional values to your formset, just extend the method get_formset_kwargs() as you would for djangos get_form_kwargs().

If you want to update a model and its children, here is an example for the edit-case:

class MyModelEditView(FormsetUpdateViewMixin, generic.UpdateView):
    model = MyModel
    template_name = 'my_app/my_model_edit.html'
    form_class = MyModelEditForm
    formset_class = inlineformset_factory(MyModel, MyModelChild,
                                          form=MyModelChildForm,
                                          formset=MyModelChildFormset)

    def get_formset_kwargs(self):
        # this is optional!
        kwargs = super().get_formset_kwargs()
        kwargs['request'] = self.request
        return kwargs

View mixins

CustomPermissionMixin

If you want to handle some custom permission check for which you cannot use the regular django permissions, just derive your class-based view from CustomPermissionMixin and add the method validate_permissions() with your custom logic. Notice that it has to return a boolean value.

For example, you want to allow only the “owner” of an object to view its detail page:

from django.views import generic


class MyModelDetailView(CustomPermissionMixin, generic.DetailView):
    ...

    def validate_permissions(self):
        object = super().get_object()
        if self.request.user.employee:
            return False
        return True

If the method returns False, the regular dispatch will just simply render your 403 page and skip all the other things within the view.

HtmxResponseMixin

The HtmxResponseMixin is a neat helper for passing headers to your HTMX frontend. You can set the HX-Redirect and the HX-Trigger headers as a class attribute of your view and don’t have to worry about how to fiddle it into your Django response. Misconfiguration will lead to an error.

HX-Redirect

The HTMX docs are very brief about the HX-Redirect header. If you want to make a call to your backend and in response to this reload your page, you can achieve this as follows:

from ai_django_core.view_layer.htmx_mixins import HtmxResponseMixin
from django.urls import reverse_lazy
from django.views import generic


class MyView(HtmxResponseMixin, generic.View):
    hx_redirect_url = reverse_lazy('myapp:mymodel-view')
    ...

A typical scenario would be that you delete something from your page or have multiple changes on your previous page you don’t want to update all one by one.

If you need a more elaborate way to set up your redirect url, you can overwrite the getter.

# views.py
from ai_django_core.view_layer.htmx_mixins import HtmxResponseMixin
from django.urls import reverse
from django.views import generic


class MyView(HtmxResponseMixin, generic.View):

   def get_hx_redirect_url(self):
      return reverse('myapp:mymodel-view', kwargs={...})

HX-Trigger

HX-Triggers will be converted to HTMX javascript events and can be listened to by your HTMX components in the frontend. Take care that you have to listen on from:body, otherwise your events won’t be detected. The moment, your frontend detects the event, a new call to the backend is triggered to rerender the defined component.

<a hx-get="{% url 'notification:menu-list' %}"
   hx-trigger="updateNotificationMenu from:body"
   ...>Notifications</a>

The updateNotificationMenu is the javascript event, which will be sent from the backend.

from ai_django_core.view_layer.htmx_mixins import HtmxResponseMixin
from django.views import generic


class MyView(HtmxResponseMixin, generic.View):
    hx_trigger = 'updateNotificationMenu'
    ...

This is the most straight-forward case. You send a signal without any context and listen to it with HTMX.

If you want to add context, for example you are using some kind of notification library, like toastr or UIKit, you can directly send the along with the event.

# views.py
from ai_django_core.view_layer.htmx_mixins import HtmxResponseMixin
from django.views import generic


class MyView(HtmxResponseMixin, generic.View):
    hx_trigger = {'userNotification': 'Stuff happened!'}
    ...

This is the required vanilla JS:

// base.html or any javascript file
document.body.addEventListener("userNotification", function (e) {
    UIkit.notification({
        message: e.detail.value,
        status: 'success',
        pos: 'top-center',
        timeout: 1000,
    });
});

Attention: If you want to send multiple events, you have to use the second option, even if you don’t provide any context.

# views.py
from ai_django_core.view_layer.htmx_mixins import HtmxResponseMixin
from django.views import generic


class MyView(HtmxResponseMixin, generic.View):
   hx_trigger = {'updateNotificationMenu': None, 'updateOtherComponent': None}
   ...

If you need a more elaborate way to set up your triggers, you can overwrite the getter.

# views.py
from ai_django_core.view_layer.htmx_mixins import HtmxResponseMixin
from django.views import generic


class MyView(HtmxResponseMixin, generic.View):

   def get_hx_trigger(self):
      return {'my_event': None}

RequestInFormKwargsMixin

The RequestInFormKwargsMixin is a handy helper for passing the request from the view to the form. If you need for example the current request user within the form, you need to have the current request available.

Attention: It is encouraged to only pass what you need and therefore - in most cases - pass the user object using UserInFormKwargsMixin instead of this mixin.

Just add the mixin to your class-based view:

from ai_django_core.view_layer.views import RequestInFormKwargsMixin
from django.views import generic


# views.py
class MyModelCreateView(RequestInFormKwargsMixin, generic.CreateView):
    model = MyModel
    form_class = MyModelForm
    ...


# forms.py
class MyModelForm(forms.Form):

    def __init__(self, *args, **kwargs):
        # Get request from kwargs
        self.request = kwargs.pop('request')

UserInFormKwargsMixin

The UserInFormKwargsMixin is a handy helper for passing the request user from the view to the form. A common use-case would be to set the ownership of the to-be-created object or store the last user changing this record.

Just add the mixin to your class-based view:

from ai_django_core.view_layer.views import UserInFormKwargsMixin
from django import forms
from django.views import generic


# views.py
class MyModelCreateView(UserInFormKwargsMixin, generic.CreateView):
    model = MyModel
    form_class = MyModelForm
    ...


# forms.py
class MyModelForm(forms.Form):

    def __init__(self, *args, **kwargs):
        # Get request from kwargs
        self.user = kwargs.pop('user')

Make sure that you overwrite the __init__\ ``method of your form and move the `request` to the class. Otherwise thesuper()`` will detect an unrecognised parameter within the kwargs and raise an error:

from django.forms.models import ModelForm


class MyModelForm(ModelForm):

    def __init__(self, *args, **kwargs):
        # Get request from kwargs
        self.request = kwargs.pop('request', None)

        # Call the parent method
        super().__init__(*args, **kwargs)

That’s it.

DjangoPermissionRequiredMixin

General setup

In most cases your Django views will require a login and some permissions to access it. Ensuring this manually is tedious and error-prone. Therefore, we implemented a neat mixin which ensures by default (“security by design” pattern) that the user needs to be logged in and has the defined permissions.

from ai_django_core.view_layer.mixins import DjangoPermissionRequiredMixin
from django.views import generic


class MyModelListView(DjangoPermissionRequiredMixin, generic.ListView):
    model = MyModel
    permission_list = ('account.view_my_model',)
    ...

When you extend from this mixin, you can set the class attribute permission_list which has to be a list or tuple.

Note, that you have to define the url to your login view, so the mixin can redirect your unauthenticated users correctly. It defaults to redirect('login-view').

from ai_django_core.view_layer.mixins import DjangoPermissionRequiredMixin
from django.views import generic


class MyModelListView(DjangoPermissionRequiredMixin, generic.ListView):
    model = MyModel
    permission_list = ('account.view_my_model',)

    def get_login_url(self):
        return reverse('my-login-view')

Public endpoints

If you require an open view endpoint, just set the class flag login_required to False.

from ai_django_core.view_layer.mixins import DjangoPermissionRequiredMixin
from django.views import generic


class PublicLandingPageView(DjangoPermissionRequiredMixin, generic.TemplateView):
    login_required = False
    permission_list = ()
    ...

Testing

Setup

As stated above, ensuring that every single view is protected is tedious and error-prone. Therefore, this package provides a test mixin to ensure the following things:

Your view is inheriting from the DjangoPermissionRequiredMixin mixin
You didn’t accidentally break the logic by overwriting important parts, so it ensures that the login barrier and the permission test methods are called
The permissions are set correctly

The following test case will create a bunch of default test cases covering the points 1-3.

from ai_django_core.view_layer.tests.mixins import BaseViewPermissionTestMixin
from django.test import TestCase
from my_project.my_app import views


class MyModelListViewTest(BaseViewPermissionTestMixin, TestCase):
    view_class = views.MyModelListView
    permission_list = ['account.view_my_model']

Note, that the permissions are defined redundantly. This approach reduces the risk that you make a copy/paste error when adding the permissions.

If you have implemented more custom logic, feel free to just add more test cases of your own.

Limitations

If you are using the caching decorator directly in a class-based view, the tests will fail. You have to switch to a class decorator like this:

from django.utils.decorators import method_decorator
from django.views.decorators.cache import cache_page
from django.views import generic


@method_decorator(cache_page(60 * 10), name='dispatch')
class MyModelListView(generic.ListView):
    ...

Generic views

ToggleView

Django provides a neat way of enabling the update of a given object through the generic.UpdateView. This method will validate the user data using a given form. But sometimes an update is required which doesn’t need any user data being sent, like toggling a flag or updating a timestamp. For these cases, just use the ToggleView - it works basically the same as the UpdateView - except that “POST” is required and that no form has to be defined.

from ai_django_core.view_layer.views import ToggleView


class ToggleActiveStateView(ToggleView):
    model = MyModel
    template_name = 'myapp/my_model_edit.html'

    def post(self, request, *args, **kwargs):
        # Update object
        obj = self.get_object()
        obj.is_active = not obj.is_active
        obj.save()

        return render(self.request, self.template_name, {'object': obj})