Category: Python Answers

Sometimes, we want to create a self-referential foreign key with Python Django

In this article, we’ll look at how to create a self-referential foreign key with Python Django.

How to create a self-referential foreign key with Python Django?

To create a self-referential foreign key with Python Django, we can call ForeignKey with 'self'.

For instance, we write

class CategoryModel(models.Model):
    parent = models.ForeignKey('self')

to create the parent field in CategoryModel by setting it to models.ForeignKey('self') to create a self-referencing foreign key field parent.

Conclusion

To create a self-referential foreign key with Python Django, we can call ForeignKey with 'self'.

Sometimes, we want to raise a validation error in a model’s save method in Python Django.

In this article, we’ll look at how to raise a validation error in a model’s save method in Python Django.

How to raise a validation error in a model’s save method in Python Django?

To raise a validation error in a model’s save method in Python Django, we can use is_clean to check if the model is cleaned.

For instance, we write

class BaseModelExt(models.Model):
    is_cleaned = False

    def clean(self):
        # ...
        self.is_cleaned = True

    def save(self, *args, **kwargs):
        if not self.is_cleaned:
            self.clean()

        super().save(*args, **kwargs)

to add the clean method into our model class.

After the validation checks are run in clean, we set self.is_cleaned to True.

And then in save, we call clean is is_cleaned is False.

Finally, we call save to save the values.

Conclusion

To raise a validation error in a model’s save method in Python Django, we can use is_clean to check if the model is cleaned.

Sometimes, we want to get value from form field with Python Django.

In this article, we’ll look at how to get value from form field with Python Django.

How to get value from form field with Python Django?

To get value from form field with Python Django, we can use the form’s cleaned_data property.

For instance, we write

if myform.is_valid():
  data = myform.cleaned_data
  field = data['field']

to use the myform.cleaned_data property to get the form values as a dict.

Conclusion

To get value from form field with Python Django, we can use the form’s cleaned_data property.

Sometimes, we want to get all the request headers in Python Django.

In this article, we’ll look at how to get all the request headers in Python Django.

How to get all the request headers in Python Django?

To get all the request headers in Python Django, we can use the request.headers property in our views.

request.headers is a dictionary so we can use

request.headers['User-Agent']

to get the User-Agent request header.

Conclusion

To get all the request headers in Python Django, we can use the request.headers property in our views.

Sometimes, we want to call a view function from template with Python Django.

In this article, we’ll look at how to call a view function from template with Python Django.

How to call a view function from template with Python Django?

To call a view function from template with Python Django, we can add a link to the URL of the view function.

For instance, in our template, we write

<a class="btn btn-primary" href="{% url 'delete_product'%}">Delete</a>

to add a link to the view with name delete_product in admin_page.html.

Then in urls.py, we write

path('delete_product', views.delete_product, name='delete_product')]

to add the path to the delete_product view.

Then in views.py, we write

def delete_product(request):
    if request.method == "GET":
        dest = Racket.objects.all()
        dest.delete()
        return render(request, "admin_page.html")

to add the delete_product view.

Conclusion

To call a view function from template with Python Django, we can add a link to the URL of the view function.