Tag: django-annotate

Django: Perform GROUP BY over a view queryset

django django-annotate django-filter django-queryset python

I need to perform group by over a queryset of objects already filtered by standard django filters in order to filter by how many objects in queryset are related to same foreign key object. My code now (does not work): If I filtered over all objects, I could have used but how can I do the same thing with QuerySet?

Rendering highest integer value from three models instances in django

django django-annotate django-models django-queryset python

I have three models which are related all to one model. I am rendering MyParentModel in DetailView (CBV) and passing related models as a context to render individual models ‘ranking’ field on the same template. Now I need to render same ‘ranking’ on MyParentModel ListView, but I only want to display ‘ranking’ which has highest value. Question is, how I

Django: Make a Queryset with annotate using an object’s property

django django-annotate django-views python

I have a queryset in my Django views.py. I’m using annotate to add a promo property to each object based on each object’s id. However this is not working: I get the error: name ‘id’ is not defined Answer The way you try you are trying to access a variable id. Try using the Concat function: Reference: Django database Functions

About converting custom functions in models into annotations in custom managers/querysets

django django-annotate django-queryset python

Being new to Django, I’m starting to care a bit about performance of my web application. I’m trying to transform many of my custom functions / properties which were originally in my models to querysets within custom managers. in my model I have: But I’m not clear on a few points: 1/ is there any pros or cons declaring with