A model is the single, definitive source of information about your data. It contains the essential fields and behaviors of the data you’re storing. Generally, each model maps to a single database table. The basics: Each model is a Python class that subclasses django.db.models.Model. Each attribute of the model represents a database field. With all of this, Django gives you an automatically-generated database-access API; see Making queries. Quick example This example model defines a Person, wh

Model API reference. For introductory material, see Models. Model field reference Field attribute reference Model _meta API Related objects reference Model class reference Model Meta options Model instance reference QuerySet API reference Lookup API reference Query Expressions Conditional Expressions Database Functions

A model is the single, definitive source of data about your data. It contains the essential fields and behaviors of the data you’re storing. Generally, each model maps to a single database table. Models Making queries Aggregation Search Managers Performing raw SQL queries Database transactions Multiple databases Tablespaces Database access optimization Examples of model relationship API usage

This topic guide describes Django’s support for interacting with multiple databases. Most of the rest of Django’s documentation assumes you are interacting with a single database. If you want to interact with multiple databases, you’ll need to take some additional steps. Defining your databases The first step to using more than one database with Django is to tell Django about the database servers you’ll be using. This is done using the DATABASES setting. This setting maps database aliases, whic

To define a one-to-one relationship, use OneToOneField. In this example, a Place optionally can be a Restaurant: from django.db import models class Place(models.Model): name = models.CharField(max_length=50) address = models.CharField(max_length=80) def __str__(self): # __unicode__ on Python 2 return "%s the place" % self.name class Restaurant(models.Model): place = models.OneToOneField( Place, on_delete=models.CASCADE, primary_key

This document explains how to output CSV (Comma Separated Values) dynamically using Django views. To do this, you can either use the Python CSV library or the Django template system. Using the Python CSV library Python comes with a CSV library, csv. The key to using it with Django is that the csv module’s CSV-creation capability acts on file-like objects, and Django’s HttpResponse objects are file-like objects. Here’s an example: import csv from django.http import HttpResponse def some_view(re

This document explains how to output PDF files dynamically using Django views. This is made possible by the excellent, open-source ReportLab Python PDF library. The advantage of generating PDF files dynamically is that you can create customized PDFs for different purposes – say, for different users or different pieces of content. For example, Django was used at kusports.com to generate customized, printer-friendly NCAA tournament brackets, as PDF files, for people participating in a March Madne

This document provides an overview of techniques and tools that can help get your Django code running more efficiently - faster, and using fewer system resources. Introduction Generally one’s first concern is to write code that works, whose logic functions as required to produce the expected output. Sometimes, however, this will not be enough to make the code work as efficiently as one would like. In this case, what’s needed is something - and in practice, often a collection of things - to impr

Django 1.5 is the first version of Django to support Python 3. The same code runs both on Python 2 (≥ 2.6.5) and Python 3 (≥ 3.2), thanks to the six compatibility layer. This document is primarily targeted at authors of pluggable applications who want to support both Python 2 and 3. It also describes guidelines that apply to Django’s code. Philosophy This document assumes that you are familiar with the changes between Python 2 and Python 3. If you aren’t, read Python’s official porting guide fi

class ArrayAgg(expression, **extra) [source] Returns a list of values, including nulls, concatenated into an array.