How to access PostgreSQL database in Django application

Question

I have created a simple Django application which tries to access table named fruits present in PostgreSQL database and display its contents. I followed the official Django documentation and implemented below code as far as I understand. But below procedure is incomplete I believe as fruits.objects.all() is failing to fetch any data. I am missing something can anybody point it out any help would be appreciated.

Table: fruits

models.py

from django.db import models

class fruits(models.Model):
    ID = models.CharField(max_length=20)
    Name = models.CharField(max_length=20)

    def __str__(self):
        return self.Name

views.py

from database.models import fruits

def index(request):
    data = fruits.objects.all()

    print(len(data))

    for item in data:
        print(item)

settings.py

DATABASES = {
    'default': {
        'ENGINE': 'django.db.backends.postgresql_psycopg2',
        'NAME': '<database_name>',
        'USER': '<user_name>',
        'PASSWORD': '<password>',
        'HOST': '<host_name>',
        'PORT': '',
    }
}

Class names are by convention writen with capital letter and are singular nouns. Thus class fruits should become class Fruit. Class attributes are by convention written in snake_case, thus id instead of ID, name instead of Name. Check PEP 8 and follow coding convetions. — cezar
– cezar, Commented Feb 24, 2018 at 13:24

neverwalkaloner · Accepted Answer · 2018-02-24 13:30:56Z

1

By default Django will create new table appname_modelname for model. So in your case this queryset fruits.objects.all() fetch data from app_fruits table, not fruits. You can specify table name using db_table meta option. For example to link model fruits with existing table fruits add following Meta to the model:

class fruits(models.Model):
    ID = models.IntegerField(max_length=20)
    Name = models.CharField(max_length=20)

    class Meta:
        db_table = 'fruits'

    def __str__(self):
        return self.Name

UPD

Django expect id field to be primary key by default not ID, to change this add primary_key option to ID field:

ID = models.IntegerField(max_length=20, primary_key=True)

edited Feb 24, 2018 at 13:30

answered Feb 24, 2018 at 12:32

neverwalkaloner

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5 Comments

Olivia Brown Over a year ago

I am getting this error now django.db.utils.ProgrammingError: column fruits.id does not exist LINE 1: SELECT "fruits"."id", "fruits"."Name" FROM "fruits"

neverwalkaloner Over a year ago

@OliviaBrown add primary_key=True to ID field: ID = models.CharField(max_length=20, primary_key=True).

cezar Over a year ago

I would strongly suggest against using CharField as primary key. It's a bad practice. Use rather surrogate keys.

neverwalkaloner Over a year ago

@cezar thanks I missed this part. In DB primary key is integer field. So it should be integer instead of char field in model also.

user12315602 Over a year ago

how can I access a table that wasn't made using model.Models, let's say I used the command line to make a table, and add items to that table. how can I access those items?

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