Friday, July 10, 2009

Using django - database

Django seldom uses SQL. It uses python class to access DB.

Pros. You can apply one code to various types of DB.

In django database,
- Data type is equal to table.
- Class member is like a table field.

Designing data model

Create data type(table) in ur sampleapp/
from django.db import models

class SampleTable(models.Model):
  fieldA = models.IntegerField(unique=True)

Like IntegerField, there are also pre-defined field.
- TextField, DateTimefield, EmailField, URLField, FileField

Creating data type

Check if you activated your application in

Do DB sync
> ./ syncdb

You can see which SQL were generated with,
> ./ sql sampleapp

Note that it generate 'id' field automatically when it makes table.

Using DB Shell

Like we use database console to execute SQLs in terminal,
django also has shell.
> ./ shell
>>> from sampleapp.models import *
>>> record = SampleTable(fieldA=123)
>>> record.fieldA
>>> records = SampleTable.objects.all()
>>> firstRecord = SampleTable.objects.get(id=1)
>>> record.delete()

Like above, you can create a record, save it into DB, get all records or single one, access by id and delete it.

Note that until you save(), it just remain only in memory.

User data model

'User' data model is already built in.

>>> from django.contrib.auth.models import User
>>> User.objects.all()

User has many attributes like username, email and password.

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