6. Define the SQLite Database Schema

In this example, our database will have one table. The database will store the user-inputted predictions, by saving the inputted features features, the classifier prediction, an auto generated ID, and the current date/time in the database.

Here is an example of the database Predictions table:

id	predict_datetime	sepal_length	sepal_width	petal_length	petal_width	prediction
1	09-11-2020 9:00am	5.1	3.5	1.4	0.2	setosa
2	09-11-2020 9:01am	4.9	3	1.4	0.2	setosa
3	09-11-2020 9:02am	4.7	3.2	1.3	0.2	setosa
4	09-11-2020 9:03am	4.6	3.1	1.5	0.2	setosa
5	09-11-2020 9:04am	5	3.6	1.4	0.2	setosa

Update iris/models.py to create the Predictions table:

from django.db import models
from django.utils import timezone

# Create your models here.


class Predictions(models.Model):
    # The possible predictions the model can make in the 'predictions' field
    # defined by: (<database name>, <human readible name>)
    PREDICT_OPTIONS = [
        ('setosa', 'Setosa'),
        ('versicolor', 'Versicolor'),
        ('virginica', 'Virginica')
    ]

    # Prediction table fields (or columns) are defined by creating attributes
    # and assigning them to field instances such as models.CharField()
    predict_datetime = models.DateTimeField(default=timezone.now)
    sepal_length = models.DecimalField(decimal_places=2, max_digits=3)
    sepal_width = models.DecimalField(decimal_places=2, max_digits=3)
    petal_length = models.DecimalField(decimal_places=2, max_digits=3)
    petal_width = models.DecimalField(decimal_places=2, max_digits=3)
    prediction = models.CharField(choices=PREDICT_OPTIONS, max_length=10)

Notice that id was not included. This is because by default, Django gives each model an id = models.AutoField(primary_key=True) auto incrementing primary key.

Check here: https://www.webforefront.com/django/modeldatatypesandvalidation.html or here: https://docs.djangoproject.com/en/3.1/topics/db/models/ for more built-in field options.