5.1. Database models

Now we will create the conceptual model for the relations between the different sets of data on our database

Each table represents a set of data that will be used and its properties:

Client

Client
itemstock
quantity
order

Categories

Types

Product

Itemstock

Adress

Order

OrderedItems

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With the preliminary conceptual model ready we now can create the models themselves using classes, starting with the client model:

class Client(models.Model): #? dont use plural names as django automatically puts a 's' after the name. Also a id is automatically created for each class
    name = models.CharField(max_length=200, null=True, blank=True) #? charfields are text fields. max_length determines the max number of characters
    email = models.CharField(max_length=200, null=True, blank=True)
    phone = models.CharField(max_length=200, null=True, blank=True)
    id_session = models.CharField(max_length=200, null=True, blank=True)
    user = models.OneToOneField(User, null = True, blank = True, on_delete = models.CASCADE) #? each client can only be one user and one user can only be one client. Cascade deletes everyting associated to the user if its account is deleted

Note: We added the null=True and blank=True parameters as the client will be able to perform purchases without having to create a account. The id_session attribute will be used to store the data provided by said users.

Also, the User class is already defined by Django.

You also need to import the default table for Users in django used in authentication processes:

from django.contrib.auth.models import User

Now we will repeat the procedure for the other elements, with slight variations that are shown in the code:

class Categoric(models.Model):
    name = models.CharField(max_length=200, null=True, blank=True)


class Type(models.Model):
    name = models.CharField(max_length=200, null=True, blank=True)

class Product(models.Model):
    image = models.CharField(max_length = 400, null=True, blank=True) #? we will store the file name of the image so it can be accessed in the images folder
    name = models.CharField(max_length=200, null=True, blank=True)
    price = models.DecimalField(max_digits = 7, decimal_places = 2, null=True, blank=True) #? max price is 99,999.99
    active = models.BooleanField(default=True)
    category = models.ForeignKey(Categoric, blank=True, null=True, on_delete=models.SET_NULL) #? primary key is a id associated to only that category,ForeignKey relates a category to another category with a diferent id. One product has only one category but one category has many products
    product_type = models.ForeignKey(Type, blank=True, null=True, on_delete=models.SET_NULL) #? When you delete a type or category, it will only set that product type to null, and not all the others when using CASCADE

class ItemStock(models.Model):
    product = models.ForeignKey(Product, blank=True, null=True, on_delete=models.SET_NULL) #? one itemstock is associated to a single product however one product can have many itemstocks
    color = models.CharField(max_length=200, null=True, blank=True)
    size = models.CharField(max_length=200, null=True, blank=True)
    quantity = models.IntegerField(default=0)


class Adres(models.Model):
    street = models.CharField(max_length=200, null=True, blank=True)
    number = models.IntegerField(default=0)
    apartment = models.CharField(max_length=200, null=True, blank=True)
    zip_code = models.CharField(max_length=200, null=True, blank=True)
    city = models.CharField(max_length=200, null=True, blank=True)
    state = models.CharField(max_length=200, null=True, blank=True)
    client = models.ForeignKey(Client, blank=True, null=True, on_delete=models.SET_NULL)


class Order(models.Model):
    client = models.ForeignKey(Client, blank=True, null=True, on_delete=models.SET_NULL)
    end_date = models.DateTimeField(null=True, blank=True)
    finished = models.BooleanField(default=False)
    id_transaction = models.CharField(max_length=200, null=True, blank=True)
    adress = models.ForeignKey(Adres, blank=True, null=True, on_delete=models.SET_NULL)


class OrderedItem(models.Model):
    itemstock = models.ForeignKey(ItemStock, blank=True, null=True, on_delete=models.SET_NULL)
    quantity = models.IntegerField(default=0)
    order = models.ForeignKey(Order, blank=True, null=True, on_delete=models.CASCADE)

Note: Some classes such as 'adres' are intentionally written wrong as django automatically places a s after the names of the classes.

Migrating the changes to the main database through the cmd prompt:

python manage.py makemigrations

Creating each category shown on the console.

python manage.py migrate

Applying the changes.