Add documentation and source

Added documentation, source and extra files.

source/orm/library/models/person.py

@@ -0,0 +1,74 @@
+from datetime import date, timedelta
+from typing import Optional
+from uuid import uuid4
+
+from django.db import models, IntegrityError
+from django.utils import timezone
+
+import library
+
+
+class PersonQuerySet(models.QuerySet):
+    """
+    Manager for people.
+
+    """
+
+    def employees(self) -> models.QuerySet:
+        """Get only employees."""
+        return self.filter(role=Person.Role.EMPLOYEE)
+
+    def clients(self) -> models.QuerySet:
+        """Get only clients."""
+        return self.filter(role=Person.Role.CLIENT)
+
+
+class Person(models.Model):
+    """
+    Base class for people, employees and clients.
+
+    """
+
+    class Role(models.IntegerChoices):
+        EMPLOYEE = 0, "employee"
+        CLIENT = 1, "client"
+
+    role = models.PositiveSmallIntegerField(default=0, choices=Role.choices, db_index=True, verbose_name="role")
+    user = models.OneToOneField("auth.User", on_delete=models.SET_NULL, null=True, blank=True, related_name="person")
+    uuid = models.UUIDField(default=uuid4, db_index=True, verbose_name="UUID")
+    first_name = models.CharField(max_length=64, blank=False, verbose_name="first name")
+    last_name = models.CharField(max_length=64, blank=False, verbose_name="last name")
+    birth_date = models.DateField(default=date(2000, 1, 1), verbose_name="birth date")
+    creation_date = models.DateTimeField(auto_now_add=True, verbose_name="creation date")
+    picture = models.ImageField(max_length=256, null=True, blank=True, upload_to="pictures", verbose_name="picture")
+    objects = PersonQuerySet.as_manager()
+
+    class Meta:
+        verbose_name = "person"
+        verbose_name_plural = "people"
+
+    def __str__(self):
+        return f"{self.get_full_name()} ({self.get_role_display()})"
+
+    def get_full_name(self):
+        return f"{self.first_name} {self.last_name}"
+
+    def borrow(self, book: "library.models.Book", duration: int = 7) -> Optional["library.models.Loan"]:
+        """
+        Borrow a book.
+
+        Args:
+            book: book instance to borrow
+            duration: expected duration of loan in days
+
+        Returns:
+            If the book can be borrowed, return the new `Loan` object.
+            If not, return `None`.
+
+        """
+        try:
+            deadline = timezone.now() + timedelta(days=duration)
+            loan = self.loans.create(person=self, book=book, expected_return=deadline)
+            return loan
+        except IntegrityError:
+            return None